diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000..cd8eb86
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,15 @@
+; This file is for unifying the coding style for different editors and IDEs.
+; More information at http://editorconfig.org
+
+root = true
+
+[*]
+charset = utf-8
+indent_size = 4
+indent_style = space
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.md]
+trim_trailing_whitespace = false
diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..3286141
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,11 @@
+# Path-based git attributes
+# https://www.kernel.org/pub/software/scm/git/docs/gitattributes.html
+
+# Ignore all test and documentation with "export-ignore".
+/.gitattributes     export-ignore
+/.gitignore         export-ignore
+/.travis.yml        export-ignore
+/phpunit.xml.dist   export-ignore
+/.scrutinizer.yml   export-ignore
+/tests              export-ignore
+/docs               export-ignore
\ No newline at end of file
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..a16e58b
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+build
+composer.lock
+vendor
+.idea
diff --git a/.scrutinizer.yml b/.scrutinizer.yml
new file mode 100644
index 0000000..e2ef079
--- /dev/null
+++ b/.scrutinizer.yml
@@ -0,0 +1,23 @@
+filter:
+    excluded_paths: [tests/*]
+
+checks:
+    php:
+        remove_extra_empty_lines: true
+        remove_php_closing_tag: true
+        remove_trailing_whitespace: true
+        fix_use_statements:
+            remove_unused: true
+            preserve_multiple: false
+            preserve_blanklines: true
+            order_alphabetically: true
+        fix_php_opening_tag: true
+        fix_linefeed: true
+        fix_line_ending: true
+        fix_identation_4spaces: true
+        fix_doc_comments: true
+
+tools:
+    external_code_coverage:
+        timeout: 600
+        runs: 1
diff --git a/.styleci.yml b/.styleci.yml
new file mode 100644
index 0000000..247a09c
--- /dev/null
+++ b/.styleci.yml
@@ -0,0 +1 @@
+preset: psr2
diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..50f9347
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,30 @@
+dist: trusty
+language: php
+
+php:
+  - 7.0
+  - 7.1
+  - 7.2
+
+# This triggers builds to run on the new TravisCI infrastructure.
+# See: http://docs.travis-ci.com/user/workers/container-based-infrastructure/
+sudo: false
+
+## Cache composer
+cache:
+  directories:
+    - $HOME/.composer/cache
+
+before_script:
+  - travis_retry composer update ${COMPOSER_FLAGS} --no-interaction --prefer-dist
+
+script:
+  - vendor/bin/phpcs --standard=psr2 src/
+  - vendor/bin/phpunit --coverage-text --coverage-clover=coverage.clover
+
+after_script:
+  - |
+    if [[ "$TRAVIS_PHP_VERSION" == '7.0' ]]; then
+      wget https://scrutinizer-ci.com/ocular.phar
+      php ocular.phar code-coverage:upload --format=php-clover coverage.clover
+    fi
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..5a39789
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,39 @@
+# Changelog
+
+All notable changes to `php-sip2` will be documented in this file.
+
+Updates should follow the [Keep a CHANGELOG](http://keepachangelog.com/) principles.
+
+## 2.0.1 - 2018-08-01
+
+### Added
+- SIP2Client::connect now accepts a timeout parameter, default 15 seconds
+
+
+## 2.0.0 - 2018-07-29
+
+### Added
+- MIT License adopted - prior releases were GPL
+- PSR-2 formatting/naming conventions, including change of classname from sip2 to SIP2Client
+- PSR-3 logger support
+- Classes for each request and response type
+- Support for binding to particular interface
+- Full unit tests
+
+### Deprecated
+- Nothing
+
+### Fixed
+- Ensure client properly handles retries in event of CRC failure
+
+### Removed
+- original v1 classname changed
+- original public methods and variables all removed - see [MIGRATION](MIGRATION.md)
+
+### Security
+- Nothing
+
+
+## 1.0.0 - 2015-11-03
+
+- First release, GPL licensed
\ No newline at end of file
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..a5a547c
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,32 @@
+# Contributing
+
+Contributions are **welcome** and will be fully **credited**.
+
+We accept contributions via Pull Requests on [Github](https://github.com/cap60552/php-sip2).
+
+
+## Pull Requests
+
+- **[PSR-2 Coding Standard](https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-2-coding-style-guide.md)** - Check the code style with ``$ composer check-style`` and fix it with ``$ composer fix-style``.
+
+- **Add tests!** - Your patch won't be accepted if it doesn't have tests.
+
+- **Document any change in behaviour** - Make sure the `README.md` and any other relevant documentation are kept up-to-date.
+
+- **Consider our release cycle** - We try to follow [SemVer v2.0.0](http://semver.org/). Randomly breaking public APIs is not an option.
+
+- **Create feature branches** - Don't ask us to pull from your master branch.
+
+- **One pull request per feature** - If you want to do more than one thing, send multiple pull requests.
+
+- **Send coherent history** - Make sure each individual commit in your pull request is meaningful. If you had to make multiple intermediate commits while developing, please [squash them](http://www.git-scm.com/book/en/v2/Git-Tools-Rewriting-History#Changing-Multiple-Commit-Messages) before submitting.
+
+
+## Running Tests
+
+``` bash
+$ composer test
+```
+
+
+**Happy coding**!
diff --git a/ISSUE_TEMPLATE.md b/ISSUE_TEMPLATE.md
new file mode 100644
index 0000000..5b48c57
--- /dev/null
+++ b/ISSUE_TEMPLATE.md
@@ -0,0 +1,27 @@
+<!-- Provide a general summary of the issue in the Title above -->
+
+## Detailed description
+
+Provide a detailed description of the change or addition you are proposing.
+
+Make it clear if the issue is a bug, an enhancement or just a question.
+
+## Context
+
+Why is this change important to you? How would you use it?
+
+How can it benefit other users?
+
+## Possible implementation
+
+Not obligatory, but suggest an idea for implementing addition or change.
+
+## Your environment
+
+Include as many relevant details about the environment you experienced the bug in and how to reproduce it.
+
+* Version used (e.g. PHP 5.6, HHVM 3):
+* Operating system and version (e.g. Ubuntu 16.04, Windows 7):
+* Link to your project:
+* ...
+* ...
diff --git a/LICENSE.md b/LICENSE.md
new file mode 100644
index 0000000..980d5a5
--- /dev/null
+++ b/LICENSE.md
@@ -0,0 +1,22 @@
+# The MIT License (MIT)
+
+Copyright (c) 2015 John Wohlers <john@wohlershome.net>
+Copyright (c) 2018 Paul Dixon <paul@elphin.com>
+            
+> Permission is hereby granted, free of charge, to any person obtaining a copy
+> of this software and associated documentation files (the "Software"), to deal
+> in the Software without restriction, including without limitation the rights
+> to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+> copies of the Software, and to permit persons to whom the Software is
+> furnished to do so, subject to the following conditions:
+>
+> The above copyright notice and this permission notice shall be included in
+> all copies or substantial portions of the Software.
+>
+> THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+> IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+> FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+> AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+> LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+> OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+> THE SOFTWARE.
diff --git a/MIGRATION.md b/MIGRATION.md
new file mode 100644
index 0000000..2041cc0
--- /dev/null
+++ b/MIGRATION.md
@@ -0,0 +1,57 @@
+# Migration from v1.0
+
+While this is derived from [cap60552/php-sip2](https://github.com/cap60552/php-sip2) 
+many changes were made to make the code more easily testable and less complex. As a result,
+this isn't a drop-in replacement. Here's the main differences for a typical scenaio:
+
+## Before
+```php
+// create object
+$mysip = new sip2;
+
+// Set host name
+$mysip->hostname = 'server.example.com';
+$mysip->port = 6002;
+
+// Identify a patron
+$mysip->patron = '101010101';
+$mysip->patronpwd = '010101';
+
+// connect to SIP server 
+$result = $mysip->connect();
+
+// Get Charged Items Raw response
+$in = $mysip->msgPatronInformation('charged');
+
+// parse the raw response into an array
+$result = $mysip->parsePatronInfoResponse( $mysip->get_message($in) );
+
+// extra data from result
+$status = $result['fixed']['PatronStatus'];
+$name = $result['variable']['AE'];
+```
+
+## After
+```php
+use cap60552\SIP2\SIP2Client;
+use cap60552\SIP2\Request\PatronInformationRequest;
+
+// instantiate client, set any defaults used for all requests
+$mysip = new SIP2Client;
+$mysip->setDefault('PatronIdentifier', '101010101');
+$mysip->setDefault('PatronPassword', '010101');
+
+// connect to SIP server 
+$mysip->connect("server.example.com:6002");
+
+// Get Charged Items Raw response
+$request=new PatronInformationRequest();
+$request->setType('charged');
+
+$response = $mysip->sendRequest($request);
+
+// extra data from result
+$status = $response->getPatronStatus();
+$name = $response->getPersonalName();
+
+```
\ No newline at end of file
diff --git a/PULL_REQUEST_TEMPLATE.md b/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 0000000..86246b3
--- /dev/null
+++ b/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,43 @@
+<!--- Provide a general summary of your changes in the Title above -->
+
+## Description
+
+Describe your changes in detail.
+
+## Motivation and context
+
+Why is this change required? What problem does it solve?
+
+If it fixes an open issue, please link to the issue here (if you write `fixes #num`
+or `closes #num`, the issue will be automatically closed when the pull is accepted.)
+
+## How has this been tested?
+
+Please describe in detail how you tested your changes.
+
+Include details of your testing environment, and the tests you ran to
+see how your change affects other areas of the code, etc.
+
+## Screenshots (if appropriate)
+
+## Types of changes
+
+What types of changes does your code introduce? Put an `x` in all the boxes that apply:
+- [ ] Bug fix (non-breaking change which fixes an issue)
+- [ ] New feature (non-breaking change which adds functionality)
+- [ ] Breaking change (fix or feature that would cause existing functionality to change)
+
+## Checklist:
+
+Go over all the following points, and put an `x` in all the boxes that apply.
+
+Please, please, please, don't send your pull request until all of the boxes are ticked. Once your pull request is created, it will trigger a build on our [continuous integration](http://www.phptherightway.com/#continuous-integration) server to make sure your [tests and code style pass](https://help.github.com/articles/about-required-status-checks/).
+
+- [ ] I have read the **[CONTRIBUTING](CONTRIBUTING.md)** document.
+- [ ] My pull request addresses exactly one patch/feature.
+- [ ] I have created a branch for this patch/feature.
+- [ ] Each individual commit in the pull request is meaningful.
+- [ ] I have added tests to cover my changes.
+- [ ] If my change requires a change to the documentation, I have updated it accordingly.
+
+If you're unsure about any of these, don't hesitate to ask. We're here to help!
diff --git a/README.md b/README.md
index 8f63e93..a259146 100644
--- a/README.md
+++ b/README.md
@@ -1,40 +1,168 @@
-# SIP2 communication library for PHP
+# php-sip2
 
-PHP class library to facilitate communication with Integrated Library System (ILS) servers via 3M's SIP2.
+[![Latest Version on Packagist][ico-version]][link-packagist]
+[![Software License][ico-license]](LICENSE.md)
+[![Build Status][ico-travis]][link-travis]
+[![Coverage Status][ico-scrutinizer]][link-scrutinizer]
+[![Quality Score][ico-code-quality]][link-code-quality]
+[![Total Downloads][ico-downloads]][link-downloads]
 
 
-## Composer Installation
+PHP client library to facilitate communication with Integrated Library System (ILS) servers via 3M's SIP2.
+
+This is derived from [cap60552/php-sip2](https://github.com/cap60552/php-sip2) by John Wohlers, 
+with following improvements:
+
+* MIT license (with consent of original author who used GPL)
+* Separate classes for each SIP2 request and response type
+* Ability to bind to specific interface when making requests
+* Full unit tests
+* PSR-2 formatting conventions
+* PSR-3 logging
+* PSR-4 auto-loading
+
+## Install
+
+Via Composer
+
+``` bash
+$ composer require cap60552/php-sip2
+```
+
+## Example
+
+Here's a typical example of use 
+```php
+use cap60552\SIP2\SIP2Client;
+use cap60552\SIP2\Request\PatronInformationRequest;
+
+// instantiate client, set any defaults used for all requests,
+// typically you might set the PatronIdentifier and PatronPassword
+// so that you don't have to set this for every request
+$mysip = new SIP2Client;
+$mysip->setDefault('PatronIdentifier', '101010101');
+$mysip->setDefault('PatronPassword', '010101');
+
+// connect to SIP server 
+$mysip->connect("server.example.com:6002");
+
+// to make a request, instantiate relevant request class
+// and configure as appropriate
+$request=new PatronInformationRequest();
+$request->setType('charged');
+
+// send the request, obtaining, in this case a
+// PatronInformationResponse object
+$response = $mysip->sendRequest($request);
+
+// now we can obtain information from the result object
+$status = $response->getPatronStatus();
+$name = $response->getPersonalName();
 
-To install this package, run this command:
-```sh
-composer require cap60552/php-sip2
 ```
 
-## General Installation
-Copy the sip2.class.php file to a location in your php_include path.
-
-## General Usage
-
-	// create object
-	$mysip = new sip2;
-
-	// Set host name
-	$mysip->hostname = 'server.example.com';
-	$mysip->port = 6002;
- 
-	// Identify a patron
-	$mysip->patron = '101010101';
-	$mysip->patronpwd = '010101';
- 
-	// connect to SIP server 
-	$result = $mysip->connect();
-
-	// Get Charged Items Raw response
-	$in = $mysip->msgPatronInformation('charged');
-	
-	// parse the raw response into an array
-	$result = $mysip->parsePatronInfoResponse( $mysip->get_message($in) );
-	
-## Contribution
-
-Feel free to contribute!
\ No newline at end of file
+## SIP2 requests and responses
+
+All requests defined in SIP2 are available - note that not all SIP2
+services will support every request.
+
+
+| Request  | Response |
+| ------------- | ------------- |
+| PatronStatusRequest  | PatronStatusResponse  |
+| CheckOutRequest | CheckOutResponse |
+| CheckInRequest | CheckInResponse |
+| BlockPatronRequest | PatronStatusResponse |
+| SCStatusRequest | ASCStatusResponse |
+| RequestACSResendRequest | _previous response_ |
+| LoginRequest | LoginResponse |
+| PatronInformationRequest | PatronInformationResponse |
+| EndPatronSessionRequest | EndSessionResponse |
+| FeePaidRequest | FeePaidResponse |
+| ItemInformationRequest | ItemInformationResponse |
+| ItemStatusUpdateRequest | ItemStatusUpdateResponse |
+| PatronEnableRequest | PatronEnableResponse |
+| HoldRequest | HoldResponse |
+| RenewRequest | RenewResponse |
+| RenewAllRequest | RenewAllResponse |
+
+
+## Migration from v1.0
+
+See [MIGRATION](MIGRATION.md) for details.
+
+## Binding to a specific local outbound address
+
+If connecting to a SIP2 service over the internet, such services will usually be tightly firewalled
+to specific IPs. If your client software is running on a machine with multiple outbound interfaces,
+you may wish to pick the specific interface so that the SIP2 server sees the correct IP.
+
+To do this, specify the IP with `bindTo` public member variable *before* calling `connect()`:
+
+
+``` php
+use cap60552\SIP2\SIP2Client;
+
+
+// create object
+$mysip = new SIP2Client;
+
+// Set host name
+$mysip->hostname = 'server.example.com';
+$mysip->port = 6002;
+
+//ensure outbound connections go from this IP address
+$mysip->bindTo = '1.2.3.4';
+
+// connect to SIP server 
+$result = $mysip->connect();
+```
+
+
+## Change log
+
+Please see [CHANGELOG](CHANGELOG.md) for more information on what has changed recently.
+
+## Testing
+
+``` bash
+$ composer test
+```
+
+## Contributing
+
+Please see [CONTRIBUTING](CONTRIBUTING.md) for details.
+
+## Security
+
+If you discover any security related issues, please email paul@elphin.com instead of using the 
+issue tracker.
+
+## Credits
+
+- [John Wohlers][link-author1]
+- [Paul Dixon][link-author2]
+- [All Contributors][link-contributors]
+
+## License
+
+The MIT License (MIT). Please see [License File](LICENSE.md) for more information.
+
+Note that prior to v2.0.0, the GPL licence was used. The original author, John Wohlers, kindly
+agreed to allow the MIT license terms.
+
+[ico-version]: https://img.shields.io/packagist/v/cap60552/php-sip2.svg?style=flat-square
+[ico-license]: https://img.shields.io/badge/license-MIT-brightgreen.svg?style=flat-square
+[ico-travis]: https://img.shields.io/travis/cap60552/php-sip2/master.svg?style=flat-square
+[ico-scrutinizer]: https://img.shields.io/scrutinizer/coverage/g/cap60552/php-sip2.svg?style=flat-square
+[ico-code-quality]: https://img.shields.io/scrutinizer/g/cap60552/php-sip2.svg?style=flat-square
+[ico-downloads]: https://img.shields.io/packagist/dt/cap60552/php-sip2.svg?style=flat-square
+
+[link-packagist]: https://packagist.org/packages/cap60552/php-sip2
+[link-travis]: https://travis-ci.org/cap60552/php-sip2
+[link-scrutinizer]: https://scrutinizer-ci.com/g/cap60552/php-sip2/code-structure
+[link-code-quality]: https://scrutinizer-ci.com/g/cap60552/php-sip2
+[link-downloads]: https://packagist.org/packages/cap60552/php-sip2
+[link-author1]: https://github.com/cap60552
+[link-author2]: https://github.com/cap60552
+[link-contributors]: ../../contributors
diff --git a/composer.json b/composer.json
index 00f77be..1990297 100644
--- a/composer.json
+++ b/composer.json
@@ -1,23 +1,62 @@
 {
     "name": "cap60552/php-sip2",
-    "description": "PHP class library to facilitate communication with Integrated Library System (ILS) servers via 3M's SIP2.",
-	"type": "library",
+    "type": "library",
+    "description": "Communicate with Integrated Library System (ILS) servers via 3M's SIP2",
+    "keywords": [
+        "SIP2",
+        "SIP2Client",
+        "ILS",
+        "php-sip2"
+    ],
+    "homepage": "https://github.com/cap60552/php-sip2",
+    "license": "MIT",
     "authors": [
         {
             "name": "John Wohlers",
             "email": "john@wohlershome.net",
-            "role": "Maintainer"
+            "homepage": "https://github.com/cap60552",
+            "role": "Developer"
+        },
+        {
+            "name": "Paul Dixon",
+            "email": "paul@elphin.com",
+            "homepage": "https://github.com/cap60552",
+            "role": "Developer"
         }
     ],
-    "homepage": "https://github.com/cap60552/php-sip2",
-    "license": "GPL-3.0",
-    "support": {
-        "issues": "https://github.com/cap60552/php-sip2/issues",
-		"source": "https://github.com/cap60552/php-sip2",
-		"docs": "https://github.com/cap60552/php-sip2/tree/master/doc"
+    "require": {
+        "php": "~7.0",
+        "clue/socket-raw": "^1.3",
+        "psr/log": "^1.0"
+    },
+    "require-dev": {
+        "phpunit/phpunit" : ">=5.4.3",
+        "squizlabs/php_codesniffer": "^2.3"
+    },
+    "suggest": {
+        "psr/log-implementation": "A PSR-3 compatible logger is recommended for troubleshooting"
     },
     "autoload": {
-        "classmap": ["/"]
+        "psr-4": {
+            "cap60552\\SIP2\\": "src"
+        }
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "cap60552\\SIP2\\": "tests"
+        }
+    },
+    "scripts": {
+        "test": "phpunit",
+        "check-style": "phpcs -p --standard=PSR2 --runtime-set ignore_errors_on_exit 1 --runtime-set ignore_warnings_on_exit 1 src tests",
+        "fix-style": "phpcbf -p --standard=PSR2 --runtime-set ignore_errors_on_exit 1 --runtime-set ignore_warnings_on_exit 1 src tests"
+    },
+    "extra": {
+        "branch-alias": {
+            "dev-master": "1.0-dev"
+        }
+    },
+    "config": {
+        "sort-packages": true
     }
 }
-
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
new file mode 100644
index 0000000..4f294dd
--- /dev/null
+++ b/phpunit.xml.dist
@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit bootstrap="vendor/autoload.php"
+         backupGlobals="false"
+         backupStaticAttributes="false"
+         colors="true"
+         verbose="true"
+         convertErrorsToExceptions="true"
+         convertNoticesToExceptions="true"
+         convertWarningsToExceptions="true"
+         processIsolation="false"
+         stopOnFailure="false">
+    <testsuites>
+        <testsuite name="SIP2Client Test Suite">
+            <directory>tests</directory>
+        </testsuite>
+    </testsuites>
+    <filter>
+        <whitelist>
+            <directory suffix=".php">src/</directory>
+        </whitelist>
+    </filter>
+    <logging>
+        <log type="tap" target="build/report.tap"/>
+        <log type="junit" target="build/report.junit.xml"/>
+        <log type="coverage-html" target="build/coverage" lowUpperBound="35" highLowerBound="70"/>
+        <log type="coverage-text" target="build/coverage.txt"/>
+        <log type="coverage-clover" target="build/logs/clover.xml"/>
+    </logging>
+</phpunit>
diff --git a/sip2.class.php b/sip2.class.php
deleted file mode 100644
index 5a37d1f..0000000
--- a/sip2.class.php
+++ /dev/null
@@ -1,858 +0,0 @@
-<?php
-/**
-* SIP2 Class
-*
-* This class provides a method of communicating with an Integrated
-* Library System using 3M's SIP2 standard. 
-*
-* PHP version 5
-*
-*
-* @package    
-* @author     John Wohlers <john@wohlershome.net>
-* @licence    http://opensource.org/licenses/gpl-3.0.html
-* @copyright  John Wohlers <john@wohlershome.net>
-* @version    1.0.1
-* @link       https://github.com/cap60552/php-sip2/
-*/
-
-/**
-*  
-*  TODO
-*   - Clean up variable names, check for consistency
-*   - Add better i18n support, including functions to handle the SIP2 language definitions
-*
-*/
-
-
-class sip2 
-{
-
-    /* Public variables for configuration */
-    public $hostname;
-    public $port         = 6002; /* default sip2 port for Sirsi */
-    public $library      = ''; 
-    public $language     = '001'; /* 001= english */
-
-    /* Patron ID */
-    public $patron       = ''; /* AA */
-    public $patronpwd    = ''; /* AD */
-    
-    /* Terminal password */
-    public $AC           = ''; /*AC */
-    
-    /* Maximum number of resends allowed before get_message gives up */
-    public $maxretry     = 3;
-    
-    /* Terminators 
-    *
-    * From page 15 of SPI2 v2 docs:
-    * All messages must end in a carriage return (hexadecimal 0d).
-    * 
-    * Technically $msgTerminator should be set to \r only. However some vendors mistakenly require the \r\n.  
-    *
-    * TODO: Create a function to set this, rather than exposing the variable as public.   
-    */
-    public $msgTerminator = "\r\n";
-
-    public $fldTerminator = '|';
-    
-    /* Login Variables */
-    public $UIDalgorithm = 0;   /* 0    = unencrypted, default */
-    public $PWDalgorithm = 0;   /* undefined in documentation */
-    public $scLocation   = '';  /* Location Code */
-
-    /* Debug */
-    public $debug        = false;
-    
-    /* Public variables used for building messages */
-    public $AO = 'WohlersSIP';
-    public $AN = 'SIPCHK';
-    
-    /* Private variable to hold socket connection */
-    private $socket;
-    
-    /* Sequence number counter */
-    private $seq   = -1;
-
-    /* resend counter */
-    private $retry = 0;
-    
-    /* Work area for building a message */
-    private $msgBuild = '';
-    private $noFixed = false;
-    
-    function msgPatronStatusRequest() 
-    {
-        /* Server Response: Patron Status Response message. */
-        $this->_newMessage('23');
-        $this->_addFixedOption($this->language, 3);
-        $this->_addFixedOption($this->_datestamp(), 18);
-        $this->_addVarOption('AO',$this->AO);
-        $this->_addVarOption('AA',$this->patron);
-        $this->_addVarOption('AC',$this->AC);
-        $this->_addVarOption('AD',$this->patronpwd);
-        return $this->_returnMessage();     
-    }
-    
-    function msgCheckout($item, $nbDateDue ='', $scRenewal='N', $itmProp ='', $fee='N', $noBlock='N', $cancel='N') 
-    {
-        /* Checkout an item  (11) - untested */
-        $this->_newMessage('11');
-        $this->_addFixedOption($scRenewal, 1);
-        $this->_addFixedOption($noBlock, 1);
-        $this->_addFixedOption($this->_datestamp(), 18);
-        if ($nbDateDue != '') {
-            /* override default date due */
-            $this->_addFixedOption($this->_datestamp($nbDateDue), 18);
-        } else {
-            /* send a blank date due to allow ACS to use default date due computed for item */
-            $this->_addFixedOption('', 18);
-        }
-        $this->_addVarOption('AO',$this->AO);
-        $this->_addVarOption('AA',$this->patron);
-        $this->_addVarOption('AB',$item);
-        $this->_addVarOption('AC',$this->AC);
-        $this->_addVarOption('CH',$itmProp, true);
-        $this->_addVarOption('AD',$this->patronpwd, true);
-        $this->_addVarOption('BO',$fee, true); /* Y or N */
-        $this->_addVarOption('BI',$cancel, true); /* Y or N */
-        
-        return $this->_returnMessage();
-    }
-    
-    function msgCheckin($item, $itmReturnDate, $itmLocation = '', $itmProp = '', $noBlock='N', $cancel = '') 
-    {
-        /* Check-in an item (09) - untested */
-        if ($itmLocation == '') {
-            /* If no location is specified, assume the default location of the SC, behaviour suggested by spec*/
-            $itmLocation = $this->scLocation;
-        } 
-
-        $this->_newMessage('09');
-        $this->_addFixedOption($noBlock, 1);
-        $this->_addFixedOption($this->_datestamp(), 18);
-        $this->_addFixedOption($this->_datestamp($itmReturnDate), 18);
-        $this->_addVarOption('AP',$itmLocation);
-        $this->_addVarOption('AO',$this->AO);
-        $this->_addVarOption('AB',$item);
-        $this->_addVarOption('AC',$this->AC);
-        $this->_addVarOption('CH',$itmProp, true);
-        $this->_addVarOption('BI',$cancel, true); /* Y or N */
-        
-        return $this->_returnMessage();
-    }
-
-    function msgBlockPatron($message, $retained='N') 
-    {
-        /* Blocks a patron, and responds with a patron status response  (01) - untested */
-        $this->_newMessage('01');
-        $this->_addFixedOption($retained, 1); /* Y if card has been retained */
-        $this->_addFixedOption($this->_datestamp(), 18);
-        $this->_addVarOption('AO',$this->AO);
-        $this->_addVarOption('AL',$message);
-        $this->_addVarOption('AA',$this->AA);
-        $this->_addVarOption('AC',$this->AC);
-        
-        return $this->_returnMessage();
-    }
-    
-    function msgSCStatus($status = 0, $width = 80, $version = 2) 
-    {
-        /* selfcheck status message, this should be sent immediately after login  - untested */
-        /* status codes, from the spec:
-            * 0 SC unit is OK
-            * 1 SC printer is out of paper
-            * 2 SC is about to shut down
-            */
-
-        if ($version > 3) {
-            $version = 2;
-        }
-        if ($status < 0 || $status > 2) {
-            $this->_debugmsg( "SIP2: Invalid status passed to msgSCStatus" );
-            return false;
-        }    
-        $this->_newMessage('99');
-        $this->_addFixedOption($status, 1);
-        $this->_addFixedOption($width, 3);
-        $this->_addFixedOption(sprintf("%03.2f",$version), 4);
-        return $this->_returnMessage();
-    }
-
-    function msgRequestACSResend () 
-    {
-        /* Used to request a resend due to CRC mismatch - No sequence number is used */
-        $this->_newMessage('97');
-        return $this->_returnMessage(false);
-    }
-
-    function msgLogin($sipLogin, $sipPassword) 
-    {
-        /* Login (93) - untested */
-        $this->_newMessage('93');
-        $this->_addFixedOption($this->UIDalgorithm, 1);
-        $this->_addFixedOption($this->PWDalgorithm, 1);
-        $this->_addVarOption('CN',$sipLogin);
-        $this->_addVarOption('CO',$sipPassword);
-        $this->_addVarOption('CP',$this->scLocation, true);
-        return $this->_returnMessage();
-
-    }
-
-    function msgPatronInformation($type, $start = '1', $end = '5') 
-    {
-
-        /* 
-        * According to the specification:
-        * Only one category of items should be  requested at a time, i.e. it would take 6 of these messages, 
-        * each with a different position set to Y, to get all the detailed information about a patron's items.
-        */
-        $summary['none']     = '      ';
-        $summary['hold']     = 'Y     ';
-        $summary['overdue']  = ' Y    ';
-        $summary['charged']  = '  Y   ';
-        $summary['fine']     = '   Y  ';
-        $summary['recall']   = '    Y ';
-        $summary['unavail']  = '     Y';
-        
-        /* Request patron information */
-        $this->_newMessage('63');
-        $this->_addFixedOption($this->language, 3);
-        $this->_addFixedOption($this->_datestamp(), 18);
-        $this->_addFixedOption(sprintf("%-10s",$summary[$type]), 10);
-        $this->_addVarOption('AO',$this->AO);
-        $this->_addVarOption('AA',$this->patron);
-        $this->_addVarOption('AC',$this->AC, true);
-        $this->_addVarOption('AD',$this->patronpwd, true);
-        $this->_addVarOption('BP',$start, true); /* old function version used padded 5 digits, not sure why */
-        $this->_addVarOption('BQ',$end, true); /* old function version used padded 5 digits, not sure why */
-        return $this->_returnMessage();
-    }
-
-    function msgEndPatronSession() 
-    {
-        /*  End Patron Session, should be sent before switching to a new patron. (35) - untested */
-
-        $this->_newMessage('35');
-        $this->_addFixedOption($this->_datestamp(), 18);
-        $this->_addVarOption('AO',$this->AO);
-        $this->_addVarOption('AA',$this->patron);
-        $this->_addVarOption('AC',$this->AC, true);
-        $this->_addVarOption('AD',$this->patronpwd, true);
-        return $this->_returnMessage();
-    }
-    
-    /* Fee paid function should go here */
-    function msgFeePaid ($feeType, $pmtType, $pmtAmount, $curType = 'USD', $feeId = '', $transId = '') 
-    {
-        /* Fee payment function (37) - untested */
-        /* Fee Types: */
-        /* 01 other/unknown */
-        /* 02 administrative */
-        /* 03 damage */
-        /* 04 overdue */
-        /* 05 processing */
-        /* 06 rental*/
-        /* 07 replacement */
-        /* 08 computer access charge */
-        /* 09 hold fee */
-
-        /* Value Payment Type */
-        /* 00   cash */
-        /* 01   VISA */
-        /* 02   credit card */
-        
-        if (!is_numeric($feeType) || $feeType > 99 || $feeType < 1) {
-            /* not a valid fee type - exit */
-            $this->_debugmsg( "SIP2: (msgFeePaid) Invalid fee type: {$feeType}");
-            return false;
-        }
-
-        if (!is_numeric($pmtType) || $pmtType > 99 || $pmtType < 0) {
-            /* not a valid payment type - exit */
-            $this->_debugmsg( "SIP2: (msgFeePaid) Invalid payment type: {$pmtType}");
-            return false;
-        }
-        
-        $this->_newMessage('37');
-        $this->_addFixedOption($this->_datestamp(), 18);
-        $this->_addFixedOption(sprintf('%02d', $feeType), 2);
-        $this->_addFixedOption(sprintf('%02d', $pmtType), 2);
-        $this->_addFixedOption($curType, 3); 
-        $this->_addVarOption('BV',$pmtAmount); /* due to currency format localization, it is up to the programmer to properly format their payment amount */
-        $this->_addVarOption('AO',$this->AO);
-        $this->_addVarOption('AA',$this->patron);
-        $this->_addVarOption('AC',$this->AC, true);
-        $this->_addVarOption('AD',$this->patronpwd, true);
-        $this->_addVarOption('CG',$feeId, true);
-        $this->_addVarOption('BK',$transId, true);
-        
-        return $this->_returnMessage();
-    }
-    
-    function msgItemInformation($item) 
-    {
-
-        $this->_newMessage('17');
-        $this->_addFixedOption($this->_datestamp(), 18);
-        $this->_addVarOption('AO',$this->AO);
-        $this->_addVarOption('AB',$item);
-        $this->_addVarOption('AC',$this->AC, true);
-        return $this->_returnMessage();
-        
-    }
-
-    function msgItemStatus ($item, $itmProp = '') 
-    {
-        /* Item status update function (19) - untested  */
-
-        $this->_newMessage('19');
-        $this->_addFixedOption($this->_datestamp(), 18);
-        $this->_addVarOption('AO',$this->AO);
-        $this->_addVarOption('AB',$item);
-        $this->_addVarOption('AC',$this->AC, true);
-        $this->_addVarOption('CH',$itmProp);
-        return $this->_returnMessage();
-    }
-    
-    function msgPatronEnable () 
-    {
-        /* Patron Enable function (25) - untested */
-        /*  This message can be used by the SC to re-enable cancelled patrons. It should only be used for system testing and validation. */
-        $this->_newMessage('25');
-        $this->_addFixedOption($this->_datestamp(), 18);
-        $this->_addVarOption('AO',$this->AO);
-        $this->_addVarOption('AA',$this->patron);
-        $this->_addVarOption('AC',$this->AC, true);
-        $this->_addVarOption('AD',$this->patronpwd, true);
-        return $this->_returnMessage();
-
-    }
-    
-    function msgHold($mode, $expDate = '', $holdtype = '', $item = '', $title = '', $fee='N', $pkupLocation = '') 
-    {
-        /* mode validity check */
-        /* 
-        * - remove hold
-        * + place hold
-        * * modify hold
-        */
-        if (strpos('-+*',$mode) === false) {
-            /* not a valid mode - exit */
-            $this->_debugmsg( "SIP2: Invalid hold mode: {$mode}");
-            return false;
-        }
-        
-        if ($holdtype != '' && ($holdtype < 1 || $holdtype > 9)) {
-            /*
-        * Valid hold types range from 1 - 9 
-        * 1   other
-        * 2   any copy of title
-        * 3   specific copy
-        * 4   any copy at a single branch or location
-        */
-            $this->_debugmsg( "SIP2: Invalid hold type code: {$holdtype}");
-            return false;
-        }
-
-        $this->_newMessage('15');
-        $this->_addFixedOption($mode, 1);
-        $this->_addFixedOption($this->_datestamp(), 18);
-        if ($expDate != '') {
-            /* hold expiration date,  due to the use of the datestamp function, we have to check here for empty value. when datestamp is passed an empty value it will generate a current datestamp */
-            $this->_addVarOption('BW', $this->_datestamp($expDate), true); /*spec says this is fixed field, but it behaves like a var field and is optional... */
-        }
-        $this->_addVarOption('BS',$pkupLocation, true);
-        $this->_addVarOption('BY',$holdtype, true);
-        $this->_addVarOption('AO',$this->AO);
-        $this->_addVarOption('AA',$this->patron);
-        $this->_addVarOption('AD',$this->patronpwd, true);
-        $this->_addVarOption('AB',$item, true);
-        $this->_addVarOption('AJ',$title, true);
-        $this->_addVarOption('AC',$this->AC, true);
-        $this->_addVarOption('BO',$fee, true); /* Y when user has agreed to a fee notice */
-        
-        return $this->_returnMessage();
-
-    }
-
-    function msgRenew($item = '', $title = '', $nbDateDue = '', $itmProp = '', $fee= 'N', $noBlock = 'N', $thirdParty = 'N') 
-    {
-        /* renew a single item (29) - untested */
-        $this->_newMessage('29');
-        $this->_addFixedOption($thirdParty, 1);
-        $this->_addFixedOption($noBlock, 1);
-        $this->_addFixedOption($this->_datestamp(), 18);
-        if ($nbDateDue != '') {
-            /* override default date due */
-            $this->_addFixedOption($this->_datestamp($nbDateDue), 18);
-        } else {
-            /* send a blank date due to allow ACS to use default date due computed for item */
-            $this->_addFixedOption('', 18);
-        }
-        $this->_addVarOption('AO',$this->AO);
-        $this->_addVarOption('AA',$this->patron);
-        $this->_addVarOption('AD',$this->patronpwd, true);
-        $this->_addVarOption('AB',$item, true);
-        $this->_addVarOption('AJ',$title, true);
-        $this->_addVarOption('AC',$this->AC, true);
-        $this->_addVarOption('CH',$itmProp, true);
-        $this->_addVarOption('BO',$fee, true); /* Y or N */
-        
-        return $this->_returnMessage();
-    }
-
-    function msgRenewAll($fee = 'N') 
-    {
-        /* renew all items for a patron (65) - untested */
-        $this->_newMessage('65');
-        $this->_addVarOption('AO',$this->AO);
-        $this->_addVarOption('AA',$this->patron);
-        $this->_addVarOption('AD',$this->patronpwd, true);
-        $this->_addVarOption('AC',$this->AC, true);
-        $this->_addVarOption('BO',$fee, true); /* Y or N */
-
-        return $this->_returnMessage();
-    }
-    
-    function parsePatronStatusResponse($response) 
-    {
-        $result['fixed'] = 
-        array( 
-        'PatronStatus'      => substr($response, 2, 14),
-        'Language'          => substr($response, 16, 3),
-        'TransactionDate'   => substr($response, 19, 18),
-        );    
-
-        $result['variable'] = $this->_parsevariabledata($response, 37);
-        return $result;
-    }
-
-    function parseCheckoutResponse($response) 
-    {
-        $result['fixed'] = 
-        array( 
-        'Ok'                => substr($response,2,1),
-        'RenewalOk'         => substr($response,3,1),
-        'Magnetic'          => substr($response,4,1),
-        'Desensitize'       => substr($response,5,1),
-        'TransactionDate'   => substr($response,6,18),
-        );
-        
-        $result['variable'] = $this->_parsevariabledata($response, 24);
-        return $result;
-
-    }
-
-    function parseCheckinResponse($response) 
-    {
-        $result['fixed'] = 
-        array( 
-        'Ok'                => substr($response,2,1),
-        'Resensitize'       => substr($response,3,1),
-        'Magnetic'          => substr($response,4,1),
-        'Alert'             => substr($response,5,1),
-        'TransactionDate'   => substr($response,6,18),
-        );
-        
-        $result['variable'] = $this->_parsevariabledata($response, 24);
-        return $result;
-
-    }
-
-    function parseACSStatusResponse($response) 
-    {
-        $result['fixed'] = 
-        array( 
-        'Online'            => substr($response, 2, 1),
-        'Checkin'           => substr($response, 3, 1),  /* is Checkin by the SC allowed ?*/
-        'Checkout'          => substr($response, 4, 1),  /* is Checkout by the SC allowed ?*/
-        'Renewal'			=> substr($response, 5, 1),  /* renewal allowed? */
-        'PatronUpdate'      => substr($response, 6, 1),  /* is patron status updating by the SC allowed ? (status update ok)*/
-        'Offline'           => substr($response, 7, 1),
-        'Timeout'           => substr($response, 8, 3),
-        'Retries'           => substr($response, 11, 3), 
-        'TransactionDate'   => substr($response, 14, 18),
-        'Protocol'          => substr($response, 32, 4),
-        );
-        
-        $result['variable'] = $this->_parsevariabledata($response, 36);
-        return $result;
-    }
-
-    function parseLoginResponse($response) 
-    {
-        $result['fixed'] = 
-        array( 
-        'Ok'                => substr($response, 2, 1),
-        );
-        $result['variable'] = array();
-        return $result;
-    }
-
-    function parsePatronInfoResponse($response) 
-    {
-        
-        $result['fixed'] = 
-        array( 
-        'PatronStatus'      => substr($response, 2, 14),
-        'Language'          => substr($response, 16, 3),
-        'TransactionDate'   => substr($response, 19, 18),
-        'HoldCount'         => intval (substr($response, 37, 4)),
-        'OverdueCount'      => intval (substr($response, 41, 4)),
-        'ChargedCount'      => intval (substr($response, 45, 4)),
-        'FineCount'         => intval (substr($response, 49, 4)),
-        'RecallCount'       => intval (substr($response, 53, 4)),
-        'UnavailableCount'  => intval (substr($response, 57, 4))
-        );    
-
-        $result['variable'] = $this->_parsevariabledata($response, 61);
-        return $result;
-    }
-
-    function parseEndSessionResponse($response) 
-    {
-        /*   Response example:  36Y20080228 145537AOWOHLERS|AAX00000000|AY9AZF474   */
-        
-        $result['fixed'] = 
-        array( 
-        'EndSession'        => substr($response, 2, 1),
-        'TransactionDate'   => substr($response, 3, 18),
-        );    
-
-
-        $result['variable'] = $this->_parsevariabledata($response, 21);
-        
-        return $result;
-    }
-    
-    function parseFeePaidResponse($response) 
-    {
-        $result['fixed'] = 
-        array( 
-        'PaymentAccepted'   => substr($response, 2, 1),
-        'TransactionDate'   => substr($response, 3, 18),
-        );    
-
-        $result['variable'] = $this->_parsevariabledata($response, 21);
-        return $result;
-        
-    }
-
-    function parseItemInfoResponse($response) 
-    {
-        $result['fixed'] = 
-        array( 
-        'CirculationStatus' => intval (substr($response, 2, 2)),
-        'SecurityMarker'    => intval (substr($response, 4, 2)),
-        'FeeType'           => intval (substr($response, 6, 2)),
-        'TransactionDate'   => substr($response, 8, 18),
-        );    
-
-        $result['variable'] = $this->_parsevariabledata($response, 26);
-
-        return $result;
-    }
-
-    function parseItemStatusResponse($response) 
-    {
-        $result['fixed'] = 
-        array( 
-        'PropertiesOk'      => substr($response, 2, 1),
-        'TransactionDate'   => substr($response, 3, 18),
-        );    
-
-        $result['variable'] = $this->_parsevariabledata($response, 21);
-        return $result;
-        
-    }
-
-    function parsePatronEnableResponse($response) 
-    {
-        $result['fixed'] = 
-        array( 
-        'PatronStatus'      => substr($response, 2, 14),
-        'Language'          => substr($response, 16, 3),
-        'TransactionDate'   => substr($response, 19, 18),
-        );    
-
-        $result['variable'] = $this->_parsevariabledata($response, 37);
-        return $result;
-        
-    }
-
-    function parseHoldResponse($response) 
-    {
-
-        $result['fixed'] = 
-        array( 
-        'Ok'                => substr($response, 2, 1),
-        'available'         => substr($response, 3, 1),
-        'TransactionDate'   => substr($response, 4, 18),
-        'ExpirationDate'    => substr($response, 22, 18)			
-        );    
-
-
-        $result['variable'] = $this->_parsevariabledata($response, 40);
-
-        return $result;
-    }	
-    
-    
-    function parseRenewResponse($response) 
-    {
-        /* Response Example:  300NUU20080228    222232AOWOHLERS|AAX00000241|ABM02400028262|AJFolksongs of Britain and Ireland|AH5/23/2008,23:59|CH|AFOverride required to exceed renewal limit.|AY1AZCDA5 */
-        $result['fixed'] = 
-        array( 
-        'Ok'                => substr($response, 2, 1),
-        'RenewalOk'         => substr($response, 3, 1),
-        'Magnetic'          => substr($response, 4, 1),
-        'Desensitize'       => substr($response, 5, 1),
-        'TransactionDate'   => substr($response, 6, 18),
-        );    
-
-
-        $result['variable'] = $this->_parsevariabledata($response, 24);
-
-        return $result;
-    }
-    
-    function parseRenewAllResponse($response) 
-    {
-        $result['fixed'] = 
-        array( 
-        'Ok'                => substr($response, 2, 1),
-        'Renewed'           => substr($response, 3, 4),
-        'Unrenewed'         => substr($response, 7, 4),
-        'TransactionDate'   => substr($response, 11, 18),
-        );    
-
-
-        $result['variable'] = $this->_parsevariabledata($response, 29);
-
-        return $result;
-    }
-
-
-    
-    
-    function get_message ($message) 
-    {
-        /* sends the current message, and gets the response */
-        $result     = '';
-        $terminator = '';
-        $nr         = '';
-        
-        $this->_debugmsg('SIP2: Sending SIP2 request...');
-        socket_write($this->socket, $message, strlen($message));
-
-        $this->_debugmsg('SIP2: Request Sent, Reading response');
-
-        while ($terminator != "\x0D" && $nr !== FALSE) {
-            $nr = socket_recv($this->socket,$terminator,1,0);
-            $result = $result . $terminator;
-        }
-
-        $this->_debugmsg("SIP2: {$result}");
-
-        /* test message for CRC validity */
-        if ($this->_check_crc($result)) {
-            /* reset the retry counter on successful send */
-            $this->retry=0;
-            $this->_debugmsg("SIP2: Message from ACS passed CRC check");
-        } else {
-            /* CRC check failed, request a resend */
-            $this->retry++;
-            if ($this->retry < $this->maxretry) {
-                /* try again */
-                $this->_debugmsg("SIP2: Message failed CRC check, retrying ({$this->retry})");
-                
-                $this->get_message($message);
-            } else {
-                /* give up */
-                $this->_debugmsg("SIP2: Failed to get valid CRC after {$this->maxretry} retries.");
-                return false;
-            }
-        }
-        return $result;
-    }	
-
-    function connect() 
-    {
-
-        /* Socket Communications  */
-        $this->_debugmsg( "SIP2: --- BEGIN SIP communication ---");  
-        
-        /* Get the IP address for the target host. */
-        $address = gethostbyname($this->hostname);
-
-        /* Create a TCP/IP socket. */
-        $this->socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
-
-        /* check for actual truly false result using ===*/
-        if ($this->socket === false) {
-            $this->_debugmsg( "SIP2: socket_create() failed: reason: " . socket_strerror($this->socket));
-            return false;
-        } else {
-            $this->_debugmsg( "SIP2: Socket Created" ); 
-        }
-        $this->_debugmsg( "SIP2: Attempting to connect to '$address' on port '{$this->port}'..."); 
-
-        /* open a connection to the host */
-        $result = socket_connect($this->socket, $address, $this->port);
-        if (!$result) {
-            $this->_debugmsg("SIP2: socket_connect() failed.\nReason: ($result) " . socket_strerror($result));
-        } else {
-            $this->_debugmsg( "SIP2: --- SOCKET READY ---" );
-        }
-        /* return the result from the socket connect */
-        return $result;
-        
-    }	
-    
-    function disconnect () 
-    {
-        /*  Close the socket */
-        socket_close($this->socket);
-    }
-
-    /* Core local utility functions */	
-    function _datestamp($timestamp = '') 
-    {
-        /* generate a SIP2 compatible datestamp */
-        /* From the spec:
-        * YYYYMMDDZZZZHHMMSS. 
-        * All dates and times are expressed according to the ANSI standard X3.30 for date and X3.43 for time. 
-        * The ZZZZ field should contain blanks (code $20) to represent local time. To represent universal time, 
-        *  a Z character(code $5A) should be put in the last (right hand) position of the ZZZZ field. 
-        * To represent other time zones the appropriate character should be used; a Q character (code $51) 
-        * should be put in the last (right hand) position of the ZZZZ field to represent Atlantic Standard Time. 
-        * When possible local time is the preferred format.
-        */
-        if ($timestamp != '') {
-            /* Generate a proper date time from the date provided */
-            return date('Ymd    His', $timestamp);
-        } else {
-            /* Current Date/Time */
-            return date('Ymd    His');
-        }
-    }
-
-    function _parsevariabledata($response, $start) 
-    {
-
-        $result = array();
-        $result['Raw'] = explode("|", substr($response,$start,-7));
-        foreach ($result['Raw'] as $item) {
-            $field = substr($item,0,2);
-            $value = substr($item,2);
-            /* SD returns some odd values on occasion, Unable to locate the purpose in spec, so I strip from 
-            * the parsed array. Orig values will remain in ['raw'] element
-            */
-            $clean = trim($value, "\x00..\x1F");
-            if (trim($clean) <> '') {
-                $result[$field][] = $clean;
-            }
-        }		
-        $result['AZ'][] = substr($response,-5);
-
-        return ($result);
-    }
-
-    function _crc($buf) 
-    {
-        /* Calculate CRC  */
-        $sum = 0;
-
-        $len = strlen($buf);
-        for ($n = 0; $n < $len; $n++) {
-            $sum = $sum + ord(substr($buf, $n, 1));
-        } 
-
-        $crc = ($sum & 0xFFFF) * -1;
-
-        /* 2008.03.15 - Fixed a bug that allowed the checksum to be larger then 4 digits */
-        return substr(sprintf ("%4X", $crc), -4, 4);
-    } /* end crc */	
-
-    function _getseqnum() 
-    {
-        /* Get a sequence number for the AY field */
-        /* valid numbers range 0-9 */
-        $this->seq++;
-        if ($this->seq > 9 ) {
-            $this->seq = 0;
-        }
-        return ($this->seq);
-    }
-    
-    function _debugmsg($message) 
-    {
-        /* custom debug function,  why repeat the check for the debug flag in code... */
-        if ($this->debug) { 
-            trigger_error( $message, E_USER_NOTICE); 
-        }	
-    }
-    
-    function _check_crc($message) 
-    {
-        /* test the received message's CRC by generating our own CRC from the message */
-        $test = preg_split('/(.{4})$/',trim($message),2,PREG_SPLIT_DELIM_CAPTURE);
-
-        if ($this->_crc($test[0]) == $test[1]) {
-            return true;
-        } else {
-            return false;
-        }
-    }
-    
-    function _newMessage($code) 
-    {
-        /* resets the msgBuild variable to the value of $code, and clears the flag for fixed messages */
-        $this->noFixed  = false;
-        $this->msgBuild = $code;
-    }
-    
-    function _addFixedOption($value, $len) 
-    {
-        /* adds a fixed length option to the msgBuild IF no variable options have been added. */
-        if ( $this->noFixed ) {
-            return false;
-        } else {
-            $this->msgBuild .= sprintf("%{$len}s", substr($value,0,$len));
-            return true;
-        }
-    }
-    
-    function _addVarOption($field, $value, $optional = false) 
-    {
-        /* adds a variable length option to the message, and also prevents adding additional fixed fields */
-        if ($optional == true && $value == '') {
-            /* skipped */
-            $this->_debugmsg( "SIP2: Skipping optional field {$field}");
-        } else {
-            $this->noFixed  = true; /* no more fixed for this message */
-            $this->msgBuild .= $field . substr($value, 0, 255) . $this->fldTerminator;
-        }
-        return true;
-    }
-    
-    function _returnMessage($withSeq = true, $withCrc = true) 
-    {
-        /* Finalizes the message and returns it.  Message will remain in msgBuild until newMessage is called */
-        if ($withSeq) {
-            $this->msgBuild .= 'AY' . $this->_getseqnum();
-        }
-        if ($withCrc) {
-            $this->msgBuild .= 'AZ';
-            $this->msgBuild .= $this->_crc($this->msgBuild);
-        }
-        $this->msgBuild .= $this->msgTerminator;
-
-        return $this->msgBuild;
-    }
-    
-}
-
-?>
diff --git a/src/Exception/LogicException.php b/src/Exception/LogicException.php
new file mode 100644
index 0000000..73f6906
--- /dev/null
+++ b/src/Exception/LogicException.php
@@ -0,0 +1,13 @@
+<?php
+
+namespace cap60552\SIP2\Exception;
+
+/**
+ * LogicException represents an integration problem - the code is being used incorrectly
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class LogicException extends \LogicException implements SIP2ClientException
+{
+}
diff --git a/src/Exception/RuntimeException.php b/src/Exception/RuntimeException.php
new file mode 100644
index 0000000..1019a4e
--- /dev/null
+++ b/src/Exception/RuntimeException.php
@@ -0,0 +1,14 @@
+<?php
+
+namespace cap60552\SIP2\Exception;
+
+/**
+ * RuntimeException is fired for conditions which arise only at runtime, e.g. external services being down
+ * bad CRCs from remote services
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class RuntimeException extends \RuntimeException implements SIP2ClientException
+{
+}
diff --git a/src/Exception/SIP2ClientException.php b/src/Exception/SIP2ClientException.php
new file mode 100644
index 0000000..09a43bf
--- /dev/null
+++ b/src/Exception/SIP2ClientException.php
@@ -0,0 +1,14 @@
+<?php
+
+namespace cap60552\SIP2\Exception;
+
+/**
+ * SIP2ClientException is just a 'marker interface' that all exceptions thrown by SIP2Client will
+ * implement, allowing integrators to catch all exceptions
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+interface SIP2ClientException
+{
+}
diff --git a/src/Request/BlockPatronRequest.php b/src/Request/BlockPatronRequest.php
new file mode 100644
index 0000000..7276eaa
--- /dev/null
+++ b/src/Request/BlockPatronRequest.php
@@ -0,0 +1,43 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+/**
+ * BlockPatronRequest requests that the patron card be blocked by the ACS. This is, for example, sent when the patron
+ * is detected tampering with the SC or when a patron forgets to take their card. The ACS should invalidate the
+ * patron’s card and respond with a Patron Status Response message. The ACS could also notify the library staff
+ * that the card has been blocked.
+ *
+ * @method setCardRetained(string $yn)
+ * @method setInstitutionId(string $institutionId)
+ * @method setMessage(string $message)
+ * @method setPatronIdentifier(string $patron)
+ * @method setTerminalPassword(string $terminalPassword)
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class BlockPatronRequest extends SIP2Request
+{
+    protected $var = [
+        'CardRetained' => ['type' => 'YN', 'default' => 'N'],
+        'InstitutionId' => [],
+        'Message' => ['default' => ''],
+        'PatronIdentifier' => [],
+        'TerminalPassword' => ['default' => ''],
+    ];
+
+    public function getMessageString($withSeq = true, $withCrc = true): string
+    {
+        $this->newMessage('01');
+        $this->addFixedOption($this->getVariable('CardRetained'), 1);
+        $this->addFixedOption($this->datestamp(), 18);
+        $this->addVarOption('AO', $this->getVariable('InstitutionId'));
+        $this->addVarOption('AL', $this->getVariable('Message'));
+        $this->addVarOption('AA', $this->getVariable('PatronIdentifier'));
+        $this->addVarOption('AC', $this->getVariable('TerminalPassword'));
+
+        return $this->returnMessage($withSeq, $withCrc);
+    }
+}
diff --git a/src/Request/CheckInRequest.php b/src/Request/CheckInRequest.php
new file mode 100644
index 0000000..159b4fc
--- /dev/null
+++ b/src/Request/CheckInRequest.php
@@ -0,0 +1,53 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+/**
+ * CheckInRequest is used by the SC to request to check in an item, and also to cancel a Checkout request that did not
+ * successfully complete. The ACS must respond to this command with a Checkin Response message.
+ *
+ * You must call setItemIdentifier() to provide the barcode of the item you're checking in. Other variables
+ * are optional or set automatically by the SIP2Client
+ *
+ * @method setNoBlock(string $yn)
+ * @method setItemReturnDate(string $timestamp)
+ * @method setItemLocation(string $location)
+ * @method setInstitutionId(string $institutionId)
+ * @method setItemIdentifier(string $itemIdentifier)
+ * @method setTerminalPassword(string $terminalPassword)
+ * @method setItemProperties(string $itemProperties)
+ * @method setCancel(string $yn)
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class CheckInRequest extends SIP2Request
+{
+    protected $var = [
+        'NoBlock' => ['type' => 'YN', 'default' => 'N'],
+        'ItemReturnDate' => ['type' => 'timestamp', 'default' => ''],
+        'ItemLocation' => ['default' => ''],
+        'InstitutionId' => [],
+        'ItemIdentifier' => [],
+        'TerminalPassword' => ['default' => ''],
+        'ItemProperties' => ['default' => ''],
+        'Cancel' => ['type' => 'YN', 'default' => 'N'],
+    ];
+
+    public function getMessageString($withSeq = true, $withCrc = true): string
+    {
+        $this->newMessage('09');
+        $this->addFixedOption($this->getVariable('NoBlock'), 1);
+        $this->addFixedOption($this->datestamp(), 18);
+        $this->addFixedOption($this->getVariable('ItemReturnDate'), 18);
+        $this->addVarOption('AP', $this->getVariable('ItemLocation'));
+        $this->addVarOption('AO', $this->getVariable('InstitutionId'));
+        $this->addVarOption('AB', $this->getVariable('ItemIdentifier'));
+        $this->addVarOption('AC', $this->getVariable('TerminalPassword'));
+        $this->addVarOption('CH', $this->getVariable('ItemProperties'), true);
+        $this->addVarOption('BI', $this->getVariable('Cancel'), true);
+
+        return $this->returnMessage($withSeq, $withCrc);
+    }
+}
diff --git a/src/Request/CheckOutRequest.php b/src/Request/CheckOutRequest.php
new file mode 100644
index 0000000..50c0429
--- /dev/null
+++ b/src/Request/CheckOutRequest.php
@@ -0,0 +1,63 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+/**
+ * CheckOutRequest is used by the SC to request to check out an item, and also to cancel a CheckIn request that did
+ * not successfully complete. The ACS must respond to this command with a CheckOut Response message.
+ *
+ * You must call setItemIdentifier() to provide the barcode of the item you're checking out. Other variables
+ * are optional or set automatically by the SIP2Client
+ *
+ * @method setSCRenewal(string $yn)
+ * @method setNoBlock(string $yn)
+ * @method setNBDateDue(string $timestamp)
+ * @method setInstitutionId(string $institutionId)
+ * @method setPatronIdentifier(string $patron)
+ * @method setItemIdentifier(string $itemIdentifier)
+ * @method setTerminalPassword(string $terminalPassword)
+ * @method setItemProperties(string $itemProperties)
+ * @method setPatronPassword(string $patronPassword)
+ * @method setFeeAcknowledged(string $yn)
+ * @method setCancel(string $yn)
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class CheckOutRequest extends SIP2Request
+{
+    protected $var = [
+        'SCRenewal' => ['type' => 'YUN', 'default' => 'N'],
+        'NoBlock' => ['type' => 'YN', 'default' => 'N'],
+        'NBDateDue' => ['type' => 'timestamp', 'default' => ''],
+        'InstitutionId' => [],
+        'PatronIdentifier' => [],
+        'ItemIdentifier' => [],
+        'TerminalPassword' => ['default' => ''],
+        'ItemProperties' => ['default' => ''],
+        'PatronPassword' => ['default' => ''],
+        'FeeAcknowledged' => ['type' => 'YN', 'default' => 'N'],
+        'Cancel' => ['type' => 'YN', 'default' => 'N'],
+    ];
+
+    public function getMessageString($withSeq = true, $withCrc = true): string
+    {
+        $this->newMessage('11');
+        $this->addFixedOption($this->getVariable('SCRenewal'), 1);
+        $this->addFixedOption($this->getVariable('NoBlock'), 1);
+        $this->addFixedOption($this->datestamp(), 18);
+        $this->addFixedOption($this->getVariable('NBDateDue'), 18);
+
+        $this->addVarOption('AO', $this->getVariable('InstitutionId'));
+        $this->addVarOption('AA', $this->getVariable('PatronIdentifier'));
+        $this->addVarOption('AB', $this->getVariable('ItemIdentifier'));
+        $this->addVarOption('AC', $this->getVariable('TerminalPassword'));
+        $this->addVarOption('CH', $this->getVariable('ItemProperties'), true);
+        $this->addVarOption('AD', $this->getVariable('PatronPassword'), true);
+        $this->addVarOption('BO', $this->getVariable('FeeAcknowledged'), true);
+        $this->addVarOption('BI', $this->getVariable('Cancel'), true);
+
+        return $this->returnMessage($withSeq, $withCrc);
+    }
+}
diff --git a/src/Request/EndPatronSessionRequest.php b/src/Request/EndPatronSessionRequest.php
new file mode 100644
index 0000000..e4b2af0
--- /dev/null
+++ b/src/Request/EndPatronSessionRequest.php
@@ -0,0 +1,39 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+/**
+ * EndPatronSessionRequest will be sent when a patron has completed all of their transactions. The ACS may, upon
+ * receipt of this command, close any open files or deallocate data structures pertaining to that patron. The ACS
+ * should respond with an End Session Response message.
+ *
+ * @method setInstitutionId(string $institutionId)
+ * @method setPatronIdentifier(string $patron)
+ * @method setTerminalPassword(string $terminalPassword)
+ * @method setPatronPassword(string $patronPassword)
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class EndPatronSessionRequest extends SIP2Request
+{
+    protected $var = [
+        'InstitutionId' => [],
+        'PatronIdentifier' => [],
+        'TerminalPassword' => ['default' => ''],
+        'PatronPassword' => ['default' => ''],
+    ];
+
+    public function getMessageString($withSeq = true, $withCrc = true): string
+    {
+        $this->newMessage('35');
+        $this->addFixedOption($this->datestamp(), 18);
+        $this->addVarOption('AO', $this->getVariable('InstitutionId'));
+        $this->addVarOption('AA', $this->getVariable('PatronIdentifier'));
+        $this->addVarOption('AC', $this->getVariable('TerminalPassword'), true);
+        $this->addVarOption('AD', $this->getVariable('PatronPassword'), true);
+
+        return $this->returnMessage($withSeq, $withCrc);
+    }
+}
diff --git a/src/Request/FeePaidRequest.php b/src/Request/FeePaidRequest.php
new file mode 100644
index 0000000..1dbb858
--- /dev/null
+++ b/src/Request/FeePaidRequest.php
@@ -0,0 +1,76 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+/**
+ * FeePaidRequest can be used to notify the ACS that a fee has been collected from the patron. The ACS should record
+ * this information in their database and respond with a Fee Paid Response message.
+ *
+ * The FeeType can be one of
+ *    01 other/unknown
+ *    02 administrative
+ *    03 damage
+ *    04 overdue
+ *    05 processing
+ *    06 rental
+ *    07 replacement
+ *    08 computer access charge
+ *    09 hold fee
+ * The PaymentType can be one of
+ *    00 cash
+ *    01 visa
+ *    02 credit card
+ *
+ * CurrencyType is a 3-letter code following ISO Standard 4217:1995
+ *
+ * @method setFeeType(string $feeType)
+ * @method setPaymentType(string $paymentType)
+ * @method setCurrencyType(string $currencyCode)
+ * @method setPaymentAmount(string $amount)
+ * @method setInstitutionId(string $institutionId)
+ * @method setPatronIdentifier(string $patron)
+ * @method setTerminalPassword(string $terminalPassword)
+ * @method setPatronPassword(string $patronPassword)
+ * @method setFeeIdentifier(string $feeId)
+ * @method setTransactionIdentifier(string $transactionId)
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class FeePaidRequest extends SIP2Request
+{
+    protected $var = [
+        'FeeType' => ['type' => 'nn'],
+        'PaymentType' => ['type' => 'nn'],
+        'CurrencyType' => ['default' => 'USD'],
+        'PaymentAmount' => [],
+        'InstitutionId' => [],
+        'PatronIdentifier' => [],
+        'TerminalPassword' => ['default' => ''],
+        'PatronPassword' => ['default' => ''],
+        'FeeIdentifier' => ['default' => ''],
+        'TransactionIdentifier' => ['default' => ''],
+    ];
+
+    public function getMessageString($withSeq = true, $withCrc = true): string
+    {
+        $this->newMessage('37');
+        $this->addFixedOption($this->datestamp(), 18);
+        $this->addFixedOption(sprintf('%02d', (string)$this->getVariable('FeeType')), 2);
+        $this->addFixedOption(sprintf('%02d', (string)$this->getVariable('PaymentType')), 2);
+        $this->addFixedOption($this->getVariable('CurrencyType'), 3);
+
+        // due to currency format localization, it is up to the programmer
+        // to properly format their payment amount
+        $this->addVarOption('BV', $this->getVariable('PaymentAmount'));
+        $this->addVarOption('AO', $this->getVariable('InstitutionId'));
+        $this->addVarOption('AA', $this->getVariable('PatronIdentifier'));
+        $this->addVarOption('AC', $this->getVariable('TerminalPassword'));
+        $this->addVarOption('AD', $this->getVariable('PatronPassword'), true);
+        $this->addVarOption('CG', $this->getVariable('FeeIdentifier'), true);
+        $this->addVarOption('BK', $this->getVariable('TransactionIdentifier'), true);
+
+        return $this->returnMessage($withSeq, $withCrc);
+    }
+}
diff --git a/src/Request/HoldRequest.php b/src/Request/HoldRequest.php
new file mode 100644
index 0000000..27e4474
--- /dev/null
+++ b/src/Request/HoldRequest.php
@@ -0,0 +1,81 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+/**
+ * HoldRequest is used to create, modify, or delete a hold. The ACS should respond with a Hold Response message.
+ * Either or both of the setItemIdentifier and setItemTitle methods must be called for the message to
+ * be useful.
+ *
+ * setHoldMode takes one of following values
+ *   HoldRequest::MODE_ADD
+ *   HoldRequest::MODE_DELETE
+ *   HoldRequest::MODE_CHANGE
+ *
+ * setHoldType takes one of following values:
+ *   HoldRequest::HOLD_OTHER
+ *   HoldRequest::HOLD_ANY_COPY
+ *   HoldRequest::HOLD_SPECIFIC_COPY
+ *   HoldRequest::HOLD_ANY_COPY_AT_LOCATION
+ *
+ * @method setHoldMode(string $mode)
+ * @method setExpiryDate(string $timestamp)
+ * @method setPickupLocation(string $location)
+ * @method setHoldType(string $type)
+ * @method setInstitutionId(string $institutionId)
+ * @method setPatronIdentifier(string $patron)
+ * @method setPatronPassword(string $patronPassword)
+ * @method setItemIdentifier(string $itemIdentifier)
+ * @method setItemTitle(string $itemTitle)
+ * @method setTerminalPassword(string $terminalPassword)
+ * @method setFeeAcknowledged(string $yn)
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class HoldRequest extends SIP2Request
+{
+    const MODE_ADD = '+';
+    const MODE_DELETE = '-';
+    const MODE_CHANGE = '*';
+
+    const HOLD_OTHER = 1;
+    const HOLD_ANY_COPY = 2;
+    const HOLD_SPECIFIC_COPY = 3;
+    const HOLD_ANY_COPY_AT_LOCATION = 4;
+
+    protected $var = [
+        'HoldMode' => ['type' => 'regex/[\-\+\*]/'],
+        'ExpiryDate' => ['type' => 'timestamp', 'default' => ''],
+        'PickupLocation' => ['default' => ''],
+        'HoldType' => ['type' => 'n', 'default' => ''],
+        'InstitutionId' => [],
+        'PatronIdentifier' => [],
+        'PatronPassword' => ['default' => ''],
+        'ItemIdentifier' => ['default' => ''],
+        'ItemTitle' => ['default' => ''],
+        'TerminalPassword' => ['default' => ''],
+        'FeeAcknowledged' => ['type' => 'YN', 'default' => 'N'],
+    ];
+
+    public function getMessageString($withSeq = true, $withCrc = true): string
+    {
+        $this->newMessage('15');
+        $this->addFixedOption($this->getVariable('HoldMode'), 1);
+        $this->addFixedOption($this->datestamp(), 18);
+
+        $this->addVarOption('BW', $this->getVariable('ExpiryDate'), true);
+        $this->addVarOption('BS', $this->getVariable('PickupLocation'), true);
+        $this->addVarOption('BY', $this->getVariable('HoldType'), true);
+        $this->addVarOption('AO', $this->getVariable('InstitutionId'));
+        $this->addVarOption('AA', $this->getVariable('PatronIdentifier'));
+        $this->addVarOption('AD', $this->getVariable('PatronPassword'), true);
+        $this->addVarOption('AB', $this->getVariable('ItemIdentifier'), true);
+        $this->addVarOption('AJ', $this->getVariable('ItemTitle'), true);
+        $this->addVarOption('AC', $this->getVariable('TerminalPassword'), true);
+        $this->addVarOption('BO', $this->getVariable('FeeAcknowledged'), true);
+
+        return $this->returnMessage($withSeq, $withCrc);
+    }
+}
diff --git a/src/Request/ItemInformationRequest.php b/src/Request/ItemInformationRequest.php
new file mode 100644
index 0000000..5c02800
--- /dev/null
+++ b/src/Request/ItemInformationRequest.php
@@ -0,0 +1,35 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+/**
+ * ItemInformationRequest may be used to request item information. The ACS should respond with the Item Information
+ * Response message.
+ *
+ * @method setInstitutionId(string $institutionId)
+ * @method setItemIdentifier(string $itemIdentifier)
+ * @method setTerminalPassword(string $terminalPassword)
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class ItemInformationRequest extends SIP2Request
+{
+    protected $var = [
+        'InstitutionId' => [],
+        'ItemIdentifier' => [],
+        'TerminalPassword' => ['default' => ''],
+    ];
+
+    public function getMessageString($withSeq = true, $withCrc = true): string
+    {
+        $this->newMessage('17');
+        $this->addFixedOption($this->datestamp(), 18);
+        $this->addVarOption('AO', $this->getVariable('InstitutionId'));
+        $this->addVarOption('AB', $this->getVariable('ItemIdentifier'));
+        $this->addVarOption('AC', $this->getVariable('TerminalPassword'));
+
+        return $this->returnMessage($withSeq, $withCrc);
+    }
+}
diff --git a/src/Request/ItemStatusUpdateRequest.php b/src/Request/ItemStatusUpdateRequest.php
new file mode 100644
index 0000000..9d24703
--- /dev/null
+++ b/src/Request/ItemStatusUpdateRequest.php
@@ -0,0 +1,39 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+/**
+ * ItemStatusUpdateRequest can be used to send item information to the ACS, without having to do a Checkout or Checkin
+ * operation. The item properties could be stored on the ACS’s database. The ACS should respond with an Item
+ * Status Update Response message.
+ *
+ * @method setInstitutionId(string $institutionId)
+ * @method setItemIdentifier(string $itemIdentifier)
+ * @method setTerminalPassword(string $terminalPassword)
+ * @method setItemProperties(string $itemProperties)
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class ItemStatusUpdateRequest extends SIP2Request
+{
+    protected $var = [
+        'InstitutionId' => [],
+        'ItemIdentifier' => [],
+        'TerminalPassword' => ['default' => ''],
+        'ItemProperties' => ['default' => ''],
+    ];
+
+    public function getMessageString($withSeq = true, $withCrc = true): string
+    {
+        $this->newMessage('19');
+        $this->addFixedOption($this->datestamp(), 18);
+        $this->addVarOption('AO', $this->getVariable('InstitutionId'));
+        $this->addVarOption('AB', $this->getVariable('ItemIdentifier'));
+        $this->addVarOption('AC', $this->getVariable('TerminalPassword'));
+        $this->addVarOption('CH', $this->getVariable('ItemProperties'), true);
+
+        return $this->returnMessage($withSeq, $withCrc);
+    }
+}
diff --git a/src/Request/LoginRequest.php b/src/Request/LoginRequest.php
new file mode 100644
index 0000000..cabbe4e
--- /dev/null
+++ b/src/Request/LoginRequest.php
@@ -0,0 +1,43 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+/**
+ * LoginRequest can be used to login to an ACS server program. The ACS should respond with the Login Response
+ * message. Whether to use this message or to use some other mechanism to login to the ACS is configurable on the
+ * SC. When this message is used, it will be the first message sent to the ACS.
+ *
+ * You must call setSIPLogin and setSIPPassword
+ *
+ * @method setUserIdAlgorithm(string $algorithm)
+ * @method setPasswordAlgorithm(string $algorithm)
+ * @method setSIPLogin(string $username)
+ * @method setSIPPassword(string $password)
+ * @method setLocation(string $location)
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class LoginRequest extends SIP2Request
+{
+    protected $var = [
+        'UserIdAlgorithm' => ['type' => 'n', 'default' => '0'],
+        'PasswordAlgorithm' => ['type' => 'n', 'default' => '0'],
+        'SIPLogin' => [],
+        'SIPPassword' => [],
+        'Location' => ['default' => '']
+    ];
+
+    public function getMessageString($withSeq = true, $withCrc = true): string
+    {
+        $this->newMessage('93');
+        $this->addFixedOption($this->getVariable('UserIdAlgorithm'), 1);
+        $this->addFixedOption($this->getVariable('PasswordAlgorithm'), 1);
+        $this->addVarOption('CN', $this->getVariable('SIPLogin'));
+        $this->addVarOption('CO', $this->getVariable('SIPPassword'));
+        $this->addVarOption('CP', $this->getVariable('Location'), true);
+
+        return $this->returnMessage($withSeq, $withCrc);
+    }
+}
diff --git a/src/Request/PatronEnableRequest.php b/src/Request/PatronEnableRequest.php
new file mode 100644
index 0000000..a9383e8
--- /dev/null
+++ b/src/Request/PatronEnableRequest.php
@@ -0,0 +1,38 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+/**
+ * PatronEnableRequest can be used by the SC to re-enable canceled patrons. It should only be used for system testing
+ * and validation. The ACS should respond with a Patron Enable Response message.
+ *
+ * @method setInstitutionId(string $institutionId)
+ * @method setPatronIdentifier(string $patron)
+ * @method setTerminalPassword(string $terminalPassword)
+ * @method setPatronPassword(string $patronPassword)
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class PatronEnableRequest extends SIP2Request
+{
+    protected $var = [
+        'InstitutionId' => [],
+        'PatronIdentifier' => [],
+        'TerminalPassword' => ['default' => ''],
+        'PatronPassword' => ['default' => ''],
+    ];
+
+    public function getMessageString($withSeq = true, $withCrc = true): string
+    {
+        $this->newMessage('25');
+        $this->addFixedOption($this->datestamp(), 18);
+        $this->addVarOption('AO', $this->getVariable('InstitutionId'));
+        $this->addVarOption('AA', $this->getVariable('PatronIdentifier'));
+        $this->addVarOption('AC', $this->getVariable('TerminalPassword'), true);
+        $this->addVarOption('AD', $this->getVariable('PatronPassword'), true);
+
+        return $this->returnMessage($withSeq, $withCrc);
+    }
+}
diff --git a/src/Request/PatronInformationRequest.php b/src/Request/PatronInformationRequest.php
new file mode 100644
index 0000000..4af02f9
--- /dev/null
+++ b/src/Request/PatronInformationRequest.php
@@ -0,0 +1,70 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+/**
+ * PatronInformationRequest is a superset of the Patron Status Request message. It should be used to request patron
+ * information. The ACS should respond with the Patron Information Response message.
+ *
+ * The setType() method accepts one of none, hold, overdue, charged, fine, recall and unavail
+ *
+ * @method setLanguage(string $languageCode)
+ * @method setType(string $informationType)
+ * @method setInstitutionId(string $institutionId)
+ * @method setPatronIdentifier(string $patron)
+ * @method setTerminalPassword(string $terminalPassword)
+ * @method setPatronPassword(string $patronPassword)
+ * @method setStart(string $start)
+ * @method setEnd(string $end)
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class PatronInformationRequest extends SIP2Request
+{
+    protected $var = [
+        'Language' => ['type' => 'nnn', 'default' => '001'],
+        'Type' => ['default' => 'none'],
+        'InstitutionId' => [],
+        'PatronIdentifier' => [],
+        'TerminalPassword' => ['default' => ''],
+        'PatronPassword' => ['default' => ''],
+        'Start' => ['default' => '1'],
+        'End' => ['default' => '5'],
+    ];
+
+    public function getMessageString($withSeq = true, $withCrc = true): string
+    {
+        /*
+        * According to the specification:
+        * Only one category of items should be  requested at a time, i.e. it would take 6 of these messages,
+        * each with a different position set to Y, to get all the detailed information about a patron's items.
+        */
+        $summary = [];
+        $summary['none'] = '      ';
+        $summary['hold'] = 'Y     ';
+        $summary['overdue'] = ' Y    ';
+        $summary['charged'] = '  Y   ';
+        $summary['fine'] = '   Y  ';
+        $summary['recall'] = '    Y ';
+        $summary['unavail'] = '     Y';
+
+        $type = $this->getVariable('Type');
+
+        $this->newMessage('63');
+        $this->addFixedOption($this->getVariable('Language'), 3);
+        $this->addFixedOption($this->datestamp(), 18);
+        $this->addFixedOption(sprintf("%-10s", $summary[$type]), 10);
+        $this->addVarOption('AO', $this->getVariable('InstitutionId'));
+        $this->addVarOption('AA', $this->getVariable('PatronIdentifier'));
+        $this->addVarOption('AC', $this->getVariable('TerminalPassword'));
+        $this->addVarOption('AD', $this->getVariable('PatronPassword'), true);
+        /* old function version used padded 5 digits, not sure why */
+        $this->addVarOption('BP', $this->getVariable('Start'), true);
+        /* old function version used padded 5 digits, not sure why */
+        $this->addVarOption('BQ', $this->getVariable('End'), true);
+
+        return $this->returnMessage($withSeq, $withCrc);
+    }
+}
diff --git a/src/Request/PatronStatusRequest.php b/src/Request/PatronStatusRequest.php
new file mode 100644
index 0000000..d353f27
--- /dev/null
+++ b/src/Request/PatronStatusRequest.php
@@ -0,0 +1,41 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+/**
+ * PatronStatusRequest is used by the client to request patron information from the SIP2 server. The service must
+ * respond to this command with a Patron Status Response message.
+ *
+ * @method setLanguage(string $languageCode)
+ * @method setInstitutionId(string $institutionId)
+ * @method setPatronIdentifier(string $patron)
+ * @method setTerminalPassword(string $terminalPassword)
+ * @method setPatronPassword(string $patronPassword)
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class PatronStatusRequest extends SIP2Request
+{
+    protected $var = [
+        'Language' => ['type' => 'nnn', 'default' => '001'],
+        'InstitutionId' => [],
+        'PatronIdentifier' => [],
+        'TerminalPassword' => ['default' => ''],
+        'PatronPassword' => ['default' => ''],
+    ];
+
+    public function getMessageString($withSeq = true, $withCrc = true): string
+    {
+        $this->newMessage('23');
+        $this->addFixedOption($this->getVariable('Language'), 3);
+        $this->addFixedOption($this->datestamp(), 18);
+        $this->addVarOption('AO', $this->getVariable('InstitutionId'));
+        $this->addVarOption('AA', $this->getVariable('PatronIdentifier'));
+        $this->addVarOption('AC', $this->getVariable('TerminalPassword'));
+        $this->addVarOption('AD', $this->getVariable('PatronPassword'), true);
+
+        return $this->returnMessage($withSeq, $withCrc);
+    }
+}
diff --git a/src/Request/RenewAllRequest.php b/src/Request/RenewAllRequest.php
new file mode 100644
index 0000000..8e60e11
--- /dev/null
+++ b/src/Request/RenewAllRequest.php
@@ -0,0 +1,40 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+/**
+ * RenewAllRequest is used to renew all items that the patron has checked out. The ACS should respond with a Renew All
+ * Response message.
+ *
+ * @method setInstitutionId(string $institutionId)
+ * @method setPatronIdentifier(string $patron)
+ * @method setPatronPassword(string $patronPassword)
+ * @method setTerminalPassword(string $terminalPassword)
+ * @method setFeeAcknowledged(string $yn)
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class RenewAllRequest extends SIP2Request
+{
+    protected $var = [
+        'InstitutionId' => [],
+        'PatronIdentifier' => [],
+        'PatronPassword' => ['default' => ''],
+        'TerminalPassword' => ['default' => ''],
+        'FeeAcknowledged' => ['type' => 'YN', 'default' => 'N'],
+    ];
+
+    public function getMessageString($withSeq = true, $withCrc = true): string
+    {
+        $this->newMessage('65');
+        $this->addVarOption('AO', $this->getVariable('InstitutionId'));
+        $this->addVarOption('AA', $this->getVariable('PatronIdentifier'));
+        $this->addVarOption('AD', $this->getVariable('PatronPassword'), true);
+        $this->addVarOption('AC', $this->getVariable('TerminalPassword'), true);
+        $this->addVarOption('BO', $this->getVariable('FeeAcknowledged'), true);
+
+        return $this->returnMessage($withSeq, $withCrc);
+    }
+}
diff --git a/src/Request/RenewRequest.php b/src/Request/RenewRequest.php
new file mode 100644
index 0000000..ced40ff
--- /dev/null
+++ b/src/Request/RenewRequest.php
@@ -0,0 +1,61 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+/**
+ * RenewRequest is used to renew an item. The ACS should respond with a Renew Response message.
+ * Either or both of the setItemIdentifier and setItemTitle methods must be called for the message to
+ * be useful.
+ *
+ * @method setThirdParty(string $yn)
+ * @method setNoBlock(string $yn)
+ * @method setNBDateDue(string $timestamp)
+ * @method setInstitutionId(string $institutionId)
+ * @method setPatronIdentifier(string $patron)
+ * @method setPatronPassword(string $patronPassword)
+ * @method setItemIdentifier(string $itemIdentifier)
+ * @method setItemTitle(string $itemTitle)
+ * @method setTerminalPassword(string $terminalPassword)
+ * @method setItemProperties(string $itemProperties)
+ * @method setFeeAcknowledged(string $yn)
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class RenewRequest extends SIP2Request
+{
+    protected $var = [
+        'ThirdParty' => ['type' => 'YN', 'default' => 'N'],
+        'NoBlock' => ['type' => 'YN', 'default' => 'N'],
+        'NBDateDue' => ['type' => 'timestamp', 'default' => ''],
+        'InstitutionId' => [],
+        'PatronIdentifier' => [],
+        'PatronPassword' => ['default' => ''],
+        'ItemIdentifier' => ['default' => ''],
+        'ItemTitle' => ['default' => ''],
+        'TerminalPassword' => ['default' => ''],
+        'ItemProperties' => ['default' => ''],
+        'FeeAcknowledged' => ['type' => 'YN', 'default' => 'N'],
+    ];
+
+    public function getMessageString($withSeq = true, $withCrc = true): string
+    {
+        $this->newMessage('29');
+        $this->addFixedOption($this->getVariable('ThirdParty'), 1);
+        $this->addFixedOption($this->getVariable('NoBlock'), 1);
+        $this->addFixedOption($this->datestamp(), 18);
+        $this->addFixedOption($this->getVariable('NBDateDue'), 18);
+
+        $this->addVarOption('AO', $this->getVariable('InstitutionId'));
+        $this->addVarOption('AA', $this->getVariable('PatronIdentifier'));
+        $this->addVarOption('AD', $this->getVariable('PatronPassword'), true);
+        $this->addVarOption('AB', $this->getVariable('ItemIdentifier'), true);
+        $this->addVarOption('AJ', $this->getVariable('ItemTitle'), true);
+        $this->addVarOption('AC', $this->getVariable('TerminalPassword'), true);
+        $this->addVarOption('CH', $this->getVariable('ItemProperties'), true);
+        $this->addVarOption('BO', $this->getVariable('FeeAcknowledged'), true);
+
+        return $this->returnMessage($withSeq, $withCrc);
+    }
+}
diff --git a/src/Request/RequestACSResendRequest.php b/src/Request/RequestACSResendRequest.php
new file mode 100644
index 0000000..17df2dc
--- /dev/null
+++ b/src/Request/RequestACSResendRequest.php
@@ -0,0 +1,22 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+/**
+ * RequestACSResendRequest requests the ACS to re-transmit its last message. It is sent by the SC to the ACS when the
+ * checksum in a received message does not match the value calculated by the SC. The ACS should respond by
+ * re-transmitting its last message, This message should never include a “sequence number” field, even when error
+ * detection is enabled, but would include a “checksum” field since checksums are in use.
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class RequestACSResendRequest extends SIP2Request
+{
+    public function getMessageString($withSeq = true, $withCrc = true): string
+    {
+        $this->newMessage('97');
+        return $this->returnMessage($withSeq, $withCrc);
+    }
+}
diff --git a/src/Request/SCStatusRequest.php b/src/Request/SCStatusRequest.php
new file mode 100644
index 0000000..a4c653a
--- /dev/null
+++ b/src/Request/SCStatusRequest.php
@@ -0,0 +1,37 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+/**
+ * SCStatusRequest message sends SC status to the ACS. It requires an ACS Status Response message reply from the
+ * ACS. This message will be the first message sent by the SC to the ACS once a connection has been established
+ * (exception: the Login Message may be sent first to login to an ACS server program). The ACS will respond with a
+ * message that establishes some of the rules to be followed by the SC and establishes some parameters needed for
+ * further communication.
+ *
+ * @method setStatus(string $status)
+ * @method setWidth(string $width)
+ * @method setVersion(string $version)
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class SCStatusRequest extends SIP2Request
+{
+    protected $var = [
+        'Status' => ['default' => '0'],
+        'Width' => ['default' => '80'],
+        'Version' => ['default' => '2']
+    ];
+
+    public function getMessageString($withSeq = true, $withCrc = true): string
+    {
+        $this->newMessage('99');
+        $this->addFixedOption($this->getVariable('Status'), 1);
+        $this->addFixedOption($this->getVariable('Width'), 3);
+        $this->addFixedOption(sprintf("%03.2f", (float)$this->getVariable('Version')), 4);
+
+        return $this->returnMessage($withSeq, $withCrc);
+    }
+}
diff --git a/src/Request/SIP2Request.php b/src/Request/SIP2Request.php
new file mode 100644
index 0000000..7e1e109
--- /dev/null
+++ b/src/Request/SIP2Request.php
@@ -0,0 +1,146 @@
+<?php
+
+namespace cap60552\SIP2\Request;
+
+use cap60552\SIP2\SIP2Message;
+
+/**
+ * Class SIP2Request extends SIP2Message with methods for building SIP2 message strings
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+abstract class SIP2Request extends SIP2Message
+{
+    // can use these constants for getVariable/setVariable/setDefault etc
+    
+    const CANCEL = 'Cancel';
+    const END = 'End';
+    const EXPIRY_DATE = 'ExpiryDate';
+    const FEE_ACKNOWLEDGED = 'FeeAcknowledged';
+    const FEE_IDENTIFIER = 'FeeIdentifier';
+    const HOLD_TYPE = 'HoldType';
+    const INSTITUTION_ID = 'InstitutionID';
+    const ITEM_IDENTIFIER = 'ItemIdentifier';
+    const ITEM_LOCATION = 'ItemLocation';
+    const ITEM_PROPERTIES = 'ItemProperties';
+    const ITEM_TITLE = 'ItemTitle';
+    const LOCATION = 'Location';
+    const MESSAGE = 'Message';
+    const NB_DATEDUE = 'NBDateDue';
+    const NO_BLOCK = 'NoBlock';
+    const PASSWORD_ALGORITHM = 'PasswordAlgorithm';
+    const PATRON_IDENTIFIER = 'PatronIdentifier';
+    const PATRON_PASSWORD = 'PatronPassword';
+    const PAYMENT_AMOUNT = 'PaymentAmount';
+    const PICKUP_LOCATION = 'PickupLocation';
+    const SIP_LOGIN = 'SIPLogin';
+    const SIP_PASSWORD = 'SIPPassword';
+    const START = 'Start';
+    const STATUS = 'Status';
+    const TERMINAL_PASSWORD = 'TerminalPassword';
+    const THIRD_PARTY = 'ThirdParty';
+    const TRANSACTION_IDENTIFIER = 'TransactionIdentifier';
+    const USERID_ALGORITHM = 'UserIdAlgorithm';
+    const VERSION = 'Version';
+    const WIDTH = 'Width';
+
+    /** @var string request is built up here */
+    private $msgBuild = '';
+
+    /** @var bool tracks when a variable field is used to prevent further fixed fields */
+    private $noFixed = false;
+
+    /**
+     * @var string terminator for requests. This should be just \r (0x0d) according to docs, but some vendors
+     * require \r\n
+     */
+    private $msgTerminator = "\r\n";
+
+    /** @var string variable length field terminator */
+    private $fldTerminator = '|';
+
+
+    private static $seq = -1;
+
+    /**
+     * This class automatically increments a static sequence number, but for testing its useful to have this
+     * start at 0. This method allows it to be reset
+     */
+    public static function resetSequence()
+    {
+        self::$seq = -1;
+    }
+
+    /**
+     * Derived class must implement this to build its SIP2 request
+     */
+    abstract public function getMessageString($withSeq = true, $withCrc = true): string;
+
+
+    /**
+     * Start building a new message
+     * @param string $code
+     */
+    protected function newMessage($code)
+    {
+        /* resets the msgBuild variable to the value of $code, and clears the flag for fixed messages */
+        $this->noFixed = false;
+        $this->msgBuild = $code;
+    }
+
+    protected function addFixedOption($value, $len)
+    {
+        /* adds a fixed length option to the msgBuild IF no variable options have been added. */
+        if ($this->noFixed) {
+            //@codeCoverageIgnoreStart
+            throw new \LogicException('Cannot add fixed options after variable options');
+            //@codeCoverageIgnoreEnd
+        }
+
+        $this->msgBuild .= sprintf("%{$len}s", substr($value, 0, $len));
+        return true;
+    }
+
+    protected function addVarOption($field, $value, $optional = false)
+    {
+        /* adds a variable length option to the message, and also prevents adding additional fixed fields */
+        if ($optional == true && $value == '') {
+            /* skipped */
+            //$this->logger->debug("SIP2: Skipping optional field {$field}");
+        } else {
+            $this->noFixed = true; /* no more fixed for this message */
+            $this->msgBuild .= $field . substr($value, 0, 255) . $this->fldTerminator;
+        }
+        return true;
+    }
+
+    protected function returnMessage($withSeq = true, $withCrc = true): string
+    {
+        /* Finalizes the message and returns it.  Message will remain in msgBuild until newMessage is called */
+        if ($withSeq) {
+            $this->msgBuild .= 'AY' . self::getSeqNumber();
+        }
+        if ($withCrc) {
+            $this->msgBuild .= 'AZ';
+            $this->msgBuild .= self::crc($this->msgBuild);
+        }
+        $this->msgBuild .= $this->msgTerminator;
+
+        return $this->msgBuild;
+    }
+
+    /* Core local utility functions */
+
+    protected static function getSeqNumber()
+    {
+        /* Get a sequence number for the AY field */
+        /* valid numbers range 0-9 */
+        self::$seq++;
+        if (self::$seq > 9) {
+            self::$seq = 0;
+        }
+        return self::$seq;
+    }
+}
diff --git a/src/Response/ACSStatusResponse.php b/src/Response/ACSStatusResponse.php
new file mode 100644
index 0000000..1ca3771
--- /dev/null
+++ b/src/Response/ACSStatusResponse.php
@@ -0,0 +1,72 @@
+<?php
+
+namespace cap60552\SIP2\Response;
+
+/**
+ * Class ACSStatusResponse provides the response from an SCStatus request
+ *
+ * @method getOk()
+ * @method getOnline()
+ * @method getCheckin()
+ * @method getCheckout()
+ * @method getRenewal()
+ * @method getPatronUpdate()
+ * @method getOffline()
+ * @method getTimeout()
+ * @method getRetries()
+ * @method getTransactionDate()
+ * @method getProtocol()
+ * @method getInstitutionId()
+ * @method getLibraryName()
+ * @method getSupportedMessages()
+ * @method getTerminalLocation()
+ * @method getScreenMessage()
+ * @method getPrintLine()
+ * @method getSequenceNumber()
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class ACSStatusResponse extends SIP2Response
+{
+    protected $var = [
+        'Online' => [],
+        'Checkin' => [],
+        'Checkout' => [],
+        'Renewal' => [],
+        'PatronUpdate' => [],
+        'Offline' => [],
+        'Timeout' => [],
+        'Retries' => [],
+        'TransactionDate' => [],
+        'Protocol' => [],
+    ];
+
+    //variable part of the response allowed to contain these...
+    protected $allowedVariables=[
+        self::AO_INSTITUTION_ID,
+        self::AM_LIBRARY_NAME,
+        self::BX_SUPPORTED_MESSAGES,
+        self::AN_TERMINAL_LOCATION,
+        self::AF_SCREEN_MESSAGE,
+        self::AG_PRINT_LINE,
+        self::AY_SEQUENCE_NUMBER
+    ];
+
+    public function __construct($raw)
+    {
+        $this->setVariable('Online', substr($raw, 2, 1));
+        $this->setVariable('Checkin', substr($raw, 3, 1));
+        $this->setVariable('Checkout', substr($raw, 4, 1));
+        $this->setVariable('Renewal', substr($raw, 5, 1));
+        $this->setVariable('PatronUpdate', substr($raw, 6, 1));
+        $this->setVariable('Offline', substr($raw, 7, 1));
+        $this->setVariable('Timeout', substr($raw, 8, 3));
+        $this->setVariable('Retries', substr($raw, 11, 3));
+        $this->setVariable('TransactionDate', substr($raw, 14, 18));
+        $this->setVariable('Protocol', substr($raw, 32, 4));
+
+        $this->parseVariableData($raw, 36);
+    }
+}
diff --git a/src/Response/CheckInResponse.php b/src/Response/CheckInResponse.php
new file mode 100644
index 0000000..845f86b
--- /dev/null
+++ b/src/Response/CheckInResponse.php
@@ -0,0 +1,65 @@
+<?php
+
+namespace cap60552\SIP2\Response;
+
+/**
+ * Class CheckInResponse provides the response from a CheckInRequest
+ *
+ * @method getOk()
+ * @method getResensitize()
+ * @method getMagnetic()
+ * @method getAlert()
+ * @method getTransactionDate()
+ * @method getInstitutionId()
+ * @method getItemIdentifier()
+ * @method getPermanentLocation()
+ * @method getTitleIdentifier()
+ * @method getSortBin()
+ * @method getPatronIdentifier()
+ * @method getMediaType()
+ * @method getItemProperties()
+ * @method getScreenMessage()
+ * @method getPrintLine()
+ * @method getSequenceNumber()
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class CheckInResponse extends SIP2Response
+{
+    //fixed part of response contains these
+    protected $var = [
+        'Ok' => [],
+        'Resensitize' => [],
+        'Magnetic' => [],
+        'Alert' => [],
+        'TransactionDate' => []
+    ];
+
+    //variable part of the response allowed to contain these...
+    protected $allowedVariables=[
+        self::AO_INSTITUTION_ID,
+        self::AB_ITEM_IDENTIFIER,
+        self::AQ_PERMANENT_LOCATION,
+        self::AJ_TITLE_IDENTIFIER,
+        self::CL_SORT_BIN,
+        self::AA_PATRON_IDENTIFIER,
+        self::CK_MEDIA_TYPE,
+        self::CH_ITEM_PROPERTIES,
+        self::AF_SCREEN_MESSAGE,
+        self::AG_PRINT_LINE,
+        self::AY_SEQUENCE_NUMBER
+    ];
+
+    public function __construct($raw)
+    {
+        $this->setVariable('Ok', substr($raw, 2, 1));
+        $this->setVariable('Resensitize', substr($raw, 3, 1));
+        $this->setVariable('Magnetic', substr($raw, 4, 1));
+        $this->setVariable('Alert', substr($raw, 5, 1));
+        $this->setVariable('TransactionDate', substr($raw, 6, 18));
+
+        $this->parseVariableData($raw, 24);
+    }
+}
diff --git a/src/Response/CheckOutResponse.php b/src/Response/CheckOutResponse.php
new file mode 100644
index 0000000..40d5849
--- /dev/null
+++ b/src/Response/CheckOutResponse.php
@@ -0,0 +1,73 @@
+<?php
+
+namespace cap60552\SIP2\Response;
+
+/**
+ * Class CheckoutResponse provides the response from a CheckoutRequest
+ *
+ * @method getOk()
+ * @method getRenewalOk()
+ * @method getMagnetic()
+ * @method getDesensitize()
+ * @method getTransactionDate()
+ * @method getInstitutionId()
+ * @method getPatronIdentifier()
+ * @method getItemIdentifier()
+ * @method getTitleIdentifier()
+ * @method getDueDate()
+ * @method getFeeType()
+ * @method getSecurityInhibit()
+ * @method getFeeAmount()
+ * @method getCurrencyType()
+ * @method getMediaType()
+ * @method getItemProperties()
+ * @method getTransactionId()
+ * @method getScreenMessage()
+ * @method getPrintLine()
+ * @method getSequenceNumber()
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class CheckOutResponse extends SIP2Response
+{
+    //fixed part of response contains these
+    protected $var = [
+        'Ok' => [],
+        'RenewalOk' => [],
+        'Magnetic' => [],
+        'Desensitize' => [],
+        'TransactionDate' => []
+    ];
+
+    //variable part of the response allowed to contain these...
+    protected $allowedVariables=[
+        self::AO_INSTITUTION_ID,
+        self::AA_PATRON_IDENTIFIER,
+        self::AB_ITEM_IDENTIFIER,
+        self::AJ_TITLE_IDENTIFIER,
+        self::AH_DUE_DATE,
+        self::BT_FEE_TYPE,
+        self::CI_SECURITY_INHIBIT,
+        self::BH_CURRENCY_TYPE,
+        self::BV_FEE_AMOUNT,
+        self::CK_MEDIA_TYPE,
+        self::CH_ITEM_PROPERTIES,
+        self::BK_TRANSACTION_ID,
+        self::AF_SCREEN_MESSAGE,
+        self::AG_PRINT_LINE,
+        self::AY_SEQUENCE_NUMBER
+    ];
+
+    public function __construct($raw)
+    {
+        $this->setVariable('Ok', substr($raw, 2, 1));
+        $this->setVariable('RenewalOk', substr($raw, 3, 1));
+        $this->setVariable('Magnetic', substr($raw, 4, 1));
+        $this->setVariable('Desensitize', substr($raw, 5, 1));
+        $this->setVariable('TransactionDate', substr($raw, 6, 18));
+
+        $this->parseVariableData($raw, 24);
+    }
+}
diff --git a/src/Response/EndSessionResponse.php b/src/Response/EndSessionResponse.php
new file mode 100644
index 0000000..b4ed4a8
--- /dev/null
+++ b/src/Response/EndSessionResponse.php
@@ -0,0 +1,43 @@
+<?php
+
+namespace cap60552\SIP2\Response;
+
+/**
+ * Class EndSessionResponse provides the response from a EndSessionRequest
+ *
+ * @method getEndSession()
+ * @method getTransactionDate()
+ * @method getInstitutionId()
+ * @method getPatronIdentifier()
+ * @method getScreenMessage()
+ * @method getPrintLine()
+ * @method getSequenceNumber()
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class EndSessionResponse extends SIP2Response
+{
+    //fixed part of response contains these
+    protected $var = [
+        'EndSession' => [],
+        'TransactionDate' => []
+    ];
+
+    //variable part of the response allowed to contain these...
+    protected $allowedVariables=[
+        self::AO_INSTITUTION_ID,
+        self::AA_PATRON_IDENTIFIER,
+        self::AF_SCREEN_MESSAGE,
+        self::AG_PRINT_LINE,
+        self::AY_SEQUENCE_NUMBER
+    ];
+
+    public function __construct($raw)
+    {
+        $this->setVariable('EndSession', substr($raw, 2, 1));
+        $this->setVariable('TransactionDate', substr($raw, 3, 18));
+        $this->parseVariableData($raw, 21);
+    }
+}
diff --git a/src/Response/FeePaidResponse.php b/src/Response/FeePaidResponse.php
new file mode 100644
index 0000000..b5409dc
--- /dev/null
+++ b/src/Response/FeePaidResponse.php
@@ -0,0 +1,45 @@
+<?php
+
+namespace cap60552\SIP2\Response;
+
+/**
+ * Class FeePaidResponse provides the response from a FeePaidRequest
+ *
+ * @method getPaymentAccepted()
+ * @method getTransactionDate()
+ * @method getInstitutionId()
+ * @method getPatronIdentifier()
+ * @method getTransactionId()
+ * @method getScreenMessage()
+ * @method getPrintLine()
+ * @method getSequenceNumber()
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class FeePaidResponse extends SIP2Response
+{
+    //fixed part of response contains these
+    protected $var = [
+        'PaymentAccepted' => [],
+        'TransactionDate' => []
+    ];
+
+    //variable part of the response allowed to contain these...
+    protected $allowedVariables=[
+        self::AO_INSTITUTION_ID,
+        self::AA_PATRON_IDENTIFIER,
+        self::BK_TRANSACTION_ID,
+        self::AF_SCREEN_MESSAGE,
+        self::AG_PRINT_LINE,
+        self::AY_SEQUENCE_NUMBER
+    ];
+
+    public function __construct($raw)
+    {
+        $this->setVariable('PaymentAccepted', substr($raw, 2, 1));
+        $this->setVariable('TransactionDate', substr($raw, 3, 18));
+        $this->parseVariableData($raw, 21);
+    }
+}
diff --git a/src/Response/HoldResponse.php b/src/Response/HoldResponse.php
new file mode 100644
index 0000000..8544331
--- /dev/null
+++ b/src/Response/HoldResponse.php
@@ -0,0 +1,74 @@
+<?php
+
+namespace cap60552\SIP2\Response;
+
+/**
+ * Class HoldResponse provides the response from a HoldRequest
+ *
+ * @method getOk()
+ * @method getAvailable()
+ * @method getTransactionDate()
+ * @method getExpirationDate()
+ * @method getQueuePosition()
+ * @method getPickupLocation()
+ * @method getInstitutionId()
+ * @method getPatronIdentifier()
+ * @method getItemIdentifier()
+ * @method getTitleIdentifier()
+ * @method getScreenMessage()
+ * @method getPrintLine()
+ * @method getSequenceNumber()
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class HoldResponse extends SIP2Response
+{
+    //fixed part of response contains these
+    protected $var = [
+        'Ok' => [],
+        'Available' => [],
+        'TransactionDate' => []
+    ];
+
+    //variable part of the response allowed to contain these...
+    protected $allowedVariables=[
+        self::BW_EXPIRATION_DATE,
+        self::BR_QUEUE_POSITION,
+        self::BS_PICKUP_LOCATION,
+        self::AO_INSTITUTION_ID,
+        self::AA_PATRON_IDENTIFIER,
+        self::AB_ITEM_IDENTIFIER,
+        self::AJ_TITLE_IDENTIFIER,
+        self::AF_SCREEN_MESSAGE,
+        self::AG_PRINT_LINE,
+        self::AY_SEQUENCE_NUMBER
+    ];
+
+    public function __construct($raw)
+    {
+        /*
+         *   $result = [];
+        $result['fixed'] =
+            [
+                'Ok' => substr($response, 2, 1),
+                'available' => substr($response, 3, 1),
+                'TransactionDate' => substr($response, 4, 18)
+            ];
+
+        //expiration date is optional an indicated by BW
+        $variableOffset = 22;
+        if (substr($response, 22, 2) === 'BW') {
+            $result['fixed']['ExpirationDate'] = substr($response, 24, 18);
+            $variableOffset = 42;
+        }
+
+        $result['variable'] = $this->parseVariableData($response, $variableOffset);
+         */
+        $this->setVariable('Ok', substr($raw, 2, 1));
+        $this->setVariable('Available', substr($raw, 3, 1));
+        $this->setVariable('TransactionDate', substr($raw, 4, 18));
+        $this->parseVariableData($raw, 22);
+    }
+}
diff --git a/src/Response/ItemInformationResponse.php b/src/Response/ItemInformationResponse.php
new file mode 100644
index 0000000..afc54b1
--- /dev/null
+++ b/src/Response/ItemInformationResponse.php
@@ -0,0 +1,72 @@
+<?php
+
+namespace cap60552\SIP2\Response;
+
+/**
+ * Class ItemInformationResponse provides the response from a ItemInformationRequest
+ *
+ * @method getCirculationStatus()
+ * @method getSecurityMarker()
+ * @method getFeeType()
+ * @method getTransactionDate()
+ * @method getHoldQueueLength()
+ * @method getDueDate()
+ * @method getRecallDate()
+ * @method getHoldPickupDate()
+ * @method getItemIdentifier()
+ * @method getTitleIdentifier()
+ * @method getOwner()
+ * @method getCurrencyType()
+ * @method getFeeAmount()
+ * @method getMediaType()
+ * @method getPermanentLocation()
+ * @method getCurrentLocation()
+ * @method getItemProperties()
+ * @method getScreenMessage()
+ * @method getPrintLine()
+ * @method getSequenceNumber()
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class ItemInformationResponse extends SIP2Response
+{
+    //fixed part of response contains these
+    protected $var = [
+        'CirculationStatus' => [],
+        'SecurityMarker' => [],
+        'FeeType' => [],
+        'TransactionDate' => []
+    ];
+
+    //variable part of the response allowed to contain these...
+    protected $allowedVariables=[
+        self::CF_HOLD_QUEUE_LENGTH,
+        self::AH_DUE_DATE,
+        self::CJ_RECALL_DATE,
+        self::CM_HOLD_PICKUP_DATE,
+        self::AB_ITEM_IDENTIFIER,
+        self::AJ_TITLE_IDENTIFIER,
+        self::BG_OWNER,
+        self::BH_CURRENCY_TYPE,
+        self::BV_FEE_AMOUNT,
+        self::CK_MEDIA_TYPE,
+        self::AQ_PERMANENT_LOCATION,
+        self::AP_CURRENT_LOCATION,
+        self::CH_ITEM_PROPERTIES,
+        self::AF_SCREEN_MESSAGE,
+        self::AG_PRINT_LINE,
+        self::AY_SEQUENCE_NUMBER
+    ];
+
+    public function __construct($raw)
+    {
+        $this->setVariable('CirculationStatus', substr($raw, 2, 2));
+        $this->setVariable('SecurityMarker', substr($raw, 4, 2));
+        $this->setVariable('FeeType', substr($raw, 6, 2));
+        $this->setVariable('TransactionDate', substr($raw, 8, 18));
+
+        $this->parseVariableData($raw, 26);
+    }
+}
diff --git a/src/Response/ItemStatusUpdateResponse.php b/src/Response/ItemStatusUpdateResponse.php
new file mode 100644
index 0000000..0e09329
--- /dev/null
+++ b/src/Response/ItemStatusUpdateResponse.php
@@ -0,0 +1,45 @@
+<?php
+
+namespace cap60552\SIP2\Response;
+
+/**
+ * Class ItemStatusUpdateResponse provides the response from a ItemStatusUpdateRequest
+ *
+ * @method getPropertiesOk()
+ * @method getTransactionDate()
+ * @method getItemIdentifier()
+ * @method getTitleIdentifier()
+ * @method getItemProperties()
+ * @method getScreenMessage()
+ * @method getPrintLine()
+ * @method getSequenceNumber()
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class ItemStatusUpdateResponse extends SIP2Response
+{
+    //fixed part of response contains these
+    protected $var = [
+        'PropertiesOk' => [],
+        'TransactionDate' => [],
+    ];
+
+    //variable part of the response allowed to contain these...
+    protected $allowedVariables=[
+        self::AB_ITEM_IDENTIFIER,
+        self::AJ_TITLE_IDENTIFIER,
+        self::CH_ITEM_PROPERTIES,
+        self::AF_SCREEN_MESSAGE,
+        self::AG_PRINT_LINE,
+        self::AY_SEQUENCE_NUMBER
+    ];
+
+    public function __construct($raw)
+    {
+        $this->setVariable('PropertiesOk', substr($raw, 2, 1));
+        $this->setVariable('TransactionDate', substr($raw, 3, 18));
+        $this->parseVariableData($raw, 21);
+    }
+}
diff --git a/src/Response/LoginResponse.php b/src/Response/LoginResponse.php
new file mode 100644
index 0000000..9d9e997
--- /dev/null
+++ b/src/Response/LoginResponse.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace cap60552\SIP2\Response;
+
+/**
+ * Class LoginResponse provides the response from a LoginRequest
+ *
+ * @method getOk()
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class LoginResponse extends SIP2Response
+{
+    protected $var = [
+        'Ok' => ['type' => 'n'],
+    ];
+
+    public function __construct($raw)
+    {
+        $this->setVariable('Ok', substr($raw, 2, 1));
+    }
+}
diff --git a/src/Response/PatronEnableResponse.php b/src/Response/PatronEnableResponse.php
new file mode 100644
index 0000000..6a3aa59
--- /dev/null
+++ b/src/Response/PatronEnableResponse.php
@@ -0,0 +1,53 @@
+<?php
+
+namespace cap60552\SIP2\Response;
+
+/**
+ * Class PatronEnableResponse provides the response from a PatronEnableRequest
+ *
+ * @method getPatronStatus()
+ * @method getLanguage()
+ * @method getTransactionDate()
+ * @method getInstitutionId()
+ * @method getPatronIdentifier()
+ * @method getPersonalName()
+ * @method getValidPatron()
+ * @method getValidPatronPassword()
+ * @method getScreenMessage()
+ * @method getPrintLine()
+ * @method getSequenceNumber()
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class PatronEnableResponse extends SIP2Response
+{
+    //fixed part of response contains these
+    protected $var = [
+        'PatronStatus' => [],
+        'Language' => [],
+        'TransactionDate' => []
+    ];
+
+    //variable part of the response allowed to contain these...
+    protected $allowedVariables=[
+        self::AO_INSTITUTION_ID,
+        self::AA_PATRON_IDENTIFIER,
+        self::AE_PERSONAL_NAME,
+        self::BL_VALID_PATRON,
+        self::CQ_VALID_PATRON_PASSWORD,
+        self::AF_SCREEN_MESSAGE,
+        self::AG_PRINT_LINE,
+        self::AY_SEQUENCE_NUMBER
+    ];
+
+    public function __construct($raw)
+    {
+        $this->setVariable('PatronStatus', substr($raw, 2, 14));
+        $this->setVariable('Language', substr($raw, 16, 3));
+        $this->setVariable('TransactionDate', substr($raw, 19, 18));
+
+        $this->parseVariableData($raw, 37);
+    }
+}
diff --git a/src/Response/PatronInformationResponse.php b/src/Response/PatronInformationResponse.php
new file mode 100644
index 0000000..2174de5
--- /dev/null
+++ b/src/Response/PatronInformationResponse.php
@@ -0,0 +1,100 @@
+<?php
+
+namespace cap60552\SIP2\Response;
+
+/**
+ * Class PatronInformationResponse provides the response from a PatronInformationRequest
+ *
+ * @method getPatronStatus()
+ * @method getLanguage()
+ * @method getTransactionDate()
+ * @method getHoldCount()
+ * @method getOverdueCount()
+ * @method getChargedCount()
+ * @method getFineCount()
+ * @method getRecallCount()
+ * @method getUnavailableCount()
+ * @method getInstitutionId()
+ * @method getPatronIdentifier()
+ * @method getPersonalName()
+ * @method getHoldItemsLimit()
+ * @method getOverdueItemsLimit()
+ * @method getChargedItemsLimit()
+ * @method getValidPatron()
+ * @method getValidPatronPassword()
+ * @method getFeeAmount()
+ * @method getCurrencyType()
+ * @method getFeeLimit()
+ * @method getHoldItems()
+ * @method getOverdueItems()
+ * @method getFineItems()
+ * @method getRecallItems()
+ * @method getUnavailableHoldItems()
+ * @method getHomeAddress()
+ * @method getEmailAddress()
+ * @method getHomePhoneNumber()
+ * @method getScreenMessage()
+ * @method getPrintLine()
+ * @method getSequenceNumber()
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class PatronInformationResponse extends SIP2Response
+{
+    //fixed part of response contains these
+    protected $var = [
+        'PatronStatus' => [],
+        'Language' => [],
+        'TransactionDate' => [],
+        'HoldCount' => [],
+        'OverdueCount' => [],
+        'ChargedCount' => [],
+        'FineCount' => [],
+        'RecallCount' => [],
+        'UnavailableCount' => [],
+    ];
+
+    //variable part of the response allowed to contain these...
+    protected $allowedVariables=[
+        self::AO_INSTITUTION_ID,
+        self::AA_PATRON_IDENTIFIER,
+        self::AE_PERSONAL_NAME,
+        self::BZ_HOLD_ITEMS_LIMIT,
+        self::CA_OVERDUE_ITEMS_LIMIT,
+        self::CB_CHARGED_ITEMS_LIMIT,
+        self::BL_VALID_PATRON,
+        self::CQ_VALID_PATRON_PASSWORD,
+        self::BH_CURRENCY_TYPE,
+        self::BV_FEE_AMOUNT,
+        self::CC_FEE_LIMIT,
+        self::AS_HOLD_ITEMS,
+        self::AT_OVERDUE_ITEMS,
+        self::AU_CHARGED_ITEMS,
+        self::AV_FINE_ITEMS,
+        self::BU_RECALL_ITEMS,
+        self::CD_UNAVAILABLE_HOLD_ITEMS,
+        self::BD_HOME_ADDRESS,
+        self::BE_EMAIL_ADDRESS,
+        self::BF_HOME_PHONE_NUMBER,
+        self::AF_SCREEN_MESSAGE,
+        self::AG_PRINT_LINE,
+        self::AY_SEQUENCE_NUMBER
+    ];
+
+    public function __construct($raw)
+    {
+        $this->setVariable('PatronStatus', substr($raw, 2, 14));
+        $this->setVariable('Language', substr($raw, 16, 3));
+        $this->setVariable('TransactionDate', substr($raw, 19, 18));
+        $this->setVariable('HoldCount', substr($raw, 37, 4));
+        $this->setVariable('OverdueCount', substr($raw, 41, 4));
+        $this->setVariable('ChargedCount', substr($raw, 45, 4));
+        $this->setVariable('FineCount', substr($raw, 49, 4));
+        $this->setVariable('RecallCount', substr($raw, 53, 4));
+        $this->setVariable('UnavailableCount', substr($raw, 57, 4));
+
+        $this->parseVariableData($raw, 61);
+    }
+}
diff --git a/src/Response/PatronStatusResponse.php b/src/Response/PatronStatusResponse.php
new file mode 100644
index 0000000..26e568b
--- /dev/null
+++ b/src/Response/PatronStatusResponse.php
@@ -0,0 +1,57 @@
+<?php
+
+namespace cap60552\SIP2\Response;
+
+/**
+ * Class PatronStatusResponse provides the response from a PatronStatusRequest and a BlockPatronRequest
+ *
+ * @method getPatronStatus()
+ * @method getLanguage()
+ * @method getTransactionDate()
+ * @method getInstitutionId()
+ * @method getPatronIdentifier()
+ * @method getPersonalName()
+ * @method getValidPatron()
+ * @method getValidPatronPassword()
+ * @method getFeeAmount()
+ * @method getCurrencyType()
+ * @method getScreenMessage()
+ * @method getPrintLine()
+ * @method getSequenceNumber()
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class PatronStatusResponse extends SIP2Response
+{
+    //fixed part of response contains these
+    protected $var = [
+        'PatronStatus' => [],
+        'Language' => [],
+        'TransactionDate' => []
+    ];
+
+    //variable part of the response allowed to contain these...
+    protected $allowedVariables=[
+        self::AO_INSTITUTION_ID,
+        self::AA_PATRON_IDENTIFIER,
+        self::AE_PERSONAL_NAME,
+        self::BL_VALID_PATRON,
+        self::CQ_VALID_PATRON_PASSWORD,
+        self::BH_CURRENCY_TYPE,
+        self::BV_FEE_AMOUNT,
+        self::AF_SCREEN_MESSAGE,
+        self::AG_PRINT_LINE,
+        self::AY_SEQUENCE_NUMBER
+    ];
+
+    public function __construct($raw)
+    {
+        $this->setVariable('PatronStatus', substr($raw, 2, 14));
+        $this->setVariable('Language', substr($raw, 16, 3));
+        $this->setVariable('TransactionDate', substr($raw, 19, 18));
+
+        $this->parseVariableData($raw, 37);
+    }
+}
diff --git a/src/Response/RenewAllResponse.php b/src/Response/RenewAllResponse.php
new file mode 100644
index 0000000..bcbce07
--- /dev/null
+++ b/src/Response/RenewAllResponse.php
@@ -0,0 +1,51 @@
+<?php
+
+namespace cap60552\SIP2\Response;
+
+/**
+ * Class RenewAllResponse provides the response from a RenewAllRequest
+ *
+ * @method getOk()
+ * @method getRenewed()
+ * @method getUnrenewed()
+ * @method getTransactionDate()
+ * @method getInstitutionId()
+ * @method getRenewedItems()
+ * @method getUnrenewedItems()
+ * @method getScreenMessage()
+ * @method getPrintLine()
+ * @method getSequenceNumber()
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class RenewAllResponse extends SIP2Response
+{
+    //fixed part of response contains these
+    protected $var = [
+        'Ok' => [],
+        'Renewed' => [],
+        'Unrenewed' => [],
+        'TransactionDate' => []
+    ];
+
+    //variable part of the response allowed to contain these...
+    protected $allowedVariables=[
+        self::AO_INSTITUTION_ID,
+        self::BM_RENEWED_ITEMS,
+        self::BN_UNRENEWED_ITEMS,
+        self::AF_SCREEN_MESSAGE,
+        self::AG_PRINT_LINE,
+        self::AY_SEQUENCE_NUMBER
+    ];
+
+    public function __construct($raw)
+    {
+        $this->setVariable('Ok', substr($raw, 2, 1));
+        $this->setVariable('Renewed', substr($raw, 3, 4));
+        $this->setVariable('Unrenewed', substr($raw, 7, 4));
+        $this->setVariable('TransactionDate', substr($raw, 11, 18));
+        $this->parseVariableData($raw, 29);
+    }
+}
diff --git a/src/Response/RenewResponse.php b/src/Response/RenewResponse.php
new file mode 100644
index 0000000..e517e52
--- /dev/null
+++ b/src/Response/RenewResponse.php
@@ -0,0 +1,73 @@
+<?php
+
+namespace cap60552\SIP2\Response;
+
+/**
+ * Class RenewResponse provides the response from a RenewRequest
+ *
+ * @method getOk()
+ * @method getRenewalOk()
+ * @method getMagnetic()
+ * @method getDesensitize()
+ * @method getTransactionDate()
+ * @method getInstitutionId()
+ * @method getPatronIdentifier()
+ * @method getItemIdentifier()
+ * @method getTitleIdentifier()
+ * @method getDueDate()
+ * @method getFeeType()
+ * @method getSecurityInhibit()
+ * @method getFeeAmount()
+ * @method getCurrencyType()
+ * @method getMediaType()
+ * @method getItemProperties()
+ * @method getTransactionId()
+ * @method getScreenMessage()
+ * @method getPrintLine()
+ * @method getSequenceNumber()
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+class RenewResponse extends SIP2Response
+{
+    //fixed part of response contains these
+    protected $var = [
+        'Ok' => [],
+        'RenewalOk' => [],
+        'Magnetic' => [],
+        'Desensitize' => [],
+        'TransactionDate' => []
+    ];
+
+    //variable part of the response allowed to contain these...
+    protected $allowedVariables=[
+        self::AO_INSTITUTION_ID,
+        self::AA_PATRON_IDENTIFIER,
+        self::AB_ITEM_IDENTIFIER,
+        self::AJ_TITLE_IDENTIFIER,
+        self::AH_DUE_DATE,
+        self::BT_FEE_TYPE,
+        self::CI_SECURITY_INHIBIT,
+        self::BH_CURRENCY_TYPE,
+        self::BV_FEE_AMOUNT,
+        self::CK_MEDIA_TYPE,
+        self::CH_ITEM_PROPERTIES,
+        self::BK_TRANSACTION_ID,
+        self::AF_SCREEN_MESSAGE,
+        self::AG_PRINT_LINE,
+        self::AY_SEQUENCE_NUMBER
+    ];
+
+    public function __construct($raw)
+    {
+        $this->setVariable('Ok', substr($raw, 2, 1));
+        $this->setVariable('RenewalOk', substr($raw, 3, 1));
+        $this->setVariable('Magnetic', substr($raw, 4, 1));
+        $this->setVariable('Desensitize', substr($raw, 5, 1));
+        $this->setVariable('TransactionDate', substr($raw, 6, 18));
+
+        $this->parseVariableData($raw, 24);
+    }
+}
diff --git a/src/Response/SIP2Response.php b/src/Response/SIP2Response.php
new file mode 100644
index 0000000..bc39e05
--- /dev/null
+++ b/src/Response/SIP2Response.php
@@ -0,0 +1,206 @@
+<?php
+
+namespace cap60552\SIP2\Response;
+
+use cap60552\SIP2\Exception\LogicException;
+use cap60552\SIP2\Exception\RuntimeException;
+use cap60552\SIP2\SIP2Message;
+
+/**
+ * Class SIP2Response provides a base class for responses and a factory method for constructing them
+ *
+ * Derived classes declare the variable data they expect to receive, and provide a parser for the 'fixed'
+ * fields
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+abstract class SIP2Response extends SIP2Message
+{
+    const AA_PATRON_IDENTIFIER = 'AA';
+    const AB_ITEM_IDENTIFIER = 'AB';
+    const AE_PERSONAL_NAME = 'AE';
+    const AF_SCREEN_MESSAGE = 'AF';
+    const AG_PRINT_LINE = 'AG';
+    const AH_DUE_DATE = 'AH';
+    const AJ_TITLE_IDENTIFIER = 'AJ';
+    const AM_LIBRARY_NAME='AM';
+    const AN_TERMINAL_LOCATION='AN';
+    const AO_INSTITUTION_ID = 'AO';
+    const AP_CURRENT_LOCATION = 'AP';
+    const AQ_PERMANENT_LOCATION='AQ';
+    const AS_HOLD_ITEMS = 'AS';
+    const AT_OVERDUE_ITEMS = 'AT';
+    const AU_CHARGED_ITEMS = 'AU';
+    const AV_FINE_ITEMS = 'AV';
+    const AY_SEQUENCE_NUMBER = 'AY';
+    const BD_HOME_ADDRESS = 'BD';
+    const BE_EMAIL_ADDRESS = 'BE';
+    const BF_HOME_PHONE_NUMBER = 'BF';
+    const BG_OWNER = 'BG';
+    const BH_CURRENCY_TYPE = 'BH';
+    const BK_TRANSACTION_ID= 'BK';
+    const BL_VALID_PATRON = 'BL';
+    const BM_RENEWED_ITEMS = 'BM';
+    const BN_UNRENEWED_ITEMS = 'BN';
+    const BR_QUEUE_POSITION = 'BR';
+    const BS_PICKUP_LOCATION = 'BS';
+    const BT_FEE_TYPE = 'BT';
+    const BU_RECALL_ITEMS = 'BU';
+    const BV_FEE_AMOUNT = 'BV';
+    const BW_EXPIRATION_DATE = 'BW';
+    const BX_SUPPORTED_MESSAGES='BX';
+    const BZ_HOLD_ITEMS_LIMIT = 'BZ';
+    const CA_OVERDUE_ITEMS_LIMIT = 'CA';
+    const CB_CHARGED_ITEMS_LIMIT = 'CB';
+    const CC_FEE_LIMIT = 'CC';
+    const CD_UNAVAILABLE_HOLD_ITEMS = 'CD';
+    const CF_HOLD_QUEUE_LENGTH = 'CF';
+    const CH_ITEM_PROPERTIES= 'CH';
+    const CI_SECURITY_INHIBIT = 'CI';
+    const CJ_RECALL_DATE = 'CJ';
+    const CK_MEDIA_TYPE= 'CK';
+    const CL_SORT_BIN='CL';
+    const CM_HOLD_PICKUP_DATE = 'CM';
+    const CQ_VALID_PATRON_PASSWORD = 'CQ';
+
+    /** @var array maps SIP2 numeric response codes onto response classes */
+    private static $mapResponseToClass = [
+        '10' => CheckInResponse::class,
+        '12' => CheckOutResponse::class,
+        '16' => HoldResponse::class,
+        '18' => ItemInformationResponse::class,
+        '20' => ItemStatusUpdateResponse::class,
+        '24' => PatronStatusResponse::class,
+        '26' => PatronEnableResponse::class,
+        '30' => RenewResponse::class,
+        '36' => EndSessionResponse::class,
+        '38' => FeePaidResponse::class,
+        '64' => PatronInformationResponse::class,
+        '66' => RenewAllResponse::class,
+        '94' => LoginResponse::class,
+        '98' => ACSStatusResponse::class,
+    ];
+
+    /** @var array maps SIP2 variable code names to a definition */
+    private static $mapCodeToVarDef = [
+        self::AA_PATRON_IDENTIFIER => ['name' => 'PatronIdentifier', 'default'=>''],
+        self::AB_ITEM_IDENTIFIER => ['name' => 'ItemIdentifier', 'default'=>''],
+        self::AE_PERSONAL_NAME => ['name' => 'PersonalName', 'default'=>''],
+        self::AF_SCREEN_MESSAGE => ['name' => 'ScreenMessage', 'type' => 'array', 'default'=>[]],
+        self::AG_PRINT_LINE => ['name' => 'PrintLine', 'type' => 'array', 'default'=>[]],
+        self::AH_DUE_DATE => ['name' => 'DueDate', 'default'=>''],
+        self::AJ_TITLE_IDENTIFIER => ['name' => 'TitleIdentifier', 'default'=>''],
+        self::AM_LIBRARY_NAME => ['name' => 'LibraryName', 'default'=>''],
+        self::AN_TERMINAL_LOCATION => ['name' => 'TerminalLocation', 'default'=>''],
+        self::AO_INSTITUTION_ID => ['name' => 'InstitutionId', 'default'=>''],
+        self::AP_CURRENT_LOCATION => ['name' => 'CurrentLocation', 'default'=>''],
+        self::AQ_PERMANENT_LOCATION => ['name' => 'PermanentLocation', 'default'=>''],
+        self::AS_HOLD_ITEMS => ['name' => 'HoldItems', 'type' => 'array', 'default'=>[]],
+        self::AT_OVERDUE_ITEMS => ['name' => 'OverdueItems', 'type' => 'array', 'default'=>[]],
+        self::AU_CHARGED_ITEMS => ['name' => 'ChargedItems', 'type' => 'array', 'default'=>[]],
+        self::AV_FINE_ITEMS => ['name' => 'FineItems', 'type' => 'array', 'default'=>[]],
+        self::AY_SEQUENCE_NUMBER => ['name' => 'SequenceNumber', 'default'=>''],
+        self::BD_HOME_ADDRESS => ['name' => 'HomeAddress', 'default'=>''],
+        self::BE_EMAIL_ADDRESS => ['name' => 'EmailAddress', 'default'=>''],
+        self::BF_HOME_PHONE_NUMBER => ['name' => 'HomePhoneNumber', 'default'=>''],
+        self::BG_OWNER => ['name' => 'Owner', 'default'=>''],
+        self::BH_CURRENCY_TYPE => ['name' => 'CurrencyType', 'default'=>''],
+        self::BK_TRANSACTION_ID => ['name' => 'TransactionId', 'default'=>''],
+        self::BL_VALID_PATRON => ['name' => 'ValidPatron', 'default'=>''],
+        self::BM_RENEWED_ITEMS => ['name' => 'RenewedItems', 'type' => 'array', 'default'=>[]],
+        self::BN_UNRENEWED_ITEMS => ['name' => 'UnrenewedItems', 'type' => 'array', 'default'=>[]],
+        self::BR_QUEUE_POSITION => ['name' => 'QueuePosition', 'default'=>''],
+        self::BS_PICKUP_LOCATION => ['name' => 'PickupLocation', 'default'=>''],
+        self::BT_FEE_TYPE => ['name' => 'FeeType', 'default'=>''],
+        self::BU_RECALL_ITEMS => ['name' => 'RecallItems', 'type' => 'array', 'default'=>[]],
+        self::BV_FEE_AMOUNT => ['name' => 'FeeAmount', 'default'=>''],
+        self::BW_EXPIRATION_DATE => ['name' => 'ExpirationDate', 'default'=>''],
+        self::BX_SUPPORTED_MESSAGES => ['name' => 'SupportedMessages', 'default'=>''],
+        self::BZ_HOLD_ITEMS_LIMIT => ['name' => 'HoldItemsLimit', 'default'=>''],
+        self::CA_OVERDUE_ITEMS_LIMIT => ['name' => 'OverdueItemsLimit', 'default'=>''],
+        self::CB_CHARGED_ITEMS_LIMIT => ['name' => 'ChargedItemsLimit', 'default'=>''],
+        self::CC_FEE_LIMIT => ['name' => 'FeeLimit', 'default'=>''],
+        self::CD_UNAVAILABLE_HOLD_ITEMS => ['name' => 'UnavailableHoldItems', 'type' => 'array', 'default'=>[]],
+        self::CF_HOLD_QUEUE_LENGTH => ['name' => 'HoldQueueLength', 'default'=>''],
+        self::CH_ITEM_PROPERTIES => ['name' => 'ItemProperties', 'default'=>''],
+        self::CI_SECURITY_INHIBIT => ['name' => 'SecurityInhibit', 'default'=>''],
+        self::CJ_RECALL_DATE => ['name' => 'RecallDate', 'default'=>''],
+        self::CK_MEDIA_TYPE => ['name' => 'MediaType', 'default'=>''],
+        self::CL_SORT_BIN => ['name' => 'SortBin', 'default'=>''],
+        self::CM_HOLD_PICKUP_DATE => ['name' => 'HoldPickupDate', 'default'=>''],
+        self::CQ_VALID_PATRON_PASSWORD => ['name' => 'ValidPatronPassword', 'default'=>'']
+    ];
+
+    protected $allowedVariables = [];
+
+    public static function parse($raw): SIP2Response
+    {
+        if (empty($raw) || !self::checkCRC($raw)) {
+            throw new LogicException("Empty string or bad CRC not expected here");//@codeCoverageIgnore
+        }
+
+        $type = substr($raw, 0, 2);
+        if (!isset(self::$mapResponseToClass[$type])) {
+            throw new RuntimeException("Unexpected SIP2 response $type");
+        }
+
+        //good to go
+        $className = self::$mapResponseToClass[$type];
+        return new $className($raw);
+    }
+
+    public static function checkCRC($raw)
+    {
+        $test = preg_split('/(.{4})$/', trim($raw), 2, PREG_SPLIT_DELIM_CAPTURE);
+        return self::crc($test[0]) == $test[1];
+    }
+
+    protected function parseVariableData($response, $start)
+    {
+        //init allowed variables
+        foreach ($this->allowedVariables as $code) {
+            if (!isset(self::$mapCodeToVarDef[$code])) {
+                throw new LogicException("Unexpected $code in allowed variables"); //@codeCoverageIgnore
+            }
+            $name = self::$mapCodeToVarDef[$code]['name'];
+            if (!$this->hasVariable($name)) {
+                //add a definition for this variable
+                $this->var[$name] = self::$mapCodeToVarDef[$code];
+            }
+        }
+
+        $items = explode("|", substr($response, $start, -7));
+
+        foreach ($items as $item) {
+            $field = substr($item, 0, 2);
+
+            //expected?
+            if (!in_array($field, $this->allowedVariables)) {
+                //we tolerate unexpected values and treat them as array types
+                //named after the code if we don't have a definition for it
+                if (!isset(self::$mapCodeToVarDef[$field])) {
+                    self::$mapCodeToVarDef[$field]=[
+                        'name' => $field,
+                        'type' => 'array'
+                    ];
+                    $name=$field;
+                } else {
+                    $name = self::$mapCodeToVarDef[$field]['name'];
+                }
+                $this->var[$name] = self::$mapCodeToVarDef[$field];
+            }
+
+            $value = substr($item, 2);
+            /* SD returns some odd values on occasion, Unable to locate the purpose in spec, so I strip from
+            * the parsed array. Orig values will remain in ['raw'] element
+            */
+            $clean = trim($value, "\x00..\x1F");
+            if ($clean!='') {
+                $name = self::$mapCodeToVarDef[$field]['name'];
+                $this->addVariable($name, $clean);
+            }
+        }
+    }
+}
diff --git a/src/SIP2Client.php b/src/SIP2Client.php
new file mode 100644
index 0000000..7e6a4de
--- /dev/null
+++ b/src/SIP2Client.php
@@ -0,0 +1,200 @@
+<?php
+
+namespace cap60552\SIP2;
+
+/**
+ * SIP2Client Class
+ *
+ * This class provides a method of communicating with an Integrated
+ * Library System using 3M's SIP2 standard.
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  John Wohlers <john@wohlershome.net>
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+
+use cap60552\SIP2\Exception\RuntimeException;
+use cap60552\SIP2\Request\SIP2Request;
+use cap60552\SIP2\Response\SIP2Response;
+use Psr\Log\LoggerAwareInterface;
+use Psr\Log\LoggerAwareTrait;
+use Psr\Log\LoggerInterface;
+use Psr\Log\NullLogger;
+use Socket\Raw\Factory;
+use Socket\Raw\Socket;
+
+/**
+ * SIP2Client provides a simple client for SIP2 library services
+ *
+ * In the specification, and the comments below, 'SC' (or Self Check) denotes the client, and ACS (or Automated
+ * Circulation System) denotes the server.
+ */
+class SIP2Client implements LoggerAwareInterface
+{
+    use LoggerAwareTrait;
+
+    //-----------------------------------------------------
+    // request options
+    //-----------------------------------------------------
+
+    /**
+     * @var array name=>value request defaults used for every request
+     */
+    private $default=[];
+
+    //-----------------------------------------------------
+    // connection handling
+    //-----------------------------------------------------
+
+    /** @var int maximum number of resends in the event of CRC failure */
+    public $maxretry = 3;
+
+    /** @var Socket */
+    private $socket;
+
+    /** @var Factory injectable factory for creating socket connections */
+    private $socketFactory;
+
+    /**
+     * Constructor allows you to provide a PSR-3 logger, but you can also use the setLogger method
+     * later on.
+     *
+     * @param LoggerInterface|null $logger
+     */
+    public function __construct(LoggerInterface $logger = null)
+    {
+        $this->logger = $logger ?? new NullLogger();
+        $this->setDefault('InstitutionId', 'WohlersSIP');
+    }
+
+    public function setDefault($name, $value)
+    {
+        $this->default[$name] = $value;
+    }
+
+    /**
+     * Allows an alternative socket factory to be injected. The allows us to
+     * mock socket connections for testing
+     *
+     * @param Factory $factory
+     */
+    public function setSocketFactory(Factory $factory)
+    {
+        $this->socketFactory = $factory;
+    }
+
+    /**
+     * Get the current socket factory, creating a default one if necessary
+     * @return Factory
+     */
+    private function getSocketFactory()
+    {
+        if (is_null($this->socketFactory)) {
+            $this->socketFactory = new Factory(); //@codeCoverageIgnore
+        }
+        return $this->socketFactory;
+    }
+
+
+    /**
+     * @param SIP2Request $request
+     * @return SIP2Response
+     * @throws RuntimeException if server fails to produce a valid response
+     */
+    public function sendRequest(SIP2Request $request) : SIP2Response
+    {
+        foreach ($this->default as $name => $value) {
+            $request->setDefault($name, $value);
+        }
+
+        $raw = $this->getRawResponse($request);
+        return SIP2Response::parse($raw);
+    }
+
+    private function getRawResponse(SIP2Request $request, $depth = 0)
+    {
+        $result = '';
+        $terminator = '';
+
+        $message = $request->getMessageString();
+
+        $this->logger->debug('SIP2: Sending SIP2 request '.trim($message));
+        $this->socket->write($message);
+
+        $this->logger->debug('SIP2: Request Sent, Reading response');
+
+        while ($terminator != "\x0D") {
+            //@codeCoverageIgnoreStart
+            try {
+                $terminator = $this->socket->recv(1, 0);
+            } catch (\Exception $e) {
+                break;
+            }
+            //@codeCoverageIgnoreEnd
+
+            $result = $result . $terminator;
+        }
+
+        $this->logger->info("SIP2: result={$result}");
+
+        // test message for CRC validity
+        if (SIP2Response::checkCRC($result)) {
+            $this->logger->debug("SIP2: Message from ACS passed CRC check");
+        } else {
+            //CRC check failed, we resend the request
+            if ($depth < $this->maxretry) {
+                $depth++;
+                $this->logger->warning("SIP2: Message failed CRC check, retry {$depth})");
+                $result = $this->getRawResponse($request, $depth);
+            } else {
+                $errMsg="SIP2: Failed to get valid CRC after {$this->maxretry} retries.";
+                $this->logger->critical($errMsg);
+                throw new RuntimeException($errMsg);
+            }
+        }
+
+        return $result;
+    }
+
+    /**
+     * Connect to ACS via SIP2
+     *
+     * The $bind parameter can be useful where a machine which has multiple outbound connections and its important
+     * to control which one is used (normally because the remote SIP2 service is firewalled to particular IPs
+     *
+     * @param string $address ip:port of remote SIP2 service
+     * @param string|null $bind local ip to bind socket to
+     * @param int $timeout number of seconds to allow for connection to succeed
+     */
+    public function connect($address, $bind = null, $timeout = 15)
+    {
+        $this->logger->debug("SIP2Client: Attempting connection to $address");
+
+        $this->socket = $this->getSocketFactory()->createClient($address, $timeout);
+
+        try {
+            if (!empty($bind)) {
+                $this->logger->debug("SIP2Client: binding socket to $bind");
+                $this->socket->bind($bind);
+            }
+
+            $this->socket->connect($address);
+        } catch (\Exception $e) {
+            $this->socket->close();
+            $this->socket = null;
+            $this->logger->error("SIP2Client: Failed to connect: " . $e->getMessage());
+            throw new RuntimeException("Connection failure", 0, $e);
+        }
+
+        $this->logger->debug("SIP2Client: connected");
+    }
+
+    /**
+     * Disconnect from ACS
+     */
+    public function disconnect()
+    {
+        $this->socket->close();
+        $this->socket = null;
+    }
+}
diff --git a/src/SIP2Message.php b/src/SIP2Message.php
new file mode 100644
index 0000000..574eb7a
--- /dev/null
+++ b/src/SIP2Message.php
@@ -0,0 +1,215 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Exception\LogicException;
+
+/**
+ * SIP2Message Class
+ *
+ * This class provides support for getting/setting request and response variables with some magic methods
+ * as well as SIP2 CRC calculation
+ *
+ * @licence    https://opensource.org/licenses/MIT
+ * @copyright  Paul Dixon <paul@elphin.com>
+ */
+abstract class SIP2Message
+{
+    /**
+     * @var array provides a list of the variables this message can use. Array key is the variable name in
+     * StudlyCaps, value is an array which can contain type, default values
+     */
+    protected $var=[];
+
+    /** @var integer|null current timestamp, useful for testing */
+    protected $timestamp = null;
+
+
+    /**
+     * Calculate SIP2 CRC value
+     * @param string $buf
+     * @return string
+     */
+    protected static function crc(string $buf) : string
+    {
+        $sum = 0;
+
+        $len = strlen($buf);
+        for ($n = 0; $n < $len; $n++) {
+            $sum = $sum + ord(substr($buf, $n, 1));
+        }
+
+        $crc = ($sum & 0xFFFF) * -1;
+
+        /* 2008.03.15 - Fixed a bug that allowed the checksum to be larger then 4 digits */
+        return substr(sprintf("%4X", $crc), -4, 4);
+    }
+
+    /**
+     * Check if class supports given variable
+     * @param string $name
+     * @return bool
+     */
+    public function hasVariable(string $name) : bool
+    {
+        return isset($this->var[$name]);
+    }
+
+    /**
+     * Set default value for a variable - this can be overridden by setVariable
+     *
+     * This method will allow you to attempt to set a default for a variable which the derived class
+     * does not support, in which case it is silently ignored.
+     *
+     * @param string $name
+     * @param string|array $value
+     */
+    public function setDefault(string $name, $value)
+    {
+        if ($this->hasVariable($name)) {
+            $this->var[$name]['default'] = $value;
+        }
+    }
+
+    /**
+     * Get value of specific variable.
+     *
+     * There is also a magic method which instead of getVariable('PatronStatus') would instead allow
+     * getPatronStatus() to be called
+     *
+     * @param string $varName
+     * @return string|array
+     */
+    public function getVariable(string $varName)
+    {
+        $this->ensureVariableExists($varName);
+        return $this->var[$varName]['value'] ??
+            $this->var[$varName]['default'] ??
+            $this->handleMissing($varName);
+    }
+
+    /**
+     * Get name/values of all variables
+     *
+     * This can be useful for building JSON-based results of SIP2 responses
+     * @return array
+     */
+    public function getAll()
+    {
+        $result=[];
+        foreach ($this->var as $name => $data) {
+            $result[$name] = $this->getVariable($name);
+        }
+        return $result;
+    }
+
+    /**
+     * Set variable
+     *
+     * Variables which are defined as timestamps are converted to SIP2 date format automatically
+     *
+     * @param $varName
+     * @param string|array $value
+     */
+    public function setVariable($varName, $value)
+    {
+        $this->ensureVariableExists($varName);
+
+        //check type...
+        $type = $this->var[$varName]['type'] ?? 'string';
+        switch ($type) {
+            case 'timestamp':
+                $value = $this->datestamp($value);
+                break;
+            case 'array':
+                $value = is_array($value) ? $value : [$value];
+                break;
+        }
+
+        $this->var[$varName]['value'] = $value;
+    }
+
+    /**
+     * If $varName is defined as an array, this will append given value. Otherwise value is set as normal
+     * @param string $varName
+     * @param string $value
+     */
+    public function addVariable(string $varName, $value)
+    {
+        $this->ensureVariableExists($varName);
+        $type = $this->var[$varName]['type'] ?? 'string';
+        if (($type === 'array') && isset($this->var[$varName]['value'])) {
+            $this->var[$varName]['value'][] = $value;
+        } else {
+            $this->setVariable($varName, $value);
+        }
+    }
+
+
+    /**
+     * Get current timestamp, which can be override with setTimestamp for testing
+     * @return int
+     */
+    public function getTimestamp()
+    {
+        return $this->timestamp ?? time();
+    }
+
+    /**
+     * Sets current timestamp, which is useful for creating predictable tests
+     * @param $timestamp
+     */
+    public function setTimestamp($timestamp)
+    {
+        $this->timestamp = $timestamp;
+    }
+
+    protected function datestamp($timestamp = '')
+    {
+        /* generate a SIP2 compatible datestamp */
+        /* From the spec:
+        * YYYYMMDDZZZZHHMMSS.
+        * All dates and times are expressed according to the ANSI standard X3.30 for date and X3.43 for time.
+        * The ZZZZ field should contain blanks (code $20) to represent local time. To represent universal time,
+        *  a Z character(code $5A) should be put in the last (right hand) position of the ZZZZ field.
+        * To represent other time zones the appropriate character should be used; a Q character (code $51)
+        * should be put in the last (right hand) position of the ZZZZ field to represent Atlantic Standard Time.
+        * When possible local time is the preferred format.
+        */
+        if ($timestamp != '') {
+            /* Generate a proper date time from the date provided */
+            return date('Ymd    His', $timestamp);
+        } else {
+            /* Current Date/Time */
+            return date('Ymd    His', $this->getTimestamp());
+        }
+    }
+
+    protected function ensureVariableExists($name)
+    {
+        if (!isset($this->var[$name])) {
+            throw new LogicException(get_class($this) . ' has no ' . $name . ' member');
+        }
+    }
+
+    protected function handleMissing($varName)
+    {
+        throw new LogicException(get_class($this) . '::set' . $varName . ' must be called');
+    }
+
+    public function __call($name, $arguments)
+    {
+        if (!preg_match('/^(get|set)(.+)$/', $name, $match)) {
+            throw new LogicException(get_class($this) . ' has no ' . $name . ' method');
+        }
+        $varName = $match[2];
+
+        //get?
+        if ($match[1] === 'get') {
+            return $this->getVariable($varName);
+        }
+        //set
+        $this->setVariable($varName, $arguments[0]);
+        return $this;
+    }
+}
diff --git a/tests/AbstractSIP2ClientTest.php b/tests/AbstractSIP2ClientTest.php
new file mode 100644
index 0000000..4b08369
--- /dev/null
+++ b/tests/AbstractSIP2ClientTest.php
@@ -0,0 +1,138 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\SIP2Request;
+use Prophecy\Argument;
+
+/**
+ * AbstractSIP2ClientTest provides a mock socket which can return a sequence of canned responses, and
+ * helpers to assist with asserting the content of a parsed response
+ */
+abstract class AbstractSIP2ClientTest extends \PHPUnit\Framework\TestCase
+{
+    public function setUp()
+    {
+        SIP2Request::resetSequence();
+    }
+
+    /**
+     * Make a valid response by adding sequence number and CRC
+     * @param $str
+     * @return string
+     */
+    protected function makeResponse($str)
+    {
+        //add sequence number and intro for checksum
+        $str .= 'AY0AZ';
+        //add checksum
+        $str .= $this->crc($str);
+        //add terminator
+        $str .= "\x0D";
+        return $str;
+    }
+
+    /**
+     * Calc SIP2 CRC value
+     * @param $buffer
+     * @return string
+     */
+    private function crc($buffer)
+    {
+        $sum = 0;
+        $len = strlen($buffer);
+        for ($n = 0; $n < $len; $n++) {
+            $sum = $sum + ord($buffer[$n]);
+        }
+        $crc = ($sum & 0xFFFF) * -1;
+        return substr(sprintf("%4X", $crc), -4, 4);
+    }
+
+    /**
+     * This helper creates a socket factory we can pass to the client. The factory returns a mock
+     * socket which will return a sequence of responses after each write() to the socket. This allows
+     * us to easily simulate SIP2 server responses
+     *
+     * @param array $responses
+     * @return \Socket\Raw\Factory
+     */
+    protected function createMockSIP2Server(array $responses)
+    {
+        $socket = $this->prophesize(\Socket\Raw\Socket::class);
+
+        //our mock socket will send each given response in sequence after each write() call
+        $socket->responses = $responses;
+        $socket->responseIdx = -1;
+        $socket->responseOffset = 0;
+        $socket->responseLength = 0;
+
+        $socket->write(Argument::type('string'))->will(function ($args) use ($socket) {
+            //printf("write(%s)\n", $args[0]);
+
+            //next call to recv will start returning our next canned response
+            $socket->responseIdx++;
+            if ($socket->responseIdx >= count($socket->responses)) {
+                throw new \LogicException(
+                    'Mock client has no response for write #' . ($socket->responseIdx + 1) . ':' . $args[0]
+                );
+            }
+            $socket->responseOffset = 0;
+            $socket->responseLength = strlen($socket->responses[$socket->responseIdx]);
+            return true;
+        });
+
+        $socket->recv(1, 0)->will(function ($args) use ($socket) {
+            if ($socket->responseOffset >= $socket->responseLength) {
+                throw new \LogicException('Client is reading past prophesized response');
+            }
+            //return next char of response
+            return $socket->responses[$socket->responseIdx][$socket->responseOffset++];
+        });
+
+        $socket->close()->willReturn(true);
+
+        $socket->connect(Argument::type('string'))->willReturn(true);
+        $socket->bind(Argument::type('string'))->willReturn(true);
+
+        //our factory just returns our mock
+        $factory = $this->prophesize(\Socket\Raw\Factory::class);
+        $factory->createClient(
+            Argument::type('string'),
+            Argument::any()
+        )->willReturn($socket->reveal());
+
+        return $factory->reveal();
+    }
+
+    /**
+     * Checks fixed data in patron info is present and valid
+     * @param string $expected expected value
+     * @param array $info info array returned from parsePatronInfoResponse
+     * @param string $name name of element
+     */
+    protected function assertFixedMetadata($expected, array $info, $name)
+    {
+        $this->assertArrayHasKey($name, $info['fixed']);
+        $this->assertEquals($expected, $info['fixed'][$name]);
+    }
+
+    /**
+     * Checks variable data in patron info is present and valid
+     * @param string|array $expected expected value - for multi-valued responses you can pass an array here
+     * @param array $info info array returned from parsePatronInfoResponse
+     * @param string $name name of element
+     */
+    protected function assertVariableMetadata($expected, array $info, $name)
+    {
+        $this->assertArrayHasKey($name, $info['variable']);
+        if (is_string($expected)) {
+            $expected = [$expected];
+        }
+
+        $valueCount = count($expected);
+        $this->assertCount($valueCount, $info['variable'][$name]);
+        for ($i = 0; $i < $valueCount; $i++) {
+            $this->assertEquals($expected[$i], $info['variable'][$name][$i]);
+        }
+    }
+}
diff --git a/tests/Request/BlockPatronRequestTest.php b/tests/Request/BlockPatronRequestTest.php
new file mode 100644
index 0000000..9b250e8
--- /dev/null
+++ b/tests/Request/BlockPatronRequestTest.php
@@ -0,0 +1,22 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\BlockPatronRequest;
+
+class BlockPatronRequestTest extends AbstractSIP2ClientTest
+{
+    public function testBasic()
+    {
+        $req = new BlockPatronRequest();
+        $req->setTimestamp(strtotime('2018-07-23 09:46:11'));
+
+        $req->setInstitutionId('Banjo');
+        $req->setPatronIdentifier('paul');
+        $req->setMessage('You are blocked');
+
+        $msg = $req->getMessageString();
+
+        $this->assertEquals("01N20180723    094611AOBanjo|ALYou are blocked|AApaul|AC|AY0AZED68\r\n", $msg);
+    }
+}
diff --git a/tests/Request/CheckInRequestTest.php b/tests/Request/CheckInRequestTest.php
new file mode 100644
index 0000000..52115f8
--- /dev/null
+++ b/tests/Request/CheckInRequestTest.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\CheckInRequest;
+
+class CheckInRequestTest extends AbstractSIP2ClientTest
+{
+    public function testBasic()
+    {
+        $req = new CheckInRequest();
+        $req->setTimestamp(strtotime('2018-07-23 09:46:11'));
+
+        $req->setItemIdentifier('1234');
+        $req->setInstitutionId('Banjo');
+        $req->setItemLocation('paul');
+        $req->setItemReturnDate(strtotime('2018-08-01 10:00:00'));
+
+        $msg = $req->getMessageString();
+
+        $this->assertEquals(
+            "09N20180723    09461120180801    100000APpaul|AOBanjo|AB1234|AC|BIN|AY0AZED90\r\n",
+            $msg
+        );
+    }
+}
diff --git a/tests/Request/CheckOutRequestTest.php b/tests/Request/CheckOutRequestTest.php
new file mode 100644
index 0000000..f83f323
--- /dev/null
+++ b/tests/Request/CheckOutRequestTest.php
@@ -0,0 +1,27 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\CheckOutRequest;
+
+class CheckOutRequestTest extends AbstractSIP2ClientTest
+{
+    public function testBasic()
+    {
+        $req = new CheckOutRequest();
+        $req->setTimestamp(strtotime('2018-07-23 09:46:11'));
+
+        $req->setItemIdentifier('1234');
+        $req->setInstitutionId('Banjo');
+        $req->setPatronIdentifier('paul');
+        $req->setPatronPassword('foo');
+
+        $msg = $req->getMessageString();
+
+        $this->assertEquals(
+            "11NN20180723    094611                  ".
+            "AOBanjo|AApaul|AB1234|AC|ADfoo|BON|BIN|AY0AZEAAD\r\n",
+            $msg
+        );
+    }
+}
diff --git a/tests/Request/EndPatronSessionRequestTest.php b/tests/Request/EndPatronSessionRequestTest.php
new file mode 100644
index 0000000..3f3bb73
--- /dev/null
+++ b/tests/Request/EndPatronSessionRequestTest.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\EndPatronSessionRequest;
+
+class EndPatronSessionRequestTest extends AbstractSIP2ClientTest
+{
+    public function testBasic()
+    {
+        $req = new EndPatronSessionRequest();
+        $req->setTimestamp(strtotime('2018-07-23 09:46:11'));
+
+        $req->setInstitutionId('Banjo');
+        $req->setPatronIdentifier('paul');
+
+        $msg = $req->getMessageString();
+
+        $this->assertEquals("3520180723    094611AOBanjo|AApaul|AY0AZF541\r\n", $msg);
+    }
+}
diff --git a/tests/Request/FeePaidRequestTest.php b/tests/Request/FeePaidRequestTest.php
new file mode 100644
index 0000000..77cf42d
--- /dev/null
+++ b/tests/Request/FeePaidRequestTest.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\FeePaidRequest;
+
+class FeePaidRequestTest extends AbstractSIP2ClientTest
+{
+    public function testBasic()
+    {
+        $req = new FeePaidRequest();
+        $req->setTimestamp(strtotime('2018-07-23 09:46:11'));
+
+        $req->setFeeType('01');
+        $req->setPaymentType('02');
+        $req->setPaymentAmount('2.34');
+
+        $req->setInstitutionId('Banjo');
+        $req->setPatronIdentifier('paul');
+        $req->setPatronPassword('foo');
+
+        $msg = $req->getMessageString();
+
+        $this->assertEquals("3720180723    0946110102USDBV2.34|AOBanjo|AApaul|AC|ADfoo|AY0AZEE70\r\n", $msg);
+    }
+}
diff --git a/tests/Request/HoldRequestTest.php b/tests/Request/HoldRequestTest.php
new file mode 100644
index 0000000..7ea4727
--- /dev/null
+++ b/tests/Request/HoldRequestTest.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\HoldRequest;
+
+class HoldRequestTest extends AbstractSIP2ClientTest
+{
+    public function testBasic()
+    {
+        $req = new HoldRequest();
+        $req->setTimestamp(strtotime('2018-07-23 09:46:11'));
+
+        $req->setHoldMode(HoldRequest::MODE_ADD);
+        $req->setItemIdentifier('1234');
+        $req->setInstitutionId('Banjo');
+        $req->setPatronIdentifier('paul');
+        $req->setPatronPassword('foo');
+
+        $msg = $req->getMessageString();
+
+        $this->assertEquals("15+20180723    094611AOBanjo|AApaul|ADfoo|AB1234|BON|AY0AZEFAF\r\n", $msg);
+    }
+}
diff --git a/tests/Request/ItemInformationRequestTest.php b/tests/Request/ItemInformationRequestTest.php
new file mode 100644
index 0000000..4631c8c
--- /dev/null
+++ b/tests/Request/ItemInformationRequestTest.php
@@ -0,0 +1,22 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\ItemInformationRequest;
+
+class ItemInformationRequestTest extends AbstractSIP2ClientTest
+{
+    public function testBasic()
+    {
+        $req = new ItemInformationRequest();
+        $req->setTimestamp(strtotime('2018-07-23 09:46:11'));
+
+        $req->setItemIdentifier('1234');
+        $req->setInstitutionId('Banjo');
+        $req->setTerminalPassword('foo');
+
+        $msg = $req->getMessageString();
+
+        $this->assertEquals("1720180723    094611AOBanjo|AB1234|ACfoo|AY0AZF3E4\r\n", $msg);
+    }
+}
diff --git a/tests/Request/ItemStatusUpdateRequestTest.php b/tests/Request/ItemStatusUpdateRequestTest.php
new file mode 100644
index 0000000..59cdb05
--- /dev/null
+++ b/tests/Request/ItemStatusUpdateRequestTest.php
@@ -0,0 +1,23 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\ItemStatusUpdateRequest;
+
+class ItemStatusUpdateRequestTest extends AbstractSIP2ClientTest
+{
+    public function testBasic()
+    {
+        $req = new ItemStatusUpdateRequest();
+        $req->setTimestamp(strtotime('2018-07-23 09:46:11'));
+
+        $req->setItemIdentifier('1234');
+        $req->setInstitutionId('Banjo');
+        $req->setTerminalPassword('foo');
+        $req->setItemProperties('xyz');
+
+        $msg = $req->getMessageString();
+
+        $this->assertEquals("1920180723    094611AOBanjo|AB1234|ACfoo|CHxyz|AY0AZF170\r\n", $msg);
+    }
+}
diff --git a/tests/Request/LoginRequestTest.php b/tests/Request/LoginRequestTest.php
new file mode 100644
index 0000000..1ce2f7e
--- /dev/null
+++ b/tests/Request/LoginRequestTest.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\LoginRequest;
+
+class LoginRequestTest extends AbstractSIP2ClientTest
+{
+    public function testBasic()
+    {
+        $req = new LoginRequest();
+        $req->setTimestamp(strtotime('2018-07-23 09:46:11'));
+
+        $req->setSIPLogin('alice');
+        $req->setSIPPassword('c4rr0ll');
+
+        $msg = $req->getMessageString();
+
+        $this->assertEquals("9300CNalice|COc4rr0ll|AY0AZF733\r\n", $msg);
+    }
+}
diff --git a/tests/Request/PatronEnableRequestTest.php b/tests/Request/PatronEnableRequestTest.php
new file mode 100644
index 0000000..e729e31
--- /dev/null
+++ b/tests/Request/PatronEnableRequestTest.php
@@ -0,0 +1,23 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\PatronEnableRequest;
+
+class PatronEnableRequestTest extends AbstractSIP2ClientTest
+{
+    public function testBasic()
+    {
+        $req = new PatronEnableRequest();
+        $req->setTimestamp(strtotime('2018-07-23 09:46:11'));
+
+        $req->setInstitutionId('Banjo');
+        $req->setTerminalPassword('bar');
+        $req->setPatronIdentifier('paul');
+        $req->setPatronPassword('foo');
+
+        $msg = $req->getMessageString();
+
+        $this->assertEquals("2520180723    094611AOBanjo|AApaul|ACbar|ADfoo|AY0AZF0C8\r\n", $msg);
+    }
+}
diff --git a/tests/Request/PatronInformationRequestTest.php b/tests/Request/PatronInformationRequestTest.php
new file mode 100644
index 0000000..6ee0195
--- /dev/null
+++ b/tests/Request/PatronInformationRequestTest.php
@@ -0,0 +1,27 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\PatronInformationRequest;
+
+class PatronInformationRequestTest extends AbstractSIP2ClientTest
+{
+    public function testBasic()
+    {
+        $req = new PatronInformationRequest();
+        $req->setTimestamp(strtotime('2018-07-23 09:46:11'));
+
+        $req->setInstitutionId('Banjo');
+        $req->setType('overdue');
+        $req->setInstitutionId('Banjo');
+        $req->setPatronIdentifier('paul');
+        $req->setPatronPassword('foo');
+
+        $msg = $req->getMessageString();
+
+        $this->assertEquals(
+            "6300120180723    094611 Y        AOBanjo|AApaul|AC|ADfoo|BP1|BQ5|AY0AZED6E\r\n",
+            $msg
+        );
+    }
+}
diff --git a/tests/Request/PatronStatusRequestTest.php b/tests/Request/PatronStatusRequestTest.php
new file mode 100644
index 0000000..3f99e4e
--- /dev/null
+++ b/tests/Request/PatronStatusRequestTest.php
@@ -0,0 +1,22 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\PatronStatusRequest;
+
+class PatronStatusRequestTest extends AbstractSIP2ClientTest
+{
+    public function testBasic()
+    {
+        $req = new PatronStatusRequest();
+        $req->setTimestamp(strtotime('2018-07-23 09:46:11'));
+
+        $req->setInstitutionId('Banjo');
+        $req->setPatronIdentifier('paul');
+        $req->setPatronPassword('foo');
+
+        $msg = $req->getMessageString();
+
+        $this->assertEquals("2300120180723    094611AOBanjo|AApaul|AC|ADfoo|AY0AZF16E\r\n", $msg);
+    }
+}
diff --git a/tests/Request/RenewAllRequestTest.php b/tests/Request/RenewAllRequestTest.php
new file mode 100644
index 0000000..b68525f
--- /dev/null
+++ b/tests/Request/RenewAllRequestTest.php
@@ -0,0 +1,22 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\RenewAllRequest;
+
+class RenewAllRequestTest extends AbstractSIP2ClientTest
+{
+    public function testBasic()
+    {
+        $req = new RenewAllRequest();
+        $req->setTimestamp(strtotime('2018-07-23 09:46:11'));
+
+        $req->setInstitutionId('Banjo');
+        $req->setPatronIdentifier('paul');
+        $req->setPatronPassword('foo');
+
+        $msg = $req->getMessageString();
+
+        $this->assertEquals("65AOBanjo|AApaul|ADfoo|BON|AY0AZF4EA\r\n", $msg);
+    }
+}
diff --git a/tests/Request/RenewRequestTest.php b/tests/Request/RenewRequestTest.php
new file mode 100644
index 0000000..d43845f
--- /dev/null
+++ b/tests/Request/RenewRequestTest.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\RenewRequest;
+
+class RenewRequestTest extends AbstractSIP2ClientTest
+{
+    public function testBasic()
+    {
+        $req = new RenewRequest();
+        $req->setTimestamp(strtotime('2018-07-23 09:46:11'));
+
+        $req->setItemIdentifier('1234');
+        $req->setInstitutionId('Banjo');
+        $req->setPatronIdentifier('paul');
+        $req->setPatronPassword('foo');
+
+        $msg = $req->getMessageString();
+
+        $this->assertEquals(
+            "29NN20180723    094611                  AOBanjo|AApaul|ADfoo|AB1234|BON|AY0AZECF9\r\n",
+            $msg
+        );
+    }
+}
diff --git a/tests/Request/RequestACSResendRequestTest.php b/tests/Request/RequestACSResendRequestTest.php
new file mode 100644
index 0000000..4512e72
--- /dev/null
+++ b/tests/Request/RequestACSResendRequestTest.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\RequestACSResendRequest;
+
+class RequestACSResendRequestTest extends AbstractSIP2ClientTest
+{
+    public function testBasic()
+    {
+        $req = new RequestACSResendRequest();
+        $msg = $req->getMessageString();
+        $this->assertEquals("97AY0AZFE2B\r\n", $msg);
+    }
+}
diff --git a/tests/Request/SCStatusRequestTest.php b/tests/Request/SCStatusRequestTest.php
new file mode 100644
index 0000000..4f9f662
--- /dev/null
+++ b/tests/Request/SCStatusRequestTest.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Request\SCStatusRequest;
+
+class SCStatusRequestTest extends AbstractSIP2ClientTest
+{
+    public function testBasic()
+    {
+        $req = new SCStatusRequest();
+        $msg = $req->getMessageString();
+        $this->assertEquals("990 802.00AY0AZFCB1\r\n", $msg);
+    }
+}
diff --git a/tests/Request/SIP2RequestTest.php b/tests/Request/SIP2RequestTest.php
new file mode 100644
index 0000000..fb28401
--- /dev/null
+++ b/tests/Request/SIP2RequestTest.php
@@ -0,0 +1,61 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Exception\LogicException;
+use cap60552\SIP2\Request\LoginRequest;
+
+class SIP2RequestTest extends AbstractSIP2ClientTest
+{
+    /**
+     * verifies the AY field in requests increases and wraps around after 10 requests
+     */
+    public function testSequencing()
+    {
+        for ($s=0; $s<=11; $s++) {
+            $login = new LoginRequest();
+            $login->setSIPLogin('user');
+            $login->setSIPPassword('pass');
+
+            $msg = $login->getMessageString();
+            //9300CNuu|COpp|AY1AZF9E9
+
+            $lastSep=strrpos($msg, '|');
+            $ay=substr($msg, $lastSep+1, 2);
+            $seq=substr($msg, $lastSep+3, 1);
+
+            $this->assertEquals('AY', $ay);
+            $this->assertEquals($s % 10, intval($seq));
+        }
+    }
+
+    /**
+     * Test that getting a variable after setting a default works...
+     */
+    public function testDefault()
+    {
+        $login = new LoginRequest();
+        $login->setDefault('SIPLogin', 'foo');
+        $this->assertEquals('foo', $login->getVariable('SIPLogin'));
+    }
+
+    /**
+     * Test that getting a variable before setting one with no default throws exception
+     * @expectedException LogicException
+     */
+    public function testMissingSet()
+    {
+        $login = new LoginRequest();
+        $login->getVariable('SIPLogin');
+    }
+
+    /**
+     * Test that getting a variable before setting one with no default throws exception
+     * @expectedException LogicException
+     */
+    public function testBadMethodCall()
+    {
+        $login = new LoginRequest();
+        $login->garbageCall();
+    }
+}
diff --git a/tests/Response/ACSStatusResponseTest.php b/tests/Response/ACSStatusResponseTest.php
new file mode 100644
index 0000000..46996e4
--- /dev/null
+++ b/tests/Response/ACSStatusResponseTest.php
@@ -0,0 +1,41 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Response\ACSStatusResponse;
+use cap60552\SIP2\Response\SIP2Response;
+
+class ACSStatusResponseTest extends AbstractSIP2ClientTest
+{
+    public function testResponse()
+    {
+        $raw =  $this->makeResponse("98".
+            "Y".
+            "N".
+            "Y".
+            "N".
+            "Y".
+            "N".
+            "123".
+            "456".
+            "20180711    185645".
+            "2.00".
+            "AOinstitution|");
+
+        /** @var ACSStatusResponse $response */
+        $response = SIP2Response::parse($raw);
+        $this->assertInstanceOf(ACSStatusResponse::class, $response);
+
+        $this->assertEquals('Y', $response->getOnline());
+        $this->assertEquals('N', $response->getCheckin());
+        $this->assertEquals('Y', $response->getCheckout());
+        $this->assertEquals('N', $response->getRenewal());
+        $this->assertEquals('Y', $response->getPatronUpdate());
+        $this->assertEquals('N', $response->getOffline());
+        $this->assertEquals('123', $response->getTimeout());
+        $this->assertEquals('456', $response->getRetries());
+        $this->assertEquals('20180711    185645', $response->getTransactionDate());
+        $this->assertEquals('2.00', $response->getProtocol());
+        $this->assertEquals('institution', $response->getInstitutionId());
+    }
+}
diff --git a/tests/Response/CheckInResponseTest.php b/tests/Response/CheckInResponseTest.php
new file mode 100644
index 0000000..7f2eebe
--- /dev/null
+++ b/tests/Response/CheckInResponseTest.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Response\CheckInResponse;
+use cap60552\SIP2\Response\SIP2Response;
+
+class CheckInResponseTest extends AbstractSIP2ClientTest
+{
+    public function testResponse()
+    {
+        $raw =  $this->makeResponse("10" .
+            "1" .
+            "Y" .
+            "U" .
+            "N" .
+            "20180711    185645" .
+            "AO1234|" .
+            "ABitem|" .
+            "AQloc|" .
+            "AJtitle|" .
+            "CLsort|" .
+            "AApatron|" .
+            "CKmda|" .
+            "CHprop|" .
+            "AFmessage|" .
+            "AGprint|");
+
+        /** @var CheckInResponse $response */
+        $response = SIP2Response::parse($raw);
+        $this->assertInstanceOf(CheckInResponse::class, $response);
+
+        $this->assertEquals('1', $response->getOk());
+        $this->assertEquals('Y', $response->getResensitize());
+        $this->assertEquals('U', $response->getMagnetic());
+        $this->assertEquals('N', $response->getAlert());
+        $this->assertEquals('20180711    185645', $response->getTransactionDate());
+
+        $this->assertEquals('1234', $response->getInstitutionId());
+        $this->assertEquals('patron', $response->getPatronIdentifier());
+        $this->assertEquals('sort', $response->getSortBin());
+        $this->assertEquals('item', $response->getItemIdentifier());
+        $this->assertEquals('title', $response->getTitleIdentifier());
+        $this->assertEquals('loc', $response->getPermanentLocation());
+        $this->assertEquals('mda', $response->getMediaType());
+        $this->assertEquals('prop', $response->getItemProperties());
+    }
+}
diff --git a/tests/Response/CheckOutResponseTest.php b/tests/Response/CheckOutResponseTest.php
new file mode 100644
index 0000000..284079e
--- /dev/null
+++ b/tests/Response/CheckOutResponseTest.php
@@ -0,0 +1,56 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Response\CheckOutResponse;
+use cap60552\SIP2\Response\SIP2Response;
+
+class CheckOutResponseTest extends AbstractSIP2ClientTest
+{
+    public function testResponse()
+    {
+        $raw = $this->makeResponse("12" .
+            "1" .
+            "Y" .
+            "N" .
+            "Y" .
+            "20180711    185645" .
+            "AO1234|" .
+            "AApatron|" .
+            "ABitem|" .
+            "AJtitle|" .
+            "AH20180711    185645|" .
+            "BT01|" .
+            "CIN|" .
+            "BHGBP|" .
+            "BV1.23|" .
+            "CKmda|" .
+            "CHprop|" .
+            "BKxyz|" .
+            "AFmessage|" .
+            "AGprint|");
+
+        /** @var CheckOutResponse $response */
+        $response = SIP2Response::parse($raw);
+        $this->assertInstanceOf(CheckOutResponse::class, $response);
+
+        $this->assertEquals('1', $response->getOk());
+        $this->assertEquals('Y', $response->getRenewalOk());
+        $this->assertEquals('N', $response->getMagnetic());
+        $this->assertEquals('Y', $response->getDesensitize());
+        $this->assertEquals('20180711    185645', $response->getTransactionDate());
+
+        $this->assertEquals('1234', $response->getInstitutionId());
+        $this->assertEquals('patron', $response->getPatronIdentifier());
+        $this->assertEquals('item', $response->getItemIdentifier());
+        $this->assertEquals('title', $response->getTitleIdentifier());
+        $this->assertEquals('20180711    185645', $response->getDueDate());
+        $this->assertEquals('01', $response->getFeeType());
+        $this->assertEquals('N', $response->getSecurityInhibit());
+        $this->assertEquals('GBP', $response->getCurrencyType());
+        $this->assertEquals('1.23', $response->getFeeAmount());
+        $this->assertEquals('mda', $response->getMediaType());
+        $this->assertEquals('prop', $response->getItemProperties());
+        $this->assertEquals('xyz', $response->getTransactionId());
+    }
+}
diff --git a/tests/Response/EndSessionResponseTest.php b/tests/Response/EndSessionResponseTest.php
new file mode 100644
index 0000000..b346f64
--- /dev/null
+++ b/tests/Response/EndSessionResponseTest.php
@@ -0,0 +1,37 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Response\EndSessionResponse;
+use cap60552\SIP2\Response\SIP2Response;
+
+class EndSessionResponseTest extends AbstractSIP2ClientTest
+{
+    public function testResponse()
+    {
+        $raw =  $this->makeResponse("36".
+            "Y".
+            "20180711    185645".
+            "AO1234|".
+            "AApatron|".
+            "AEJoe|".
+            "AFmessage|".
+            "AGprint|");
+
+        /** @var EndSessionResponse $response */
+        $response = SIP2Response::parse($raw);
+        $this->assertInstanceOf(EndSessionResponse::class, $response);
+
+        $this->assertEquals('Y', $response->getEndSession());
+        $this->assertEquals('20180711    185645', $response->getTransactionDate());
+        $this->assertEquals('1234', $response->getInstitutionId());
+        $this->assertEquals('patron', $response->getPatronIdentifier());
+        $this->assertContains('message', $response->getScreenMessage());
+        $this->assertContains('print', $response->getPrintLine());
+
+        //we've thown an AE Personal name in the test response. We wouldn't expect this, but we
+        //tolerate extra data...
+        $this->assertTrue($response->hasVariable('PersonalName'));
+        $this->assertEquals('Joe', $response->getVariable('PersonalName'));
+    }
+}
diff --git a/tests/Response/FeePaidResponseTest.php b/tests/Response/FeePaidResponseTest.php
new file mode 100644
index 0000000..ef04033
--- /dev/null
+++ b/tests/Response/FeePaidResponseTest.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Response\FeePaidResponse;
+use cap60552\SIP2\Response\SIP2Response;
+
+class FeePaidResponseTest extends AbstractSIP2ClientTest
+{
+    public function testResponse()
+    {
+        $raw =  $this->makeResponse("38".
+            "Y".
+            "20180711    185645".
+            "AO1234|".
+            "AApatron|".
+            "BK5555|".
+            "AFmessage|".
+            "AGprint|");
+
+        /** @var FeePaidResponse $response */
+        $response = SIP2Response::parse($raw);
+        $this->assertInstanceOf(FeePaidResponse::class, $response);
+
+        $this->assertEquals('Y', $response->getPaymentAccepted());
+        $this->assertEquals('20180711    185645', $response->getTransactionDate());
+        $this->assertEquals('1234', $response->getInstitutionId());
+        $this->assertEquals('patron', $response->getPatronIdentifier());
+        $this->assertEquals('5555', $response->getTransactionId());
+        $this->assertContains('message', $response->getScreenMessage());
+        $this->assertContains('print', $response->getPrintLine());
+    }
+}
diff --git a/tests/Response/HoldResponseTest.php b/tests/Response/HoldResponseTest.php
new file mode 100644
index 0000000..dc0236f
--- /dev/null
+++ b/tests/Response/HoldResponseTest.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Response\HoldResponse;
+use cap60552\SIP2\Response\SIP2Response;
+
+class HoldResponseTest extends AbstractSIP2ClientTest
+{
+    public function testResponse()
+    {
+        $raw = $this->makeResponse("161Y20180711    185645BW20180711    185645|" .
+            "BR1|BSLibrary|AO123|AApatron|ABitem|AJtitle|AFthankyou|AGprint|");
+
+        /** @var HoldResponse $response */
+        $response = SIP2Response::parse($raw);
+        $this->assertInstanceOf(HoldResponse::class, $response);
+
+        $this->assertEquals('1', $response->getOk());
+        $this->assertEquals('Y', $response->getAvailable());
+        $this->assertEquals('20180711    185645', $response->getTransactionDate());
+        $this->assertEquals('20180711    185645', $response->getExpirationDate());
+
+        $this->assertEquals('1', $response->getQueuePosition());
+        $this->assertEquals('Library', $response->getPickupLocation());
+        $this->assertEquals('123', $response->getInstitutionId());
+        $this->assertEquals('patron', $response->getPatronIdentifier());
+        $this->assertEquals('item', $response->getItemIdentifier());
+        $this->assertEquals('title', $response->getTitleIdentifier());
+        $this->assertContains('thankyou', $response->getScreenMessage());
+        $this->assertContains('print', $response->getPrintLine());
+    }
+}
diff --git a/tests/Response/ItemInformationResponseTest.php b/tests/Response/ItemInformationResponseTest.php
new file mode 100644
index 0000000..cae4306
--- /dev/null
+++ b/tests/Response/ItemInformationResponseTest.php
@@ -0,0 +1,57 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Response\ItemInformationResponse;
+use cap60552\SIP2\Response\SIP2Response;
+
+class ItemInformationResponseTest extends AbstractSIP2ClientTest
+{
+    public function testResponse()
+    {
+        $raw = $this->makeResponse("18" .
+            "01" .
+            "02" .
+            "03" .
+            "20180711    185645" .
+            "CF3|" .
+            "AH20180711    185645|" .
+            "CJ20180711    185646|" .
+            "CM20180711    185647|" .
+            "AB1565921879|" .
+            "AJPerl 5 desktop reference|" .
+            "BGBR1|" .
+            "BHGBP|" .
+            "BV1.23|" .
+            "CK001|" .
+            "AQBR2|" .
+            "APBR3|" .
+            "CHprop|" .
+            "AFmessage|" .
+            "AGprint|");
+
+        /** @var ItemInformationResponse $response */
+        $response = SIP2Response::parse($raw);
+        $this->assertInstanceOf(ItemInformationResponse::class, $response);
+
+        $this->assertEquals('01', $response->getCirculationStatus());
+        $this->assertEquals('02', $response->getSecurityMarker());
+        $this->assertEquals('03', $response->getFeeType());
+        $this->assertEquals('20180711    185645', $response->getTransactionDate());
+        $this->assertEquals('3', $response->getHoldQueueLength());
+        $this->assertEquals('20180711    185645', $response->getDueDate());
+        $this->assertEquals('20180711    185646', $response->getRecallDate());
+        $this->assertEquals('20180711    185647', $response->getHoldPickupDate());
+        $this->assertEquals('1565921879', $response->getItemIdentifier());
+        $this->assertEquals('Perl 5 desktop reference', $response->getTitleIdentifier());
+        $this->assertEquals('BR1', $response->getOwner());
+        $this->assertEquals('GBP', $response->getCurrencyType());
+        $this->assertEquals('1.23', $response->getFeeAmount());
+        $this->assertEquals('001', $response->getMediaType());
+        $this->assertEquals('BR2', $response->getPermanentLocation());
+        $this->assertEquals('BR3', $response->getCurrentLocation());
+        $this->assertEquals('prop', $response->getItemProperties());
+        $this->assertContains('message', $response->getScreenMessage());
+        $this->assertContains('print', $response->getPrintLine());
+    }
+}
diff --git a/tests/Response/ItemStatusUpdateResponseTest.php b/tests/Response/ItemStatusUpdateResponseTest.php
new file mode 100644
index 0000000..4ec0900
--- /dev/null
+++ b/tests/Response/ItemStatusUpdateResponseTest.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Response\ItemStatusUpdateResponse;
+use cap60552\SIP2\Response\SIP2Response;
+
+class ItemStatusUpdateResponseTest extends AbstractSIP2ClientTest
+{
+    public function testResponse()
+    {
+        $raw =$this->makeResponse("20" .
+            "1" .
+            "20180711    185645" .
+            "AB1565921879|" .
+            "AJPerl 5 desktop reference|" .
+            "CHprop|" .
+            "AFmessage|" .
+            "AGprint|");
+
+        /** @var ItemStatusUpdateResponse $response */
+        $response = SIP2Response::parse($raw);
+        $this->assertInstanceOf(ItemStatusUpdateResponse::class, $response);
+
+        $this->assertEquals('1', $response->getPropertiesOk());
+        $this->assertEquals('20180711    185645', $response->getTransactionDate());
+        $this->assertEquals('1565921879', $response->getItemIdentifier());
+        $this->assertEquals('Perl 5 desktop reference', $response->getTitleIdentifier());
+        $this->assertEquals('prop', $response->getItemProperties());
+        $this->assertContains('message', $response->getScreenMessage());
+        $this->assertContains('print', $response->getPrintLine());
+    }
+}
diff --git a/tests/Response/LoginResponseTest.php b/tests/Response/LoginResponseTest.php
new file mode 100644
index 0000000..1465f50
--- /dev/null
+++ b/tests/Response/LoginResponseTest.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Response\LoginResponse;
+use cap60552\SIP2\Response\SIP2Response;
+
+class LoginResponseTest extends AbstractSIP2ClientTest
+{
+    public function testResponse()
+    {
+        $raw =  $this->makeResponse("941");
+
+        /** @var LoginResponse $response */
+        $response = SIP2Response::parse($raw);
+        $this->assertInstanceOf(LoginResponse::class, $response);
+        $this->assertEquals('1', $response->getOk());
+    }
+}
diff --git a/tests/Response/PatronEnableResponseTest.php b/tests/Response/PatronEnableResponseTest.php
new file mode 100644
index 0000000..e9ae7fe
--- /dev/null
+++ b/tests/Response/PatronEnableResponseTest.php
@@ -0,0 +1,39 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Response\PatronEnableResponse;
+use cap60552\SIP2\Response\SIP2Response;
+
+class PatronEnableResponseTest extends AbstractSIP2ClientTest
+{
+    public function testResponse()
+    {
+        $raw =  $this->makeResponse("26" .
+            "XXXXyyyXXXXyyy" .
+            "ENG".
+            "20180711    185645" .
+            "AO1234|" .
+            "AApatron|" .
+            "AEJoe Tester|" .
+            "BLY|".
+            "CQY|".
+            "AFmessage|" .
+            "AGprint|");
+
+        /** @var PatronEnableResponse $response */
+        $response = SIP2Response::parse($raw);
+        $this->assertInstanceOf(PatronEnableResponse::class, $response);
+        $this->assertEquals('XXXXyyyXXXXyyy', $response->getPatronStatus());
+        $this->assertEquals('ENG', $response->getLanguage());
+        $this->assertEquals('20180711    185645', $response->getTransactionDate());
+
+        $this->assertEquals('1234', $response->getInstitutionId());
+        $this->assertEquals('patron', $response->getPatronIdentifier());
+        $this->assertEquals('Joe Tester', $response->getPersonalName());
+
+        $this->assertEquals('Y', $response->getValidPatron());
+        $this->assertEquals('Y', $response->getValidPatronPassword());
+        $this->assertEquals('0', $response->getSequenceNumber());
+    }
+}
diff --git a/tests/Response/PatronInformationResponseTest.php b/tests/Response/PatronInformationResponseTest.php
new file mode 100644
index 0000000..7e18a8f
--- /dev/null
+++ b/tests/Response/PatronInformationResponseTest.php
@@ -0,0 +1,44 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Response\PatronInformationResponse;
+use cap60552\SIP2\Response\SIP2Response;
+
+class PatronInformationResponseTest extends AbstractSIP2ClientTest
+{
+    public function testResponse()
+    {
+        $raw =   $this->makeResponse("64              00020180711    185645000000000010000000000009" .
+            "AOExample City Library|AA1381380|AEMr Joe Tester|BZ9999|CA8888|CB7777|BLY|CQY|BV0.00|" .
+            "AS123|AS456|".
+            "BEjoe.tester@example.com|");
+
+        /** @var PatronInformationResponse $response */
+        $response = SIP2Response::parse($raw);
+        $this->assertInstanceOf(PatronInformationResponse::class, $response);
+        $this->assertEquals('              ', $response->getPatronStatus());
+        $this->assertEquals('000', $response->getLanguage());
+        $this->assertEquals('20180711    185645', $response->getTransactionDate());
+        $this->assertEquals(0, $response->getHoldCount());
+        $this->assertEquals(10, $response->getChargedCount());
+        $this->assertEquals(0, $response->getFineCount());
+        $this->assertEquals(0, $response->getRecallCount());
+        $this->assertEquals(9, $response->getUnavailableCount());
+
+        $this->assertEquals('Example City Library', $response->getInstitutionId());
+        $this->assertEquals('1381380', $response->getPatronIdentifier());
+        $this->assertEquals('Mr Joe Tester', $response->getPersonalName());
+        $this->assertEquals('9999', $response->getHoldItemsLimit());
+        $this->assertEquals('8888', $response->getOverdueItemsLimit());
+        $this->assertEquals('7777', $response->getChargedItemsLimit());
+        $this->assertEquals('Y', $response->getValidPatron());
+        $this->assertEquals('Y', $response->getValidPatronPassword());
+        $this->assertEquals('0.00', $response->getFeeAmount());
+        $this->assertEquals('joe.tester@example.com', $response->getEmailAddress());
+        $this->assertEquals('0', $response->getSequenceNumber());
+
+        $this->assertContains('123', $response->getHoldItems());
+        $this->assertContains('456', $response->getHoldItems());
+    }
+}
diff --git a/tests/Response/PatronStatusResponseTest.php b/tests/Response/PatronStatusResponseTest.php
new file mode 100644
index 0000000..752ce35
--- /dev/null
+++ b/tests/Response/PatronStatusResponseTest.php
@@ -0,0 +1,43 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Response\PatronStatusResponse;
+use cap60552\SIP2\Response\SIP2Response;
+
+class PatronStatusResponseTest extends AbstractSIP2ClientTest
+{
+    public function testResponse()
+    {
+        $raw = $this->makeResponse("24".
+            "xxxYYYYxxxYYYY".
+            "ENG".
+            "20180711    185645".
+            "AO1234|".
+            "AApatron|".
+            "AEJoe|".
+            "BLY|".
+            "CQY|".
+            "BHGBP|".
+            "BV1.23|".
+            "AFmessage|".
+            "AGprint|");
+
+        /** @var PatronStatusResponse $response */
+        $response = SIP2Response::parse($raw);
+        $this->assertInstanceOf(PatronStatusResponse::class, $response);
+        $this->assertEquals('xxxYYYYxxxYYYY', $response->getPatronStatus());
+        $this->assertEquals('ENG', $response->getLanguage());
+        $this->assertEquals('20180711    185645', $response->getTransactionDate());
+
+        $this->assertEquals('1234', $response->getInstitutionId());
+        $this->assertEquals('patron', $response->getPatronIdentifier());
+        $this->assertEquals('Joe', $response->getPersonalName());
+
+        $this->assertEquals('Y', $response->getValidPatron());
+        $this->assertEquals('Y', $response->getValidPatronPassword());
+        $this->assertEquals('1.23', $response->getFeeAmount());
+        $this->assertEquals('GBP', $response->getCurrencyType());
+        $this->assertEquals('0', $response->getSequenceNumber());
+    }
+}
diff --git a/tests/Response/RenewAllResponseTest.php b/tests/Response/RenewAllResponseTest.php
new file mode 100644
index 0000000..9b989ca
--- /dev/null
+++ b/tests/Response/RenewAllResponseTest.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Response\RenewAllResponse;
+use cap60552\SIP2\Response\RenewResponse;
+use cap60552\SIP2\Response\SIP2Response;
+
+class RenewAllResponseTest extends AbstractSIP2ClientTest
+{
+    public function testResponse()
+    {
+        $raw = $this->makeResponse("66" .
+            "1" .
+            "0002".
+            "0003".
+            "20180711    185645" .
+            "AOinstitution|" .
+            "BMbook 1|".
+            "BMbook 2|".
+            "BNbook 3|".
+            "BNbook 4|".
+            "BNbook 5|".
+            "AFmessage|" .
+            "AGprint|");
+
+        /** @var RenewAllResponse $response */
+        $response = SIP2Response::parse($raw);
+        $this->assertInstanceOf(RenewAllResponse::class, $response);
+
+        $this->assertEquals('1', $response->getOk());
+        $this->assertEquals('0002', $response->getRenewed());
+        $this->assertEquals('0003', $response->getUnrenewed());
+        $this->assertEquals('20180711    185645', $response->getTransactionDate());
+
+        $this->assertEquals('institution', $response->getInstitutionId());
+
+
+        $this->assertCount(2, $response->getRenewedItems());
+        $this->assertContains('book 1', $response->getRenewedItems());
+        $this->assertContains('book 2', $response->getRenewedItems());
+
+        $this->assertCount(3, $response->getUnrenewedItems());
+        $this->assertContains('book 3', $response->getUnrenewedItems());
+        $this->assertContains('book 4', $response->getUnrenewedItems());
+        $this->assertContains('book 5', $response->getUnrenewedItems());
+    }
+}
diff --git a/tests/Response/RenewResponseTest.php b/tests/Response/RenewResponseTest.php
new file mode 100644
index 0000000..fac6320
--- /dev/null
+++ b/tests/Response/RenewResponseTest.php
@@ -0,0 +1,56 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Response\RenewResponse;
+use cap60552\SIP2\Response\SIP2Response;
+
+class RenewResponseTest extends AbstractSIP2ClientTest
+{
+    public function testResponse()
+    {
+        $raw = $this->makeResponse("30" .
+            "1" .
+            "Y" .
+            "N" .
+            "Y" .
+            "20180711    185645" .
+            "AO1234|" .
+            "AApatron|" .
+            "ABitem|" .
+            "AJtitle|" .
+            "AH20180711    185645|" .
+            "BT01|" .
+            "CIN|" .
+            "BHGBP|" .
+            "BV1.23|" .
+            "CKmda|" .
+            "CHprop|" .
+            "BKxyz|" .
+            "AFmessage|" .
+            "AGprint|");
+
+        /** @var RenewResponse $response */
+        $response = SIP2Response::parse($raw);
+        $this->assertInstanceOf(RenewResponse::class, $response);
+
+        $this->assertEquals('1', $response->getOk());
+        $this->assertEquals('Y', $response->getRenewalOk());
+        $this->assertEquals('N', $response->getMagnetic());
+        $this->assertEquals('Y', $response->getDesensitize());
+        $this->assertEquals('20180711    185645', $response->getTransactionDate());
+
+        $this->assertEquals('1234', $response->getInstitutionId());
+        $this->assertEquals('patron', $response->getPatronIdentifier());
+        $this->assertEquals('item', $response->getItemIdentifier());
+        $this->assertEquals('title', $response->getTitleIdentifier());
+        $this->assertEquals('20180711    185645', $response->getDueDate());
+        $this->assertEquals('01', $response->getFeeType());
+        $this->assertEquals('N', $response->getSecurityInhibit());
+        $this->assertEquals('GBP', $response->getCurrencyType());
+        $this->assertEquals('1.23', $response->getFeeAmount());
+        $this->assertEquals('mda', $response->getMediaType());
+        $this->assertEquals('prop', $response->getItemProperties());
+        $this->assertEquals('xyz', $response->getTransactionId());
+    }
+}
diff --git a/tests/Response/SIP2ResponseTest.php b/tests/Response/SIP2ResponseTest.php
new file mode 100644
index 0000000..575f79b
--- /dev/null
+++ b/tests/Response/SIP2ResponseTest.php
@@ -0,0 +1,87 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Exception\LogicException;
+use cap60552\SIP2\Exception\RuntimeException;
+use cap60552\SIP2\Response\EndSessionResponse;
+use cap60552\SIP2\Response\LoginResponse;
+use cap60552\SIP2\Response\SIP2Response;
+
+class SIP2ResponseTest extends AbstractSIP2ClientTest
+{
+    /**
+     * Test that a SIP2 service providing a response code we don't know will throw an exception
+     *
+     * @expectedException RuntimeException
+     */
+    public function testResponse()
+    {
+        $raw =  $this->makeResponse("771");
+        SIP2Response::parse($raw);
+    }
+
+    /**
+     * Test that a response with new codes in it is handled
+     *
+     */
+    public function testUnknownVariableCodes()
+    {
+        $raw =  $this->makeResponse("36".
+            "Y".
+            "20180711    185645".
+            "AJ1234|".
+            "ZZtop|");
+
+        /** @var EndSessionResponse $response */
+        $response = SIP2Response::parse($raw);
+        $this->assertInstanceOf(EndSessionResponse::class, $response);
+        $this->assertEquals('Y', $response->getEndSession());
+
+        $this->assertTrue($response->hasVariable('TitleIdentifier'));
+        $this->assertTrue($response->hasVariable('ZZ'));
+    }
+
+    public function testGetAll()
+    {
+        $raw =  $this->makeResponse("36".
+            "Y".
+            "20180711    185645".
+            "AOlibrary|".
+            "AGline1|".
+            "AGline2|");
+
+        /** @var EndSessionResponse $response */
+        $response = SIP2Response::parse($raw);
+        $this->assertInstanceOf(EndSessionResponse::class, $response);
+
+        $data = $response->getAll();
+        $this->assertCount(7, $data);
+        $this->assertArrayHasKey('EndSession', $data);
+        $this->assertEquals('Y', $data['EndSession']);
+
+        $this->assertArrayHasKey('PrintLine', $data);
+        $this->assertCount(2, $data['PrintLine']);
+        $this->assertEquals('line1', $data['PrintLine'][0]);
+    }
+
+    /**
+     * Test that attempting to get unexpected data on a response will throw exception
+     *
+     * @expectedException LogicException
+     */
+    public function testGetInvalidVar()
+    {
+        $raw =  $this->makeResponse("36".
+            "Y".
+            "20180711    185645".
+            "AOlibrary|".
+            "AGline1|".
+            "AGline2|");
+
+        /** @var EndSessionResponse $response */
+        $response = SIP2Response::parse($raw);
+
+        $response->getVariable('TitleIdentifier');
+    }
+}
diff --git a/tests/SIP2ClientTest.php b/tests/SIP2ClientTest.php
new file mode 100644
index 0000000..f076a2f
--- /dev/null
+++ b/tests/SIP2ClientTest.php
@@ -0,0 +1,171 @@
+<?php
+
+namespace cap60552\SIP2;
+
+use cap60552\SIP2\Exception\RuntimeException;
+use cap60552\SIP2\Request\LoginRequest;
+use cap60552\SIP2\Response\LoginResponse;
+use Prophecy\Argument;
+
+/**
+ * SIP2ClientTest tests the connection capabilities of the client by mocking a socket pretending to be a SIP2 server
+ */
+class SIP2ClientTest extends AbstractSIP2ClientTest
+{
+    /**
+     * Basic test of typical client/server interaction
+     */
+    public function testLogin()
+    {
+        //our mock socket will return these responses in sequence after each write() to the socket
+        //here we simulate a login response
+        $responses = [
+            $this->makeResponse("941")
+        ];
+
+        $client = new SIP2Client;
+        $client->setSocketFactory($this->createMockSIP2Server($responses));
+
+        $client->connect('10.0.0.0');
+
+        $loginRequest = new LoginRequest();
+        $loginRequest->setSIPLogin('username');
+        $loginRequest->setSIPPassword('password');
+
+        /** @var LoginResponse $response */
+        $response = $client->sendRequest($loginRequest);
+        $this->assertInstanceOf(LoginResponse::class, $response);
+
+        $this->assertEquals('1', $response->getOk());
+
+        $client->disconnect();
+    }
+
+    /**
+     * Test that client will retry a request with bad CRC
+     */
+    public function testCRCFailureRetry()
+    {
+        //our mock socket will return these responses in sequence after each write() to the socket
+        //here we simulate a login response with a bad CRC, followed by a good one
+        $responses = [
+            "940AY0AZ1234\r",
+            $this->makeResponse("941")
+        ];
+
+        $client = new SIP2Client;
+        $client->setSocketFactory($this->createMockSIP2Server($responses));
+
+        $client->connect('10.0.0.0');
+
+        $loginRequest = new LoginRequest();
+        $loginRequest->setSIPLogin('username');
+        $loginRequest->setSIPPassword('password');
+
+        /** @var LoginResponse $response */
+        $response = $client->sendRequest($loginRequest);
+        $this->assertInstanceOf(LoginResponse::class, $response);
+        $this->assertEquals('1', $response->getOk());
+    }
+
+    /**
+     * Test that repeated failure of a SIP2 server to provide a valid CRC produces an exception
+     *
+     * @expectedException RuntimeException
+     */
+    public function testCRCFailureAbort()
+    {
+        //our mock socket will return these responses in sequence after each write() to the socket
+        //here we simulate a continued failure to provide a valid response, leading us to abort after
+        //3 retries
+        $responses = [
+            "940AY0AZ1234\r",
+            "940AY0AZ1234\r",
+            "940AY0AZ1234\r",
+            "940AY0AZ1234\r",
+        ];
+
+        $client = new SIP2Client;
+        $client->setSocketFactory($this->createMockSIP2Server($responses));
+
+        $client->connect('10.0.0.0');
+
+        $loginRequest = new LoginRequest();
+        $loginRequest->setSIPLogin('username');
+        $loginRequest->setSIPPassword('password');
+
+        /** @var LoginResponse $response */
+        $client->sendRequest($loginRequest); //exception should be thrown
+    }
+
+    /**
+     * THis just verifies that Socket::bind is called if we've asked for a specific binding
+     */
+    public function testBinding()
+    {
+        $client = new SIP2Client;
+        $client->setSocketFactory($this->createBindingTestMockSIP2Server());
+
+        $client->connect('10.0.0.0', '192.168.1.1');
+
+        //we don't really need an assertion, as its enough to reach here without exception
+        //and the mock includes a prediction for a call on bind...
+    }
+
+    /**
+     * Test that failure to connect throws exception
+     *
+     * @expectedException RuntimeException
+     */
+    public function testConnectionFailure()
+    {
+        $client = new SIP2Client;
+        $client->setSocketFactory($this->createUnconnectableMockSIP2Server());
+        $client->connect('10.0.0.0');
+    }
+
+    /**
+     * This provides a socket factory which will always fail to connect
+     * @return \Socket\Raw\Factory
+     */
+    protected function createUnconnectableMockSIP2Server()
+    {
+        $socket = $this->prophesize(\Socket\Raw\Socket::class);
+        $socket->connect(Argument::type('string'))->will(function () {
+            throw new \Exception('Test connection failure');
+        });
+
+        $socket->close()->willReturn(true);
+
+        //our factory will always fail to connect...
+        $factory = $this->prophesize(\Socket\Raw\Factory::class);
+        $factory->createClient(
+            Argument::type('string'),
+            Argument::any()
+        )->willReturn($socket->reveal());
+
+        return $factory->reveal();
+    }
+
+    /**
+     * This provides a socket factory which will verify the bind method is  called
+     * @return \Socket\Raw\Factory
+     */
+    private function createBindingTestMockSIP2Server()
+    {
+        $socket = $this->prophesize(\Socket\Raw\Socket::class);
+        $socket->connect(Argument::type('string'))->willReturn(true);
+
+        //we verify bind gets called...
+        $socket->bind(Argument::type('string'))->shouldBeCalled()->willReturn(true);
+
+        //our factory will always fail to connect...
+        $factory = $this->prophesize(\Socket\Raw\Factory::class);
+        $factory->createClient(
+            Argument::type('string'),
+            Argument::any()
+        )->willReturn($socket->reveal());
+
+        return $factory->reveal();
+    }
+}