Thursday, April 11, 2013

Dealing with Occasional Message Bursts : Message Broker Use Case

Recently I came across the following requirement,

An organization has a message delivery network and an application that makes use of those messages (process them). The delivery network directly communicates with the message processing application. Things seems to be working fine on a regular day. However if the load(incurred by the delivery network) is high, some of the messages may get lost before they get processed (overflow of applications' task queue).

Message brokers are designed to cater the exact scenario. Enterprises rely heavily on their legacy systems and changing all existing integration points may not be the right solution and will never work. In the above scenario, we can place a message broker in between the message producer and message consumer. By introducing a message broker we,

1. Decouple producer/consumer in time and space (two parties need not to be functioning at the same time and the don't have to know each others existence )   
2. Reliable message processing/delivery by means of persistence and transactions.

I implemented the POC scenario using WSO2 ESB and WSO2 MB. Please find the configuration files and source code in the this location. ESB used for its JMS transport support (you don't have to change the producer code).

How to use POC config/code;

1. replace the the original axis2.xml and file found in WSO2ESB distribution with provided ones. Here I have enabled JMS sender in axis2.xml and configured connection factory params in file.
2. Create a proxy service in WSO2 ESB using provided StockQuoteProxy.xml. This proxy will accept HTTP request and write them in to a MB queue.
3. Create a new queue named 'StockQuotesQueue' in WSO2MB: this is the queue we are writing to and reading from.
4. Start server and run the servers, send some soap messages to proxy services, so that those get written to MB. 
5. Run the Receiver to retrieve messages from MB queue.

please configure ports and hosts accordingly. Refer WSO2 MB documentation as well.

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