Whitepaper

Ubahn is a framework for creating chatbot dialogs. Key aspects of Ubahn:

• Developers define a conversation structure in a YAML file.
• Each conversation consists of named inputs and outputs.
• The logic and appearance of inputs and outputs is defined by external applications which use Ubahn.
• The framework doesn’t do any NLP or AI, it doesn’t assume which channel is used for communication. It’s purely about creating a structure of a conversation and building specific implementations on top of that structure.
• Named after Munich subway system of the same name.

Here’s an example of a conversation:

version: 1

sequence:
  - welcome
  - weather-report

triggers:
  - i-user-welcome

fallback: clarification

outputs:
  welcome:
    expectedInputs:
      i-yes: next
      i-no: bye
    fallback: welcome-clarification

• version: 1 defines Ubahn protocol version number. It’s useful if we introduce breaking changes to the format of conversation file.
• sequence outlines the structure we want to have in the conversation. It should have a list of named agent outputs, in order of their appearance. Even though the structure is linear, Ubahn supports conditional jumps.
• triggers is a list of named inputs that trigger conversation start.
• fallback defines the global fallback output which is called when Ubahn doesn’t know which output to call.
• outputs defines named agent outputs. Each output may have a dedicated fallback and may expect many inputs. For example in this case:

i-yes: next
i-no: bye

we say that if user input was i-yes, the conversation goes to the next element (weather-report), if the input was i-no, the conversation goes to the bye output.

You may wonder, where do we have those weather-report, bye, i-yes etc.? All of them are just names. You should use Ubahn API to map those names to specific entities with business logic. For example weather-report output may be a rich UI, or a picture—whatever. bye maybe a smile, or a text. i-yes is how your implementation interprets Yes answer, and btw you don’t have to name it i-yes, this is just an example.

Here’s how the above conversation may look like in real life: