I'm looking for a JAVA open source 'push' (publish/subscribe) server. 
I'll explain in case this goes by another name now.  There used to be
a product like this called Ambrosia however it no longer exists.  This
is how the server would operate.  A client application would connect
to the server via TCP/IP and 'subscribe' to some 'category', for
example 'stocks.ibm'.  The server would then log your request. 
Another client could then connect to the server and 'publish' some
data to a category, let's say 'stocks.ibm' again.  The server would
take that publish request and send that information to all clients
that 'subscribed' to that category.  It's important that I be able to
connect via TCP/IP so it would need to be some kind of server.  Any
help would be greatly appreciated.  Thank you for your time.