The Oracle Java SE will run a nifty code example illustrating UDP Client / UDP Server communication, the source is found at:
...I copied the above source into two files, UDPClient.java and UDPServer.java, editing the UDPClient.java to use the IP address of my Infocast.
The client and server code was compiled on my WinXP machine using the following .cmd script (or just type it in by hand):
:: Simple batch file to Compile and build the UDPClient.java and the UDPServer.java application.
:: set the locations CHANGE THESE PATHS TO POINT TO YOUR JAVA JDK
set JAVACPATH="E:\Program Files\Java\jdk1.6.0_24\bin"
set JARPATH="E:\Program Files\Java\jdk1.6.0_24\bin"
:: Compile the client
%JARPATH%\jar cvfm UDPClient.jar Manifest.txt *.class
:: Compile the Server
%JARPATH%\jar cvfm UDPServer.jar Manifest.txt *.class
:: End of myUDPProject.cmd
Then I copied the UDPServer.jar to /mnt/usb/
and ran it using the following (while connected using an SSH session):
java -jar ./UDPServer.jar
...On the WinXP computer I started the UDPClient.jar from the command line using java -jar ./UDPClient.jar
Typing text on the WinXP machine then pressing <Enter> sends that text to the Infocast, which converts the text to upper case and sends it back to the client. The client exits, but the server keeps running until you press <CTRL-C>.
Only one server instance is allowed on a port at a time; starting a second server instance on the same port will display "Address already in use" error.