On 14 Jun 2008, at 01:50, Joshua Smith wrote:
All-
I'm reading a number of references on JMS written some time between
2001 and
now. The challenge that comes with that is knowing which things are
still
true today and which things were describing the state of affairs at
that
time. I found the following paragraph in the O'reilly Java Message
Service
(First Edition) book written in 2001 on p. 32. Can anyone confirm
that this
is still an accurate description of JMS?
"The Chat application ((which is what they use for their JMS example
in the
book)) uses a separate session for the publisher and subscriber,
pubSession
and subSession, respectively. This is due to a threading restriction
imposed
by JMS. ***According to the JMS specification, a session may not be
operated
on my more than one thread at a time.*** In our example, two threads
of
control are active: the default main thread of the Chat application
and the
thread that invokes the onMessage() handler. The thread that invokes
the
onMessage() handler is owned by the JMS provider. Since the
invocation of
the onMessage() handler is asynchronous, it could be called while
the main
thread is publishing a message in the writeMessage() method. If both
the
publisher and subscriber had been created by the same session, the two
threads could operate on these methods at the same time; in effect,
they
could operate on the same TopicSession - a condition that is
prohibited."
(emphasis mine)
Thanks,
Joshua Smith
Hi Joshua,
I used to have a copy of that book somewhere!
Yep - its still an accurate description of JMS
cheers,
Rob
http://open.iona.com/products/enterprise-activemq
http://rajdavies.blogspot.com/
