Many times when I use JBossESB something does not work, because of configuration issues. In complex ESB its not obvious what is wrong. I do know I can use tracing with system.out's, but is there any way to use debug to detect those configuration errors?
I do not have any experience with debugging JBoss Server or JBoss ESB code.
Probably the best thing to do is use small service configurations and make liberal use of org.jboss.soa.esb.actions.SystemPrintln.
It's also possible to attach the source to a tool like JBDS (or Eclipse, or Netbeans, etc.) and debug that way.