WebSocket Server API

A WebSocket API can be very useful for real-time connection applications and chat apps. More recently, with the giant flow of apps using LLM tools, it has become unviable to use classical HTTP APIs to run those LLM services. With that said, this code serves as a basis for developers to create their own intelligent service provider.

How to use

1. Install the dependencies

npm install

2. Run the server

npm start

run from the root directory

3. Connect to the server

const ws = new WebSocket("ws://localhost:8080");

when in production, use the servers address

(extra) 4. Want to run in the client?

I created a simple client that connects to the server and sends different types of messages. The client was built using Next js and has a simple UI that allows you to send messages to the server. Check the repo link below.

WebSocket Client

General structure

sequenceDiagram
    participant Client
    participant HTTPServer
    participant WebSocketServer
    participant RequestHandlerManager
    participant MessageHandlerFactory
    participant MessageHandler

    Client->>HTTPServer: GET /get-token?username=user1
    HTTPServer-->>Client: 200 OK { token: "JWT" }

    Client->>WebSocketServer: WebSocket Connection with JWT
    WebSocketServer->>WebSocketServer: Verify JWT
    WebSocketServer-->>Client: Connection Established

    WebSocketServer->>RequestHandlerManager: Instantiate RequestHandlerManager(ws)
    RequestHandlerManager->>WebSocketServer: Add Event Listeners

    Client->>RequestHandlerManager: Send Message
    RequestHandlerManager->>RequestHandlerManager: handleMessage(event.data)
    RequestHandlerManager->>MessageHandlerFactory: createHandler(jsonReq.type, ws)
    MessageHandlerFactory->>MessageHandler: Instantiate Appropriate Handler
    MessageHandlerFactory-->>RequestHandlerManager: Return Handler

    RequestHandlerManager->>MessageHandler: handler.handle(jsonReq)
    MessageHandler->>Client: Send Response

Loading

You can modify the RequestHandler class to handle the messages as you wish. Or even turn that into a factory to instantiate different handlers for different types of clients. The idea is that the handlers are responsible for the business logic of the application. They can process the messages, send messages to other clients, or even trigger events in other services like LLMs.

Next steps

• Implement a more robust JWT verification
• Implement a more robust message handling system (maybe switching from WebSocket to Socket.io can make it easier)
• Implement an SDK that holds defined types of messages that could be shared between the client and the server

Observations

• This code is a simple example of a WebSocket server. It is not production-ready. For more robuts systems, consider using routing libraries that can help you create different sockets for different types of messages.
• This code is not a full implementation of a JWT verification system. It is just a simple example of how you can use JWT to authenticate your clients. The client and the server need to share a key to generate and verify the JWT.
• This code is not a full implementation of a message handling system. It is just a simple example of how you can use a factory to instantiate different handlers for different types of messages. You can create a more robust system that can handle different types of messages and different types of clients.