JMS Topic multiple consumers

[selezovikj <se...@gmail.com>]

When I am consuming from a JMS topic and set the concurrentConsumers property
to 5, then the same message is replicated five times. That is so, because at
the time the topic sees 5 subscribers and sends the same message to all
subscribers. This is a behaviour which I don't want, because I want to have
competing consumers, i.e. have messages consumed concurrently by multiple
threads instead of sending the same message to 5 threads.

<route>
			<from uri="jms:topic:LoggingTopic?concurrentConsumers=5"/>
			<to uri="bean:msgParser"/>
			<to uri="direct:foo"/>
</route>

To achieve what I want I guess I should have a JMS queue which will consume
messages from the topic, and then set concurrentConsumers on the queue. 
However, in that case I would have multiple routes, and to configure
multiple routes in Spring I need to use the "direct" keyword, which
unfortunately does not allow concurrentConsumers. 

<route>
			<from uri="jms:topic:LoggingTopic"/>
			<to uri="jms:queue:LoggingQueue"/>

</route>

<route>
			<from uri="jms:queue:LoggingQueue?concurrentConsumers=5"/>
			<to uri = uri="bean:msgParser"/>

</route>

This one will not work. Any advice on how to achieve what I want ? 


		
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Re: JMS Topic multiple consumers

[James Strachan <ja...@gmail.com>]

2008/10/31 selezovikj <se...@gmail.com>:
>
> When I am consuming from a JMS topic and set the concurrentConsumers property
> to 5, then the same message is replicated five times. That is so, because at
> the time the topic sees 5 subscribers and sends the same message to all
> subscribers. This is a behaviour which I don't want, because I want to have
> competing consumers, i.e. have messages consumed concurrently by multiple
> threads instead of sending the same message to 5 threads.
>
> <route>
>                        <from uri="jms:topic:LoggingTopic?concurrentConsumers=5"/>
>                        <to uri="bean:msgParser"/>
>                        <to uri="direct:foo"/>
> </route>
>
> To achieve what I want I guess I should have a JMS queue which will consume
> messages from the topic, and then set concurrentConsumers on the queue.
> However, in that case I would have multiple routes, and to configure
> multiple routes in Spring I need to use the "direct" keyword, which
> unfortunately does not allow concurrentConsumers.
>
> <route>
>                        <from uri="jms:topic:LoggingTopic"/>
>                        <to uri="jms:queue:LoggingQueue"/>
>
> </route>
>
> <route>
>                        <from uri="jms:queue:LoggingQueue?concurrentConsumers=5"/>
>                        <to uri = uri="bean:msgParser"/>
>
> </route>
>
> This one will not work. Any advice on how to achieve what I want ?

I don't understand why that one wouldn't work? i.e. you only need
competing consumers on the consuming endpoint (the second <from>)

Another thing you could try is experimenting with the underlying
MessageListenerContainer underneath the JMS endpoint; e.g. using
ServerSessionPool based one might help you process a single topic
subscription in parallel (which is what MDBs do I think)

e.g. on the JmsEndpoint's configuration try setting the ConsumerType
property enum to be ServerSessionPool

something like

JmsEndpoint endpoint = camelContext.getEndpoint("jms:whatever",
JmsEndpoint.class);
endpoint.getConfiguration().setConsumerType(ConsumerType.ServerSessionPool);

-- 
James
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