Java EE 7 WebSockets Chat Tutorial

Rational

An example setting up a websocket-enabled chat system using Java EE 7, custom encoders/decoders, the new Java API for JSON Processing and bootstrapping.

Two application servers are tested:

• Wildfly,
• Glassfish.

With each server, two modes are available:

• embedded: this mode allows testing the application without requiring any standalone server already installed and running.
• standalone: this mode creates a fatjar which is able to launch a standalone server with the application running.

The post Embarquement immédiat et sans souci pour JavaEE 7 (in french) gives some more details.

Tools

With Wildfly Swarm, it's straightforward to build either of the two modes for Wildfly.

But Glassfish doesn't provide any off-the-shelf means to create a runnable fatjar. maven-embedded-glassfish-plugin is designed just to launch the server with an existing war file, nothing else.

Payara Micro can launch a standalone Glassfish server, deploying a specified war file. But again, it doesn't provide any off-the-shelf means to create a runnable fatjar.

Fortunately, with the help of Capsule, it's quite easy to wrap Payara Micro inside a fatjar.

For the time being maven-assembly-plugin is used to do the job. But starting with its version 2.6, this plugin has eratic behavior: the generated fatjar is not always runnable. See capsule and maven-assembly-plugin 4.5+ #93. It's why the version 2.5.5 is used here.

About maven-embedded-glassfish-plugin: when used on the command line, it can't be launch from the parent project but only from the module with source code, see below.

About wildfly-swarm-plugin: under M2Eclipse, don't use the profile wildfly-embedded as, with wildfly-swarm:run, the server keeps running after its shutting down has been asked. Then you would have to stop it from a console command line.

This project requires Maven 3.3.1+. When used with Maven 3.3 or below, on the command line:

• with either of the profiles glassfish-embedded or glassfish-standalone, specify also the profile glassfish,
• with either of the profiles wildfly-embedded or wildfly-standalone, specify also the profile `wildfly.

Build and running

A profile is provided for each scenario:

mvn clean package antrun:run -Pwildfly-standalone

mvn clean wildfly-swarm:run -Pwildfly-embedded

mvn clean install antrun:run -Pglassfish-standalone

cd app
mvn clean package embedded-glassfish:run -Pglassfish-embedded

Whatever the scenario, when the server is ready, go to:

   http://localhost:8084/hascode   

Note:

• The port can be changed from the parent pom file.

Todo

Add a profile payara-launcher with antrun and Payara-Micro, i.e. without using the fatjar.

Use of capsule-maven-plugin with the profile glassfish-standalone.

With this simple websocket application, Wildfly-Swarm can run it with a Undertow server, i.e. without the Wildfly server itself: the fatjar is half the size of the Glassfish fatjar. So:

• create an application which requires the Wildfly server itself, and check then the fatjar size;
• find out if there is a means to slim down the Payara fatjar.

Credits

The sample is based on:

 Creating a Chat Application using Java EE 7, Websockets and GlassFish 4
 http://www.hascode.com/2013/08/creating-a-chat-application-using-java-ee-7-websockets-and-glassfish-4/

with the code source:

 Java EE 7 - GlassFish WebSockets Chat Tutorial  
 https://bitbucket.org/hascode/javaee7-websocket-chat/