WebSocket support

Moclojer now supports WebSockets, allowing real-time bidirectional communication

It is possible to configure WebSocket endpoints for real-time bidirectional communication:

# WebSocket echo server
- websocket:
    path: /ws/echo
    on-connect:
      # Message sent when client connects
      response: '{"status": "connected", "message": "Welcome to WebSocket Echo!"}'
    on-message:
      # Simple echo for "ping" message
      - pattern: "ping"
        response: "pong"
      # Echo any JSON content with "echo" field
      - pattern: '{"echo": "{{json-params.echo}}"}'
        response: '{"echoed": "{{json-params.echo}}"}'

When receiving a connection at the /ws/echo endpoint, Moclojer will respond with {"status": "connected", "message": "Welcome to WebSocket Echo!"}.

When the client sends the message ping, the server will respond with pong.

If the client sends a JSON with the echo field, such as {"echo": "hello world"}, the server will respond with {"echoed": "hello world"}.

WebSocket Properties

• path: The URL path for the WebSocket endpoint

• on-connect: Configuration for the client connection event

  • response: Message sent to the client when it connects

• on-message: List of message patterns and their respective responses

  • pattern: Message pattern to be matched

  • response: Response to be sent when the pattern is found

Using templates in responses

Just like HTTP endpoints, you can use templates in WebSocket responses:

- websocket:
    path: /ws/user/:username
    on-connect:
      response: '{"status": "connected", "message": "Welcome, {{path-params.username}}!"}'
    on-message:
      - pattern: '{"action": "get-profile"}'
        response: '{"user": "{{path-params.username}}", "profile": {"joined": "2025-03-20"}}'

You can access parameters from different sources:

• path-params: URL path parameters (like :username in the example above)

• query-params: URL query parameters

• json-params: Fields in received JSON messages

Testing WebSocket connections

You can test WebSocket connections using tools like websocat or wscat:

# Using websocat
websocat "ws://localhost:8000/ws/echo" --text

# Using wscat
wscat -c ws://localhost:8000/ws/echo

Example interaction:

Connected to ws://localhost:8000/ws/echo
< {"status": "connected", "message": "Welcome to WebSocket Echo!"}
> ping
< pong
> {"echo": "hello world"}
< {"echoed": "hello world"}

WebSocket support in Moclojer significantly simplifies the development and testing of applications that use real-time communication.

Swagger:

WebSocket Echo Server

GET /ws/echo

WebSocket endpoint that responds to "ping" messages with "pong" and echoes JSON messages.

101: Switching Protocols WebSocket connection established

{
  "status": "connected",
  "message": "Welcome to WebSocket Echo!"
}