JGroups is a toolkit for reliable multicast communication. (Note that
this doesn't necessarily mean IP Multicast, JGroups can also use
transports such as TCP). It can be used to create groups of processes
whose members can send messages to each other. The main features include

* Group creation and deletion. Group members can be spread across
LANs or WANs
* Joining and leaving of groups
* Membership detection and notification about joined/left/crashed members
* Detection and removal of crashed members
* Sending and receiving of member-to-group messages (point-to-multipoint)
* Sending and receiving of member-to-member messages (point-to-point)

To use JGroups one needs:
commons-logging.jar
log4j.jar

To run JGroups you need to have an XML parser installed on your system.
If you use JDK 1.4 or higher, you can use the parser that is shipped with it.

If you want to use the JGroups JMS protocol ( org.jgroups.protocols.JMS ),
then you will also need to place jms.jar somewhere in your CLASSPATH.

Place the JAR files somewhere in your CLASSPATH , and you're ready to start
using JGroups.