Question

In the new Jetty Versions, the WebSocket implementation was divided into several subinterfaces:

http://download.eclipse.org/jetty/stable-7/apidocs/org/eclipse/jetty/websocket/WebSocket.html

Why was it a good idea to do that?
And what are good use-cases for this separation?

Answer 1

Ok, now that I read more about this issue and implemented something I’ll try to answer it myself.

The standard WebSocket Interface has only the methods

onOpen(Connection con)

and

onClose(int closeCode, String message)

with the Connection you acquire when a WebSocket is opened you can send messages to the Browser (binary, or text).

So the standard WebSocket Interface is basically just for opening a connection and sending messages to the browser.

You don’t have to deal there with the other functions, e.g. when messages arrive from the Browser.

If you want additional functionality there are the other Subinterfaces of WebSocket: Websocket.OnFrame, OnBinaryMessage, OnTextMessage, OnControl

So now if you want for your WebSocket to handle text messages and binary messages you have to implement it like this:

class MyWebSocket implements  WebSocket.OnTextMessage, WebSocket.OnBinaryMessage{
    // Implementation
}

You always only need to implement the interfaces that you need for your task and not all the other functions if they are irrelevant to you. This simplifies the code and reduces code length.