Optimizing message flow response times

When you design a message flow, the flexibility and functional capabilities of the built-in nodes often mean that there are several ways to achieve the processing and results that you require. You might find that different solutions deliver different levels of performance and, if performance is an important consideration for you, take it into account when designing your message flow

Your applications can perceive performance in either of these ways:

• The response time indicates how quickly each message is processed by the message flow. The response time is particularly influenced by how you design your message flows. Response time is discussed in this topic.
• The throughput indicates how many messages of particular sizes can be processed by a message flow in a specified time. The throughput is mainly affected by configuration and system resource factors, and is discussed in Optimizing message flow throughput, with other domain configuration information.

The web user interface enables you to view message flow statistics and accounting data, including the message flow throughput and the CPU and elapsed times for transactions in the flow. See Viewing message flow statistics and accounting data for more information about how you can access the statistical data.

Several aspects influence message flow response times. However, as you create and modify your message flow design to arrive at the best results for your specific business requirements, also consider the eventual complexity of the message flow. The most efficient message flows are not necessarily the easiest to understand and maintain; experiment with the solutions available to arrive at the best balance for your needs.

Several factors influence message flow response times:

The number of nodes that you include in the message flow

Every node increases the amount of processing required in the integration node, therefore, consider the content of the message flow carefully, including the use of subflows.

Use as few nodes as possible in a message flow; every node that you include in the message flow increases the amount of processing required in the integration node. The number of nodes in a single flow has an upper limit, which is governed by system resources, particularly the stack size. For more information about stack sizes, see System resources for message flow development.

How the message flow routes and processes messages

In some situations, you might find that the built-in nodes, and perhaps other nodes that are available in your system, provide more than one way of providing the same function. Choose the simplest configuration. Where a message flow is required to process more than a single type of record, you can create an easily extendible framework by developing a message flow structure in which there is a parse of the message to determine the type, followed by a RouteToLabel node and Label nodes for each of the types. Where a higher number of label nodes is expected, consider implementing the message parse and Label selection in one message flow, and the processing of each of the label types into separate message flows. The interface between these two flows would be through a queue.

If your message flow includes loops

Avoid loops of repeating nodes, which can be very inefficient and can cause performance and stack problems. You might find that a Compute node with multiple PROPAGATE statements avoids the need to loop around a series of nodes.

The efficiency of the ESQL

Check all the ESQL code that you have created for your message flow nodes. As you develop and test a node, you might maintain statements that are not required when you have finalized your message processing. You might also find that something you have coded as two statements can be coded as one. Taking the time to review and check your ESQL code might provide simplification and performance improvements.

The use of persistent and transactional messages

Persistent messages are saved to disk during message flow processing. You can avoid this situation by specifying that messages are non-persistent on input, output, or both. If your message flow is handling only non-persistent messages, check the configuration of the nodes and the message flow itself; if your messages are non-persistent, transactional support might be unnecessary. The default configuration of some nodes enforces transactionality; if you update these properties and redeploy the message flow, response times might improve.

Message size

A larger message takes longer to process. If you can split large messages into smaller units of information, you might be able to improve the speed at which they are handled by the message flow.

Message format

Although IBM® Integration Bus supports multiple message formats, and provides facilities that you can use to transform from one format to another, this transformation increases the amount of processing required in the integration node. Make sure that you do not perform any unnecessary conversions or transformations.

You can find more information about improving the performance of a message flow in a developerWorks® article (developerWorks article on message flow performance).