GWT 2.8 websocket support

Question

Does jetty server in gwt 2.8 support websocket now? As I know it did not support before. If there is a positive answer, then how to make it work? Stripping out jetty-8 and replaceing it with jetty-9 is not a good idea I think.

Answer 1

then how to make it work?

I want to elaborate a bit on this after the GWT 2.8.0 release. The only thing required for using javax.websocket is the knowledge of the Jetty version packaged with GWT and the following set of Maven dependencies (see also the Jetty WebSocket examples on GitHub):

<project>
  <properties>
    <sdm.jetty.version>9.2.14.v20151106</sdm.jetty.version>
  </properties>

  <dependencies>
    <dependency>
        <groupId>org.eclipse.jetty.websocket</groupId>
        <artifactId>websocket-server</artifactId>
        <version>${sdm.jetty.version}</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.eclipse.jetty.websocket</groupId>
        <artifactId>javax-websocket-server-impl</artifactId>
        <version>${sdm.jetty.version}</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>javax.websocket</groupId>
        <artifactId>javax.websocket-api</artifactId>
        <version>1.0</version>
        <scope>provided</scope>
    </dependency>
  </depencies>
</project>

Make doubly sure that the scope is provided - for the former two this will mean they are not packaged into the final app - you will be requiring those only when running the SuperDev-Mode (SDM). Ifjava.websocket-apiwas on your classpath probably the annotation-based configuration will not work at all (at least in embedded Tomcat and Jetty) due to the annotations being picked up by the wrong class loader (see also related question WebSocket 404 error for more info on this topic).

Answer 2

GWT 2.8 has switched to Jetty 9.2, and now supports Servlets 3.1 servlets container initializers, which I think are being used to setup WebSockets.
I haven't tried it but I suppose that you can now have WebSockets in DevMode, provided you add the required dependencies to the classpath.

You can also simply use a separate server rather than the one embedded into DevMode.