How can I programmatically add a websocket endpoint in embedded tomcat?

Question

I've been trying for weeks to get websockets working with embedded tomcat. I've tried emulating the examples in the tomcat unit tests to no avail. This is the first time I've tried to use websockets so I'm likely making a foolish mistake. Does anyone have any simple "Echo" examples for embedded tomcat websockets?

public void run() {

    if(!new File(consoleAppBase).isDirectory())
    {
         consoleAppBase = Paths.get("").toAbsolutePath().toString() + File.separatorChar + "wepapp";
    }

    tomcat = new Tomcat();

    tomcat.getService().removeConnector(tomcat.getConnector()); // remove default
    tomcat.getService().addConnector(createSslConnector(ConfigManager.getWeb_securePort())); // add secure option

    StandardServer server = (StandardServer) tomcat.getServer();
    AprLifecycleListener listener = new AprLifecycleListener();
    server.addLifecycleListener(listener);

    try {
        SecurityConstraint constraint = new SecurityConstraint();
        constraint.setDisplayName("SSL Redirect Constraint");
        constraint.setAuthConstraint(true);
        SecurityCollection collection = new SecurityCollection();
        collection.addPattern("/*");
        constraint.addAuthRole("administrator");
        constraint.addCollection(collection);

        //create the console webapp.
        consoleContext = tomcat.addWebapp(consoleContextPath, consoleAppBase);
        consoleContext.addConstraint(constraint);

        //this allows that little login popup for the console webapp.
        LoginConfig loginConfig = new LoginConfig();
        loginConfig.setAuthMethod("BASIC");
        consoleContext.setLoginConfig(loginConfig);
        consoleContext.addSecurityRole("administrator");

        //this creates a valid user.
        tomcat.addUser(ConfigManager.getWeb_username(), Encryptor.decrypt(ConfigManager.getWeb_passwordEncrypted()));
        tomcat.addRole("admin", "administrator");

    } catch (ServletException e) {
        LogMaster.getWebServerLogger().error("Error launching Web Application. Stopping Web Server.");
        LogMaster.getErrorLogger().error("Error launching Web Application. Stopping Web Server.", e);
        return;
    }

    addServlets(); // this is where I usually call a convenience method to add servlets

    // How can I add websocket endpoints instead?

}

Answer 1

For programmatic (non-annotated) endpoints, you have to provide a class that implements Endpoint to act as the server end, and then either:

1. Deploy a class that implements ServerApplicationConfig in your WAR file, that supplies EndpointConfig information about some or all of the non-annotated Endpoint instances that were found in the WAR file, or
2. Call ServerContainer.addEndpoint() during the deployment phase of your webapp.

See the Java™ API for WebSocket, JSR 356.