Does Jetty support websocket proxying?

[Spandana806]

11.0.17

Question Does Jetty support websocket proxying? I want my application to be able to proxy http requests and websocket requests via Jetty server.

Using ProxyServlet.Transparent, I am able to redirect my http requests to target server and get responses. How do we achieve the same redirection for websocket subscriptions?

The below implementation works:

Code snippet:

public class MyProxy extends ProxyServlet.Transparent
{

    @Override
    public void init(ServletConfig config) throws ServletException 
   {
        myServletConfig = buildMyServletConfig(config);
        super.init(myServletConfig);
    }
   @Override
    protected String rewriteTarget(HttpServletRequest request) 
   {        
        myServletConfig.setProxyTo("http://targetServer/endpoint");
        super.init(myServletConfig);
        return super.rewriteTarget(request);     
    }
}

How do we achieve the reverse proxying for websocket subscriptions?

[sbordet]

WebSocket proxying is possible, but not implemented -- this is one of the first times we get asked about this.

We have implemented it as a proof-of-concept (not production ready code) in a test case here: https://github.com/jetty/jetty.project/blob/jetty-10.0.18/jetty-websocket/websocket-jetty-tests/src/test/java/org/eclipse/jetty/websocket/tests/proxy/WebSocketProxy.java

If you want to write your own you can start from there.

Alternatively, you may establish a commercial support from Webtide, and we will write the code for you and for the whole community -- a great way to give back.

[Spandana806]

Hi Simone, Thank you for the prompt response. As per the document, there are two ways of implementing websockets, I have tried the first way of using standard javax.websocket API. I have added a websocket server which opens a new client session to my target server and thus acting as a proxy between actual client and the target server.

Below is the pictorial representation of how I achieved websocket proxying using javax APIs:

Please confirm if it is the right way to achieve websocket proxying.

I will be trying your suggestion which uses Jetty-specific WebSocket APIs. Is there any difference in terms of performance or in any other way, between the standard javax APIs and the jetty specific APIs?

[sbordet]

I recommend you do it with the Jetty 12 WebSocket APIs because they have better support for backpressure: https://eclipse.dev/jetty/documentation/jetty-12/programming-guide/index.html#pg-server-websocket-jetty

The problem with the Jakarta APIs is that you have to block if a remote peer is slow, and this could cause scalability issues.

With the Jetty WebSocket APIs you have full control on asynchronous writes and on the demand for more WebSocket frames.

[Spandana806]

Thank you, I will try with Jetty12 APIs.