JMS redelivery with ActiveMQ and Servicemix

The other day I felt a compelling need to implement a JMS redelivery scenario. The exact scenario I’d been trying to handle was:

my message is in an ActiveMQ queue or topic
its processing fails, because of some exception – ie. database access exception due to server nonavailability
since we get an exception, the message is not handled properly, we may want to retry processing attempt some time later
of course, for the redelivery to happen we need the message to stay in the ActiveMQ queue – fetching messages from the queue will be stopped until the redelivery succeeds or expires

See how this can be done after the jump :)

For this to happen, I’ve tried implementing Apache Camel route, but as it turns out, Camel fails to deliver facilities for exact JMS redelivery. It is possible to set JMS connection in transacted mode, but the redeliveries happen one after another and fixed times.

What I’ve ended up doing was implement a servicemix-jms endpoint. I’ve used this configuration for it:


            activemq/connectionFactory

            activemq/resourceAdapter

As you can see, we lookup a couple of things in JNDI registry, so you need to have them configured on the Servicemix side – a sample config presented farther in this entry.

The bean responsible for configuring redelivery settings is activationSpec. You can set various things with it, like:

initial redelivery delay
maximum number of redeliveries
backoff multiplier
…

What is really important in jms:endpoint config for this to work are:

processorName=”jca”
rollbackOnError=”true”

Servicemix should have the following entries in its jndi registry:

          

(...) 

       xmlns:jencks="http://jencks.org/2.0"
       xmlns:amqra="http://activemq.apache.org/schema/ra" -->

When the redeliveries are exhausted, message is routed to global Dead Letter Queue called ActiveMQ.DLQ. Since this is a single bag for all the failed messages from all queues, you may want to configure this aspect differently. For example you can tell ActiveMQ to create a single DLQ for each queue. Use this config to achieve it – the changes should be made to Broker configuration.

...

More on the subject of redelivieries in ActiveMQ can be found at http://activemq.apache.org/message-redelivery-and-dlq-handling.html.

DDevelopment & Design

Grails render as JSON catch

byTomasz Kalkosiński
November 21, 2012

One of a reasons your controller doesn't render a proper response in JSON format might be wrong package name that you use. It is easy to overlook. Import are on top of a file, you look at your code and everything seems to be fine. Except response is still not in JSON format.

Consider this simple controller:

class RestJsonCatchController {
def grailsJson() {
render([first: 'foo', second: 5] as grails.converters.JSON)
    }

def netSfJson() {
render([first: 'foo', second: 5] as net.sf.json.JSON)
    }
}

And now, with finger crossed... We have a winner!

$ curl localhost:8080/example/restJsonCatch/grailsJson
{"first":"foo","second":5}
$ curl localhost:8080/example/restJsonCatch/netSfJson
{first=foo, second=5}

As you can see only grails.converters.JSON converts your response to JSON format. There is no such converter for net.sf.json.JSON, so Grails has no converter to apply and it renders Map normally.

Conclusion: always carefully look at your imports if you're working with JSON in Grails!

Edit: Burt suggested that this is a bug. I've submitted JIRA issue here: GRAILS-9622 render as class that is not a codec should throw exception

JMS redelivery with ActiveMQ and Servicemix

Tags:

Marcin Cylke

Oracle ODBC dla Windows

Creating charts in GWT was never so easy. (OFC GWT)

Grails render as JSON catch

Warsjawa – Testowanie użyteczności z wykorzystaniem użytkowników

HISE home page

JMS redelivery with ActiveMQ and Servicemix

Tags:

Marcin Cylke

Oracle ODBC dla Windows

Creating charts in GWT was never so easy. (OFC GWT)

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