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From magellings <mark.gelli...@qg.com>
Subject Re: Apache NMS 1.2.0 RC1 now ready for download.
Date Fri, 11 Dec 2009 20:30:35 GMT

K.  This makes sense.  Thanks for the explanation/clarification Tim.


Timothy Bish wrote:
> 
> On Fri, 2009-12-11 at 10:09 -0800, magellings wrote:
>> So when assigning a delegate (e.g. OnMessage) to the Listener event on
>> the
>> message consumer, the framework can't pull for another message after the
>> scope of the delegate ends?  Is this how the java implementation behaves? 
>> This isn't a big deal, we already were defaulting to doing pulls manually
>> with MessageConsumer.Receive if prefetch is set to zero.  I guess just in
>> my
>> head I expected it to do it automatically even with the listener event
>> assigned.
> 
> This is exactly how the Java and C++ clients behave as well, and its by
> design.  If you want an asynchronous consumer then you need to set a
> prefetch of at least one, then when a message is available the broker
> will dispatch it, otherwise there's no traffic needed between client and
> broker other than the keep alive commands.  The prefetch zero
> functionality was introduced into AMQ for the purpose of having a
> polling only consumer model.
> 
> We want to try to keep the openwire clients as close in functionality as
> possible so that using them is as seamless as possible.  
> 
> Regards
> Tim.
> 
>> 
>> http://activemq.apache.org/what-is-the-prefetch-limit-for.html 
>> 
>> "Specifying a prefetch limit of zero means the consumer will poll for
>> more
>> messages, one at a time, instead of the message being pushed to the
>> consumer."
>> 
>> -Mark
>> 
>> 
>> Timothy Bish wrote:
>> > 
>> > On Fri, 2009-12-11 at 08:38 -0800, magellings wrote:
>> >> Hey Tim.  Could you explain this a bit more?  How come this isn't
>> >> possible. 
>> >> Seems like it should be.  Thanks :-)
>> >> 
>> >>
>> Quad.NMS.Integration.Test.PrefetchZeroPullTest.Should_be_able_to_set_prefetch_to_zero_and_nms_activemq_enables_pull_mode
>> >> : Apache.NMS.NMSException : Cannot set Asynchronous Listener on a
>> >> Consumer
>> >> with a zero Prefetch size
>> > 
>> > With prefetch set to zero there is never going to be any messages
>> > delivered from the broker.  The perfetch zero setting basically turns
>> > your client into a pull consumer, each time you call
>> > IMessageConsumer.Receive a MessagePull command it sent to the Broker,
>> if
>> > a message is available then one is delivered to the client.  With an
>> > asynchronous consumer there is nothing to initiate the MessagePull from
>> > the broker, so you'd never receive a message.
>> > 
>> > Regards
>> > Tim.
>> > 
>> >> 
>> >> 
>> >> Timothy Bish wrote:
>> >> > 
>> >> >                       ***** ANNOUNCEMENT *****
>> >> > 
>> >> > The Apache NMS 1.2.0 Release Candidate 1 is now available at the
>> >> > following location:
>> >> > 
>> >> > http://people.apache.org/~tabish/nms-1.2.0-RC1
>> >> > 
>> >> > The following projects are included:
>> >> > 
>> >> > Apache.NMS
>> >> > Apache.NMS.ActiveMQ
>> >> > Apache.NMS.EMS
>> >> > Apache.NMS.MSMQ
>> >> > Apache.NMS.WCF
>> >> > 
>> >> > There are release binaries and debug binaries (with PDBs) provided.

>> >> The
>> >> > binary ZIP files include pre-built assemblies for all of the
>> platforms
>> >> > that are supported by each project (e.g., .NET 2.0, Mono, .NET 3.5,
>> >> > etc).  Not all projects support all platforms.  Please note that in
>> >> > order to use the Apache.NMS.EMS project files, you will need to
>> provide
>> >> > your own copy of the TIBCO.EMS.dll, as this is a licensed 3rd Party
>> >> > application.
>> >> > 
>> >> > Please report any issues or problems you have with these files.
>> >> > 
>> >> > Regards
>> >> > Tim Bish
>> >> > 
>> >> > 
>> >> > 
>> >> 
>> > 
>> > 
>> > 
>> 
> -- 
> Tim Bish
> http://fusesource.com
> http://timbish.blogspot.com/
> 
> 
> 
> 
> 

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