Hi Christian,
Why don't you simply define the redelivery policy on the
TransactionErrorHandler like that :
<!-- use a transaction error handler -->
<bean id="myErrorHandler"
class="org.apache.camel.spring.spi.TransactionErrorHandlerBuilder">
<property name="redeliveryPolicy" ref="myPolicy"/>
</bean>
<!-- and let it try to redeliver up till 4 times -->
<bean id="myPolicy" class="org.apache.camel.processor.RedeliveryPolicy">
<property name="maximumRedeliveries" value="4"/>
</bean>
<camelContext xmlns="http://camel.apache.org/schema/spring";>
<!-- disable JMX during testing -->
<jmxAgent id="agent" disabled="true"/>
<route errorHandlerRef="myErrorHandler">
<!-- 1: from the jms queue -->
<from uri="activemq:queue:okay"/>
<!-- 2: mark this route as transacted -->
<transacted/>
<!-- 3: call our business logic that is myProcessor -->
<process ref="myProcessor"/>
<!-- 4: if success then send it to the mock -->
<to uri="mock:result"/>
</route>
</camelContext>
Regards,
Charles Moulliard
Sr. Principal Solution Architect - FuseSource
Apache Committer
Blog : http://cmoulliard.blogspot.com
Twitter : http://twitter.com/cmoulliard
Linkedin : http://www.linkedin.com/in/charlesmoulliard
Skype: cmoulliard
On Sun, May 22, 2011 at 6:17 PM, Christian Müller
<[email protected]> wrote:
> Hello!
>
> To illustrate the missing feature, assume we have the following route:
> from(activemq:queue:foo)
> .to("cxf:bean:orderService")
> .to("activemq:queue:bar");
>
> Our orderService is out of order every day for 30 min - 60 min. In this
> time, we cannot process messages from the foo queue. We have to delay the
> processing until the orderService returns to operate normal. We have
> multiple possibilities at present to handle the requirement, but all have
> some drawbacks, IMO.
>
> 1) Make the route transacted and let the ActiveMQ Broker do the (redelivery)
> work.
> from(activemq:queue:foo)
> .transacted("REQUIRED")
> .to("cxf:bean:orderService")
> .to("activemq:queue:bar");
>
> Drawbacks:
> - We are not the owner of this configuration cannot ensure the ActiveMQ
> broker/JMSConnectionFactory is configured properly for the redelivery.
> - We cannot use different redelivery policies for different routes.
>
>
> 2) Use the Camel dead letter error handler to catch the errors and do the
> redelivery.
> errorHandler(
> deadLetterChannel(activemq:queue:foo.DLQ)
> .maximumRedeliveries(8)
> .deliveryDelay(60000)
> .useExponentialBackOff()
> .backOffMultiplier(2));
>
> from(activemq:queue:foo)
> .to("cxf:bean:orderService")
> .to("activemq:queue:bar");
>
> Drawbacks:
> - When we are in the seventh redelivery, we will wait over one hour for the
> next redelivery. If we have to shout down our container (which is
> ServiceMix), it will take over one hour or we have to force the shutdown and
> we loose the message.
>
>
> To solve the missing feature, we have at least two options:
>
>
> a) Provide a "special" error handler which uses the "delay and schedule
> message delivery" feature from ActiveMQ [3]. This error handler should/could
> looks like the RedeliveryErrorHandler:
> errorHandler(
> activeMqDeadLetterChannel(activemq:queue:foo.DLQ)
> .maximumRedeliveries(8)
> .deliveryDelay(60000)
> .useExponentialBackOff()
> .backOffMultiplier(2));
>
> from(activemq:queue:foo)
> .to("cxf:bean:orderService")
> .to("activemq:queue:bar");
>
> If an error occurs, this error handler should evaluate the (JMS) headers
> whether or not the message should redelivered, which delay should be used,
> update the (JMS) headers with the new values and enqueue the message again
> into the queue the message was read from. May be this route must/should also
> be transacted to make sure we do not loose messages.
>
>
> b) Add the options described in [1] and [2] to the activemq component to
> allow the user to specify the redelivery behavior per endpoint definition:
> from(activemq:queue:foo?maximumRedeliveries=10&deliveryDelay=60000&useExponentialBackOff=true&backOffMultiplier=2)
> .transacted("REQUIRED")
> .to("cxf:bean:orderService")
> .to("activemq:queue:bar");
>
> This options should be used to configure the JMSConnection.
> I know it's also possible to configure this in the
> ActiveMQConnectionFactory, but:
> - We are not the "owner" of this configuration. We use an OSGI lookup to get
> the reference to the exported ActiveMQConnectionFactory.
> - It's a global configuration and we may need the possibility to override
> some options (deliveryDelay) for other routes.
>
>
> Do I miss something? What are your thoughts?
>
>
> [1] http://activemq.apache.org/redelivery-policy.html
> [2] http://activemq.apache.org/message-redelivery-and-dlq-handling.html
> [3] http://activemq.apache.org/delay-and-schedule-message-delivery.html
>
> Looking forward for many opinions :-),
> Christian
>
