VOEvents: VOEvent is the International Virtual Observatory Alliance standard for describing transient celestial events. See more here http://www.ivoa.net/documents/Notes/VOEventTransport/
To compile: javac Client.java
To run client:
java -cp . Client
To send voevent, use comet implementation https://github.com/jdswinbank/Comet and run broker sending data/voevent.xml sample:
comet-sendvo -f data/voevent.xml