Fuse ESB uses karaf server with OSGi.
for the code if anybody has steps to get the debugger for the application it will help.
I am currently using Eclipse Indigo. As OSGi is used we are using Maven to build the same.
Which plugin will help for Karaf with OSGi
Java allows you to remote debug any JVM running.
So if you start the ESB with a debug argument, then it will run in debug mode listening on port 5005.
davsclaus:/opt/fuse-esb-7.0.1.fuse-084$ bin/fuseesb debug
Listening for transport dt_socket at address: 5005
Then you can do remote debugging from Eclipse using that port number. This is standard Java remote debugging, and Eclipse has a wizard for that already. Its the debug wizard which has a remote debug functionality.