[openamq-dev] Named & Persistent Queue Status

[Pieter Hintjens]

On Nov 16, 2007 10:55 PM, Matthew Alton <simplicissimus at gmail.com> wrote:

>   I have a question for you about current and planned features in
> OpenAMQ.  My research has turned up conflicting information on whether
> classical persistent queues are being implemented.

The web page is somewhat optimistic.  We have focussed, and will
continue to focus, on making the software as simple and reliable as
possible, and add functionality only when there are users demanding
(and hopefully willing to pay) for it.

There is a simple way to do persistent messaging, and this should
probably be documented as a tutorial.  This is how we do large-scale
reliable messaging over OpenAMQ in deployments that need it.

First, we accept that the broker can in theory crash or disappear and
lose messages.  We construct our reliable messages as a request + ack
pair, from sender to recipient.  That is, one message to the
recipient, and a response back.  Senders store their outgoing messages
in a databaseand if they do not receive a response back within a short
time, they resend the request.  Recipients, if they get the same
request again, just resend the response but don't do the work again.

This should probably be built as a simple reusable framework around
wireapi, using sqlite or something.

The advantages of this model, over putting reliability inside the
broker, is that it works across any kind of AMQP broker, across
OpenAMQ clusters, federations, etc.

The disadvantage is that it needs extra libraries - which we have not
yet made - to be really easy to use.

The approach is very different from that used by MQ series, where the
queues themselves are persistent and reliable, and the brokers are big
and fat and complex.

>   Also, I have access to FreeBSD/SPARC64, AIX and HP-UX machines with
> C compilers.  Would it be helpful if I were to try to build OpenAMQ on
> these machines?

Yes, the more systems we test on, the better.  Afaik people have
tested on AIX but not on HP-UX.

-Pieter