How to upgrade an HTTPConnection to a WebsocketConnection in Jetty 9?

Question

I've been reading the documentation of Jetty 9 and they seemed to have gotten rid of the Jetty Socket Connector. So now we have a general ServerConnector and we "upgrade" and HTTPConnection to a WebSocket connection. I've read the documentation about Socket vs WebSocket ( Difference between socket and websocket? ) and everything linked in that answer. My question is:

1) How do I do the upgrade from HTTPConnection to WebSocket connection? Could someone provide some sample code please?

2) I'm building a desktop app that connects to the server I am writing as well. I need to simulate a TCP connection, will the WebSocketConnection work for me? I ask this because I mostly hear about WebSockets in the context of Browsers and I want to make sure that it is something that I can use in my client app.

Thank you!

Answer 1

Answer for Q1)

I think for your first question this will help. Please refer to the given link for more details. Jetty provides the ability to wire up WebSocket endpoints to Servlet Path Specs via the use of a WebSocketServlet bridge servlet. Internally, Jetty manages the HTTP Upgrade to WebSocket and migration from a HTTP Connection to a WebSocket Connection.

Link1: http://www.eclipse.org/jetty/documentation/current/jetty-websocket-server-api.html

Answer for Q2)

The full duplex communication of websocket server and client happens with the initial TCP handshake. For your websocket client app the following working example can be surely used... It is aa pure JAVA WEBSOCKET CLIENT. I tried it and it works well.

Link2: http://www.eclipse.org/jetty/documentation/current/jetty-websocket-client-api.html

Answer 2

WebSocket is not a naked TCP connection, lets get that out of the way first.

It is a framing protocol, for TEXT, BINARY, and CONTROL frames (Control frames are tiny frames for things like PING, PONG, CLOSE)

It would be best to read the official protocol spec to better understand this: RFC-6455

There is no requirement for the client to be a browser, the client can be any application capable of making a web request.

If this fits your need, then read on.

Jetty itself provides a WebSocket server and WebSocket client implementation using a native API and also supporting the javax.websocket standard (aka JSR-356).

As for the Jetty WebSocket Server, it internally performs the upgrade within the org.eclipse.jetty.websocket.server.WebSocketFactory upgrade() private method.

If you choose to experiment with WebSocket on Jetty, read the documentation and choose from either the native API or javax.websocket API, either one will work.

If you want to understand the difference in those APIs, there's actually a different question/answer for that .