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Posted to users@camel.apache.org by hennejg <j....@levigo.de> on 2008/10/29 11:36:49 UTC

Howto for MessageListenerProcessor

Hi,

in this message
http://www.nabble.com/How-camel-resolve-JNDI-End-point-td13039322s22882.html#a13100603
the MessageListenerProcessor is mentioned as a possible way to feed messages
received by an MDB into camel. However, I found it rather non-obvious how
this is actually accomplished. Is there a brief howto or example of what to
provide to the MLP constructor based on a given camel context?

Thanks!
Joerg
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Re: Howto for MessageListenerProcessor

Posted by James Strachan <ja...@gmail.com>.
2008/10/29 hennejg <j....@levigo.de>:
>
> Hi,
>
> in this message
> http://www.nabble.com/How-camel-resolve-JNDI-End-point-td13039322s22882.html#a13100603
> the MessageListenerProcessor is mentioned as a possible way to feed messages
> received by an MDB into camel. However, I found it rather non-obvious how
> this is actually accomplished. Is there a brief howto or example of what to
> provide to the MLP constructor based on a given camel context?

We could do with a tutorial that shows how to invoke Camel from an MDB
- if you wanted to reuse an MDB application but just add some Camel
routing.

I've raised a JIRA to track this
https://issues.apache.org/activemq/browse/CAMEL-1033

Using trunk you can now create a JMS message listener as follows...

MessageListener listener =
CamelMessageListener.newInstance(camelContext, "direct:foo");

where "direct:foo" is whatever Camel URI you want to use to process
the incoming JMS message.

So you could wrap this up in a trivial MDB if you like to delegate
processing of the JMS message to some Camel rule.

-- 
James
-------
http://macstrac.blogspot.com/

Open Source Integration
http://fusesource.com/

Re: Error Handling & CXF Integration

Posted by Willem Jiang <wi...@gmail.com>.
Hi ,

You should get a exception from the cxf:ws endpoint in Camel 1.5. Then
you can use Camel's ErrorHandler[1] to retry or send it to a dead letter
queue.

If you are using Camel 1.4, you will not get this kind of exception, the
camel cxf endpoint just put the exception into the exchange.

[1]http://activemq.apache.org/camel/error-handler.html

Willem
Coder One wrote:
> Say I have a route from("jms:in").to("cxf:ws") and that ws link is down, what's camel behavior?  Configurable?  What's the recommended practice to work with error handling or route failure/unavailability?
> 
> Thanks,
> 
> 
> 
> 
>       
> 
>

Error Handling & CXF Integration

Posted by Coder One <co...@yahoo.com>.
Say I have a route from("jms:in").to("cxf:ws") and that ws link is down, what's camel behavior?  Configurable?  What's the recommended practice to work with error handling or route failure/unavailability?

Thanks,

Re: Howto for MessageListenerProcessor

Posted by hennejg <j....@levigo.de>.

James.Strachan wrote:
> 
> See the helper class I just created.
> 
> The other option is just create a JmsExchange object from the JMS
> Message and send that with the ProducerTemplate
> 
> 
That's exactly what I was looking for - brilliant! Thanks a lot.

Joerg
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Re: Howto for MessageListenerProcessor

Posted by James Strachan <ja...@gmail.com>.
2008/10/29 hennejg <j....@levigo.de>:
>
> Hi!
>
> thanks for your quick reply!
>
>
> Claus Ibsen wrote:
>>
>> Hi
>>
>> #1: Are you using J2EE message driven beans (EJB beans)?
>> #2: Or do you want to using Spring-based message listener (what Camel
>> uses)?
>>
>> If #1 then you can send the data from your J2EE MDB to Camel using a
>> ProducerTemplate
>> ...
>>
>
> I am using J2EE, i.e. implementing a J2EE MDB. I played around with
> ProducerTemplates but was under the impression that this is probably not the
> most elegant way. If, for example, I configure a route as
> from("direct:foo").to("stream:out"); and feed (forward) a JMS Message the
> MDB received using ProducerTemplate.sendBody("direct:foo", message), the JMS
> headers are lost and there is no automatic conversion of, say, a TextMessage
> into a String etc. as it happens with the jms:-component. I was hoping for
> the MessageListenerProcessor to do something smart with the headers, but if
> forwarding the headers separately is the recommended way to go, I'm fine
> with that.

See the helper class I just created.

The other option is just create a JmsExchange object from the JMS
Message and send that with the ProducerTemplate


-- 
James
-------
http://macstrac.blogspot.com/

Open Source Integration
http://fusesource.com/

RE: Howto for MessageListenerProcessor

Posted by hennejg <j....@levigo.de>.
Hi!

thanks for your quick reply!


Claus Ibsen wrote:
> 
> Hi
> 
> #1: Are you using J2EE message driven beans (EJB beans)?
> #2: Or do you want to using Spring-based message listener (what Camel
> uses)?
> 
> If #1 then you can send the data from your J2EE MDB to Camel using a
> ProducerTemplate
> ...
> 

I am using J2EE, i.e. implementing a J2EE MDB. I played around with
ProducerTemplates but was under the impression that this is probably not the
most elegant way. If, for example, I configure a route as
from("direct:foo").to("stream:out"); and feed (forward) a JMS Message the
MDB received using ProducerTemplate.sendBody("direct:foo", message), the JMS
headers are lost and there is no automatic conversion of, say, a TextMessage
into a String etc. as it happens with the jms:-component. I was hoping for
the MessageListenerProcessor to do something smart with the headers, but if
forwarding the headers separately is the recommended way to go, I'm fine
with that.

Joerg

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RE: Howto for MessageListenerProcessor

Posted by Claus Ibsen <ci...@silverbullet.dk>.
Hi

#1: Are you using J2EE message driven beans (EJB beans)?
#2: Or do you want to using Spring-based message listener (what Camel uses)?

If #1 then you can send the data from your J2EE MDB to Camel using a ProducerTemplate

If #2 then check out some of the spring-jms examples that is in the camel distro.


Here is a snippet from one of my proof of concept with Camel in WebSphere (#2)

    <!-- websphere JMS connection factory -->
    <jee:jndi-lookup id="wasJMSConnectionFactory" jndi-name="jms/connectionFactory"/>

    <!-- jms provider -->
    <bean id="jms" class="org.apache.camel.component.jms.JmsComponent">
        <property name="connectionFactory" ref="wasJMSConnectionFactory"/>
    </bean>

The above is standard Spring stuff doing jndi lookup in WebSphere and a JMS component in Camel that uses the WebSphere connection factory.

Then the rest is standard Camel where you can route with from("jms:MyQueueName").to("bean:doSomething");

For instance I have defined this endpoint id in camel context (XML)
        <endpoint id="gsoQueue" uri="jms:queue:gsopenInbox"/>

And then the routing in Java DSL using the endpoint id as a reference

    from("gsoQueue")
            // map the input from GS to our inhouse format
            .processRef("mapper")






Med venlig hilsen
 
Claus Ibsen
......................................
Silverbullet
Skovsgårdsvænget 21
8362 Hørning
Tlf. +45 2962 7576
Web: www.silverbullet.dk

-----Original Message-----
From: hennejg [mailto:j.henne+nabble@levigo.de] 
Sent: 29. oktober 2008 11:37
To: camel-user@activemq.apache.org
Subject: Howto for MessageListenerProcessor


Hi,

in this message
http://www.nabble.com/How-camel-resolve-JNDI-End-point-td13039322s22882.html#a13100603
the MessageListenerProcessor is mentioned as a possible way to feed messages
received by an MDB into camel. However, I found it rather non-obvious how
this is actually accomplished. Is there a brief howto or example of what to
provide to the MLP constructor based on a given camel context?

Thanks!
Joerg
-- 
View this message in context: http://www.nabble.com/Howto-for-MessageListenerProcessor-tp20224390s22882p20224390.html
Sent from the Camel - Users mailing list archive at Nabble.com.