Websocket compression, disable 9.4

[faljse]

I´d like to disable websocket compression to reduce cpu consumption.

In 9.3 it was possible via:

WebSocketUpgradeFilter filter  =  (WebSocketUpgradeFilter)context.getAttribute("org.eclipse.jetty.websocket.server.WebSocketUpgradeFilter");
filter.getFactory().getExtensionFactory().unregister("permessage-deflate");

Is there a way to do this in jetty 9.4?

[joakime]

You can still do that, but only after the server has started.
Consider setting that up on Servlet.init() or if you are using embedded jetty, start the server first, then get the context attribute.

[faljse]

I moved the code after server.start(), but it doesn`t make a difference
My context contains those 3 Objects after server.start:

0 = {ConcurrentHashMap$MapEntry@3421} "wsSessions" -> (custom, application code)
1 = {ConcurrentHashMap$MapEntry@3422} "org.eclipse.jetty.server.Executor" -> "qtp140799417{STARTED,8<=8<=200,i=2,q=0}"
2 = {ConcurrentHashMap$MapEntry@3423} "javax.websocket.server.ServerContainer" -> 

My server init code is pretty basic, it is available here.

[faljse]

I solved it; replaced configureContext with():

public static org.eclipse.jetty.websocket.jsr356.server.ServerContainer configureContext(ServletContextHandler context) throws ServletException {
    NativeWebSocketConfiguration nativeWebSocketConfiguration = NativeWebSocketServletContainerInitializer.getDefaultFrom(context.getServletContext());
    nativeWebSocketConfiguration.getFactory().getExtensionFactory().unregister("permessage-deflate");
    org.eclipse.jetty.websocket.jsr356.server.ServerContainer jettyContainer = new org.eclipse.jetty.websocket.jsr356.server.ServerContainer(nativeWebSocketConfiguration, context.getServer().getThreadPool());
    context.addBean(jettyContainer);
    context.setAttribute(javax.websocket.server.ServerContainer.class.getName(), jettyContainer);
    if(WebSocketServerContainerInitializer.isEnabledViaContext(context.getServletContext(), "org.eclipse.jetty.websocket.jsr356.addDynamicFilter", true)) {
        WebSocketUpgradeFilter.configureContext(context);
    }
    return jettyContainer;
}

[joakime]

That is needlessly complicated.

The WebSocketUpgradeFilter can be configured directly.

// Server init code
WebSocketUpgradeFilter wsuf = WebSocketUpgradeFilter.configureContext(context);
wsuf.getFactory().getExtensionFactory().unregister("permessage-deflate");

or, from ...

// Override this method, part of WebSocketHandler, or WebSocketServlet
public void configure(WebSocketServletFactory factory)
{
  factory.getExtensionFactory().unregister("permessage-deflate");
}

or, strip it from the upgrade request from the client ...

// Override this method from WebSocketCreator
public Object createWebSocket(ServletUpgradeRequest req, ServletUpgradeResponse resp)
{
  List<ExtensionConfig> negotiated = new ArrayList<>();
  for(ExtensionConfig config: req.getExtensions())
  {
    if (!config.getName().equals("permessage-deflate"))
    {
      negotiated.add(config);
    }
  }
  resp.setExtensions(negotiated);
  // rest of your create impl here
  return endpoint;
}

[joakime]

You can even register a ServletContextListener to do it.

public class AdjustWebSocket implements ServletContextListener
{
  public void contextInitialized(ServletContextEvent sce)
  {
    NativeWebSocketConfiguration configuration = (NativeWebSocketConfiguration) sce.getServletContext().getAttribute(NativeWebSocketConfiguration.class.getName());
    configuration.getFactory().getExtensionFactory().unregister("permessage-deflate");
  }
  public void contextDestroyed(ServletContextEvent sce)
  {
  }
}

[joakime]

You can even use the JSR356 ServerEndpointConfig.Configurator to strip it from the client.

public class NoExtensionsConfigurator extends ServerEndpointConfig.Configurator
{
    @Override
    public List<Extension> getNegotiatedExtensions(List<Extension> installed, 
                     List<Extension> requested)
    {
        return Collections.emptyList();
    }
}

[faljse]

Wow, thanks!
Yes, it did seem complicated, but well.. i couldn't figure it out :)

My init code, including ServerContainer changes is now:

WebSocketUpgradeFilter wsuf = WebSocketUpgradeFilter.configureContext(context);
wsuf.getFactory().getExtensionFactory().unregister("permessage-deflate");
ServerContainer sc= new ServerContainer(wsuf.getConfiguration(), server.getThreadPool());
context.addBean(sc);

[joakime]

Don't initialize the ServerContainer yourself, that won't work reliably. (esp knowing what's coming with the javax.websocket 1.1 support soon)

Why are you using JSR356? It's a very naive API, and your needs have already outgrown it (as evidenced by you need to configure things that are not exposed by the JSR356 API). Would encourage you to look at / use the Native WebSocket API in Jetty, as things get much simpler, and far more powerful (configurable).

If you need to stick with JSR356, then use the ServletContextListener approach, it will be the most reliable, as it configures the container after it has has started, and before any connections have been attempted.