concurrentConsumers in JMS endpoint creating multiple messages

[jamie3_james.archibald]

I have a camel route as follows:

from("activemq:topic:MyTopic?concurrentConsumers=3&deliveryPersistent=false")

to("activemq:topic:AnotherTopic")

The messages that are being delivered to the MyTopic are as follows:

Msg1

Msg2

Msg3

And the output to AnotherTopic is:

Msg1

Msg1

Msg1

Msg2

Msg2

Msg2

Msg3

Msg3

Msg3

For some reason the concurrentConsumers option is telling camel to triplicate the message across 3 threads, thus in turn producing 3 of the same message on AnotherTopic.

Not sure why this is happening. Any help is much appreciated.

[davsclaus]

Hi

When using concurrentConsumers with topics the ballpark changes as with topics each consumer gets a copy.

How is you JMS configuration. To avoid duplicates with topics you need to configure it a bit different. Cant quite remember. The people at the FUSE MQ forum might remember this better than I.

See the wiki page:

http://camel.apache.org/jms.html

Could be that you need to tweak the consumerType option.

[davestanley]

Hi Jamie,

I think this is expected behaviour as a Topic is used (each concurrent consumer is effectively a subscriber to the topic). If you want to do loadbalancing, then you could switch to using a queue:

from("activemq:queue:MyQueue?concurrentConsumers=3&deliveryPersistent=false")

to("activemq:queue:AnotherQueue")

or alternatively maybe use a seda component in the middle:

from("activemq:topic:MyTopic).to(seda:msgs);

from(seda:msgs?concurrentConsumers=5).to(activemq:topic:AnotherTopic);

Regards

/Dave

Edited by: dstanley on Mar 27, 2009 4:26 PM

[jamie3_james.archibald]

ok makes sense. the documentation for camel didn't provide these details.

the seda will work for now.

much thanks

.

[davestanley]

One thing I just realized is that the concurrentConsumers option for the seda component is only in Camel 1.6.1/2.0. You might need to use a snapshot for now until the next Fuse MR 1.x release to be able to use this feature of the seda component.

[jamie3_james.archibald]

Yeah I noticed this as well. Unfortunately the 1.6.1 snapshot isn't available from their website at the moment.

I will eventually move to 2.0 but not at the current time.

.