[standards-jig] JEP-0024: Publish/Subscribe - Topic based messaging

DJ Adams dj.adams at pobox.com
Sat May 11 10:26:07 CDT 2002


On Thu, Apr 25, 2002 at 11:26:27AM +0100, Dave Turner wrote:
> I'm interested in the point you raise about determining when a message is
> 'done'.  Obviously, the broker isn't the place to decide this.  The publisher
> however, having best understanding of the data, can set a TTL on the message
> and the broker can cull messages when they become too old.  That would be
> a nice option to have.  If a TTL isn't defined the message can persist forever
> making this transparent to the clients if they don't support it.

I agree totally that any TTL relates to the payload and not any part
of the actual pubsub mechanism. I think I mentioned already (somewhere,
but I can't remember where) that you could, for example, stick a
jabber:x:expire attachment to the payload. The burden on the server,
for a situation where the 'send-last-msg-on-subscribe' mechanism were
implemented, would be in this case, where the TTL would have to be 
checked and appropriately honoured so as not to send out expired data
in this circumstance.

dj



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