If you have cloned the source using git, you will be able to simply run Ant in the 'testfrontend' folder. To learn more about Ant and download the installer, go to http://ant.apache.org/
Once you have successfully built the project, cd to the target release folder. On Windows systems, running launch.bat will launch the Jam Test Front End. For Linux, run using launch.sh.
The GUI shows the parameters to be set in Jam to communicate with it. When Jam successfully communicates with the test front end, the GUI shows appropriate verbose messages, and sends appropriate replies, depending on state.