Cannot read message on ActiveMQ-queue when implemented in WSO2: "Cannot display ObjectMessage body"

Cris 0
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I've just successfully implemented a JMS-message-processor in my WSO2-process. However, when logged in as an admin on the ActiveMQ console, I can view the stats of the queue but I cannot access the contents of the pending message. Instead, I see this error:

Cannot display ObjectMessage body. Reason: Failed to build body from content. Serializable class not available to broker. Reason: java.lang.ClassNotFoundException: org.apache.synapse.message.store.impl.commons.StorableMessage

Accessing the contents of a pending message is possible when using the RabbitMQ, so I figured it should also be possible with this message broker.

I've found solutions online, but they don't seem to be working, or perhaps they're out of date. Can somebody point me to the correct answer to solve this? I'm on WSO2 Integration Studio 8.1.0 and am using ActiveMQ 5.17.1.

activemq wso2-enterprise-integrator wso2
2 Answers

It appears that WSO2 is using javax.jms.ObjectMessage despite the fact that there's a long list of reasons why doing so is a bad idea, including the issue you're currently facing, but I digress.

The problem here is that the implementation of the javax.jms.ObjectMessage (i.e. org.apache.synapse.message.store.impl.commons.StorableMessage in this case) must be on the classpath of any application which wants to deserialize that message. This class is not, in fact, on the classpath of ActiveMQ therefore the ActiveMQ web console cannot deserialize the message and display its contents (assuming those contents are human-readable in the first place). That's why a ClassNotFoundException is thrown.

You may be able to resolve the issue by putting org.apache.synapse.message.store.impl.commons.StorableMessage on ActiveMQ's classpath. Aside from that there's really nothing to be done.

I assume this is different for RabbitMQ because in that case WSO2 doesn't use the JMS API and uses the AMQP protocol which is not Java-centric like JMS.

Justin Bertram0

Justin has explained the cause of the issue and as suggested you can try adding the class to ActiveMQ runtime and see whether it resolves the issue. This class is located in the Synapse-Core(synapse-core_2.x.x.wso2vXXX.jar). But remember although this may resolve the ActiveMQ UI issue, this message is not consumable by other systems unless they know how to deserialize it.

Let me add more details on why the message is serialized. Message serialization happens when you use the Store mediator, and when you store a message with Store Mediator it is intended to be only read by a Message Processor. Simply the serialized message can only be consumed by WSO2 Message Processors. In other words, Store Mediator and the Message processors are tightly coupled.

If message serialization is an issue for you. For example, if other systems are consuming the messages that WSO2 publishes you can try using the JMS transport to produce and to consume messages from ActiveMQ. Other than that you can also consider using JMS Inbound Endpoint to consume messages, which all use standard media types when storing the message.

ycr0
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