13.5 Best practices

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13.5 Best practices

Some best practices for JMS and WebSphere MQ are:

• Use message timeouts.

  Using message timeouts avoids large numbers of messages remaining on a queue, thus reducing performance overheads. It also allows the relevance of messages to be evaluated. For example, a message may not be relevant after a certain period of time because the information has been superseded.

• Use message selectors.

  Message selectors allow the underlying provider (through JMS) to browse messages before they are retrieved with little application code.

• Persistent versus non-persistent.

  Only use durable messages when necessary. This option needs to be explicitly set to non-persistent, as the default in JMS is persistent.

• Clusters.

  The use of IBM WebSphere MQ clusters allows simple administration, and automatic workload management and failover.

• Message producers.

  EJB message producers: In a request/reply scenario, it is important that the issue of blocking calls is dealt with correctly. Essentially, EJBs should only be used with appropriate request/reply timeouts and retries.

• Message consumers.

  Message-driven beans: Business logic should not be implemented in the message-driven bean. Implement the business logic in another component, such as a session bean, and use message-driven beans only for receiving the message. Never throw application exceptions in the onMessage method.

• Consider using XML-based messages for inter-application integration.

  XML is commonly used as a messaging structure that allows for a more portable inter-application integration model. Although it does add some overhead to the message payload size and requires XML parsers, it is quickly becoming a standard for inter-operability.

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