Thursday, August 8, 2013

JMS Message Store and JMS Message Processor Behavior - WSO2 ESB - Part 1

I have seen lot of users of WSO2 ESB misunderstood the usage of "Message Stores" and "Message Processor" of the WSO2 ESB. In this Blog series, I will explain further about "Under the Hood" functionalists of the "Message Stores" and "Message Processor" to clear the doubts and myths behind those.

Lets take a very simple use case that i have illustrated bellow,

End of the day, Client is sending a message to Backend in this scenario. Nevertheless, under the hood we are persisting message in JMS queue using "Message Store" and sending it to backend using "Message Processor". This will make sure, we never loss any transaction even backend is fail.
When backend is up and running "Message Processor" send the persisted messages to Backend.

Lets try this concept using WSO2 ESB and ActiveMQ as a message broker. Please refer [1] to understand how to configure WSO2 ESB and ActiveMQ. 

As a Backend and Client, I am using WSO2 ESB SimpleStockQuoteService and Axis2 Client. Please note that, these are packed with WSO2 ESB by default. You can find more detail in [2].

Please refer to the Synapse configuration that has been given bellow which demonstrates the concept above. 

 Use the ant command as given bellow in order to invoke the proxy from client.

ant stockquote -Daddurl=http://localhost:9000/services/SimpleStockQuoteService -Dtrpurl=http://localhost:8280/services/MessageReciveProxy -Dmode=placeorder

As result you, can notice in the Backend, there will be transaction has happened. So underneath, our "MessageReciveProxy"  Proxy received the message and persisted in "JMSMessageStore"  Message Store. Thereafter, "SampleMessageForwardingProcessor"  Message Processor took the message from "JMSMessageStore" and send it to Backend for further process.

So far so good! Hmmmm

In my next post I will introduce the evil ;)

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