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From "John O'Hara" <john.r.oh...@gmail.com>
Subject Re: Message history and replay
Date Wed, 24 Jan 2007 23:19:08 GMT
We will be supporting replayable messages.
It's one of the first 'services' that we as users of other middleware have
built when it doesn't exist.

As Colin points out (and all the FIX users in the world) this is not a
strange requirement, and our applications have had call to use the facility
very routinely.

A queue is a store, it is a resouce.  That makes Qpid a resource manager.
Obviously you shouldnt store messages in queues for ever, but it is a valid
first-class persistent-store for data between applications.

Performance in this type of application (to say 1000 messages per second
de-queuing) is achieve by running larger transactions against the queue and
committing in batches.  This enables the slow part of the operation, the
write to the log/journal (dept on architecture choice) to happen less
frequently.

John



On 24/01/07, Robert Greig <robert.j.greig@gmail.com> wrote:
>
> On 24/01/07, Marnie McCormack <marnie.mccormack@googlemail.com> wrote:
>
> > I can see how this would help, but I do think we need to consider the
> likely
> > performance trade-off for persistent messaging very carefully in this
> > solution. It's hard to make persistent messaging really quick anyway (or
> at
> > least other messaging vendors find it hard :-) so we'll need to test
> > comparatively so users would understand the 'cost' of replay-ability.
>
> I think that users make the messages replayable in some other way if
> the messaging system does not support this (e.g. slap them into a
> database before putting them onto the queue is an obvious example...).
> That is almost certainly more expensive in terms of performance than
> the messaging system making them replayable via its store
> implementation.
>
> RG
>

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