Details of generating message id are not specified by JMS specification. But when troubleshooting issues with specific JMS implementation, it is useful to know what happens. So I am trying to figure out source of excessive duplicates on our system (activemq 4.1 -- yes, ancient version, but this is production and can't be replaced on short term), and was thinking that understanding what components of the message id mean might help.
For example, id like:
(hostname)-36715-1279138635202-1:0:1:1:1
would seem to include host name, timestamp (127...), and maybe some simple byte values. I'll try looking at code, but I was hoping someone might be able to give bit more information as to what numbers might signify.