Question

I’m hoping someone can explain a bit more about how to configure Camel to marshal and unmarshal data. I have a route that calls a bean in order to determine a recipientList. This is based on the contents of the message (a protobuf).

The route config looks like:-

    <route id="Splitter">
        <from uri="activemq:notification.splitter" />
        <unmarshal ref="notificationProto" />
        <recipientList>
            <method bean="NotificationSplitter" method="splitNotification" />
        </recipientList>
    </route>

The bean works fine, but the downstream routes complain that:-

org.apache.camel.RuntimeCamelException: java.lang.RuntimeException: Unable to find proto buffer class

The downstream routes have exactly the same protobuf dataFormat config as the route above. If I route directly to the downstream queues (i.e. bypass the bean and hardcode the “to” queues), which means I can also skip the unmarshalling step, it works fine.

I guess that I need to re-marshal the data before Camel puts the messages onto the destination queues but I don’t know how to configure this within the XML. I’ve tried simply adding…

<marshal ref="notificationProto" />

…after the recipientList has been determined but it doesn’t do it (I assume because Camel has already dispatched the messages by then).

An alternative could be to do the unmarshalling from within the bean as then the data on the exchange will presumably remain unaltered. I’m not quite sure how to do this. Would it work?

Thanks for any tips.

J.

Answer 1

Yeah the data formats are not an endpoint that’s easy to send a message to, as otherwise you can use the Routing Slip EIP pattern instead, and send the message to the data format first, and then the destination. http://camel.apache.org/routing-slip.html

Though you could have a little route

<route>
  <from uri="direct:marshalMe"/>
  <marshal ref="notificationProto" />
</route>

And then use the routing slip, to set to “direct:marshalMe,whereYouWannaGoNext”.

An alternative is to use an interceptor, and intercept sending to endpoints (you can filter by wildcards, or reg exps), and then do the marshal first. http://camel.apache.org/intercept
See that link for more details.