Most of the java websocket examples I've found have been based on, or included a messaging protocol like STOMP. This example is the result of looking at how to proxy any message content, without worrying about the messaging protocol.
Java implementation of a websocket reverse proxy. A similar method to the one described in https://www.nginx.com/blog/websocket-nginx/, but implemented in Java. This could be useful in Java application servers, e.g. Spring Boot.
There are nodejs scripts at the root level that can be used to mimic functionality required to verify the proxy server.
The common one is the websocketserver.js script, which listens
on port 9999 and echoes back any input after uppercasing it. To test the echoing behaviour
by establishing a direct connection to a websocket server, run
test_websocketserver_direct.sh
(requires node & npm to be installed)
There is also a very simple websocketproxy.js script which will proxy
the websocketserver. It listens on port 8888 and will relay all requests to port 9999.
It can be tested by running test_websocketserver_nodeproxy.sh
A simple java implementation to match this proxying behaviour is contained in the classes defined in the src folder. It is based on Spring Boot. You can build it using Gradle and run it up manually, or use the test_websocketserver_javaproxy.sh script.
The java websocket reverse proxy will listen on port 7777 and relay all requests to port 9999.
(developed on macOS, ymmv on other platforms)