Register a WebSocketApplication to a specific context path and url pattern.
If you wish to associate this application with the root context, use an
empty string for the contextPath argument.
Examples:
// WS application will be invoked:
// ws://localhost:8080/echo
// WS application will not be invoked:
// ws://localhost:8080/foo/echo
// ws://localhost:8080/echo/some/path
register("", "/echo", webSocketApplication);
// WS application will be invoked:
// ws://localhost:8080/echo
// ws://localhost:8080/echo/some/path
// WS application will not be invoked:
// ws://localhost:8080/foo/echo
register("", "/echo/*", webSocketApplication);
// WS application will be invoked:
// ws://localhost:8080/context/echo
// WS application will not be invoked:
// ws://localhost:8080/echo
// ws://localhost:8080/context/some/path
register("/context", "/echo", webSocketApplication);