subscribe semantics (auto, not ack)

[Patrick Hurley-2]

I am trying to understand the semantics and it may be that I am
looking from something that is not considered part of the protocol,
but is a server implementation issue. In any case a little clarity
would be very welcome.

The default mode on a SUBSCRIBE of auto (no transaction, no ack) -- is
the message considered sent as soon as it is sent, after getting any
other response from the client or after a clean disconnect?

More clearly not part of the protocol, I see there are two different
behaviors for queue/topic destinations. Where is a good place to read
up on these behaviors and configurations.

I have very little experience with ActiveMQ, so if some of the answers
are in my lack of domain knowledge, I apologize. Thanks
pth

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Did you get a response from this?  It would seem your observation is correct.  This is a bit strange... I think "auto" was a poor name for the default acknowledgment mode.  "none" would of been better matched to the semantics.  It's not like JMS in which auto-acknowledge in JMS means that the JMS client-side agent software does acknowledge... it's just that you're code doesn't have to do it explicitly; it's implicit on a successful return (i.e. no thrown exception) of the message handler.  I'm tempted to go and modify the wiki to point this out.  The spec seems thrown together and incomplete.  I also wonder about the interplay of transactions and the acknowledgment mode.  Does it make sense to use transactions with non-acknowledgement? (i.e. "auto" in stomp)?  I don't know.

~ David

Patrick Hurley-2 wrote:

I am trying to understand the semantics and it may be that I am
looking from something that is not considered part of the protocol,
but is a server implementation issue. In any case a little clarity
would be very welcome.

The default mode on a SUBSCRIBE of auto (no transaction, no ack) -- is
the message considered sent as soon as it is sent, after getting any
other response from the client or after a clean disconnect?

More clearly not part of the protocol, I see there are two different
behaviors for queue/topic destinations. Where is a good place to read
up on these behaviors and configurations.

I have very little experience with ActiveMQ, so if some of the answers
are in my lack of domain knowledge, I apologize. Thanks
pth

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    http://xircles.codehaus.org/manage_email