SockJS Servlet

This is an in-progress SockJS server implementation designed to run in any Java Servlet 3.1 container. Things are still a work-in-progress but very usable as-is.

All the protocols have been implemented and I've verified that a basic browser SockJS client works with the echo example on Undertow, WildFly 8, and Tomcat 8.

Releases

All releases are published to Maven Central at http://central.maven.org/maven2/org/projectodd/sockjs/sockjs-servlet/

Example Maven <dependency> entry to pull in the latest version:

<dependency>
  <groupId>org.projectodd.sockjs</groupId>
  <artifactId>sockjs-servlet</artifactId>
  <version>[0.1.0,)</version>
</dependency>

Echo Example

See our echo example for an example of building a .war that uses SockJS Servlet. The meat of the code is in the EchoServlet class. To build the example from a fresh clone of this repo:

cd examples/echo
mvn clean package

Deploy the resulting target/echo.war to your favorite Servlet 3.1 or Java EE 7 container and open http://localhost:8080/echo (or whatever host/port your container runs on) to play with the example.

Building SockJS Servlet

mvn install

Running SockJS Protocol tests

The only tests right now depend on the sockjs-protocol project. Make sure you have Python 2.x and virtualenv installed - see the sockjs-protocol README for how to do this. Once you get that done:

git submodule init
git submodule update
mvn verify -Pintegration-tests

There are a couple of tests that are expected to fail just due to differences in HTTP connection handling between Node and Servlet containers. The build won't fail if any of these expected failures occur, but will if anything unexpected fails. If there are any unexpected failures, target/sockjs-protocol-output.log and target/server-output.log are helpful in figuring out what went wrong.

Known Issues

The client's remote IP and port are not available on SockJsConnection when using websockets. This is due to a limitation of the servlet 3.1 and websocket spec in Java that gives us no way to access this information.
The client's headers are not available on SockJsConnection when using raw (non-browser) websockets. This is due to the same limitation as remote IP / port above, but when using browser-based websockets we can hack around it by storing some information keyed off the internal sockjs session id. This isn't an option when using raw websockets.
We don't immediately respond to closing of connections at the socket level and instead wait for the next heartbeat interval to realize the client closed the connection. The exception to this is if a new connection is opened with the same SockJS session id - in that case we actively check if the old connection is still working by sending down a heartbeat frame. If that fails, then we mark the old connection as closed and allow the new connection to open.

projectodd / sockjs-servlet