IBM Integration Bus, Version 9.0.0.5 Operating Systems: AIX, HP-Itanium, Linux, Solaris, Windows, z/OS

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Message tree

A message tree is a structure that is created, either by one or more parsers when an input message bit stream is received by a message flow, or by the action of a message flow node.

A message is used to describe:
  • A set of business data that is exchanged by applications
  • A set of elements that are arranged in a predefined structure
  • A structured sequence of bytes
IBM® Integration Bus routes and manipulates messages after converting them into a logical tree. The process of conversion, called parsing, makes obvious the content and structure of a message, and simplifies later operations. After the message has been processed, the parser converts it back into a bit stream.

The logical tree structure is the internal (integration node) representation of a message. It is also known as the message assembly. When a message arrives at an integration node, it is received by an input node that you have configured in a message flow. Before the message can be processed by the message flow, the message must be interpreted by one or more parsers that create a logical tree representation from the bit stream of the message data.

The input node creates this message assembly, which consists of four trees:
  1. Message tree structure
  2. Environment tree structure
  3. Local environment tree structure
  4. Exception list tree structure
The first of these trees, the Message tree structure, is populated with the contents of the input message bit stream. The remaining three trees are initially empty.

The message tree is always present, and is passed from node to node in a single instance of a message flow. The root of a message tree is called Root. The message tree includes all the headers that are present in the message, in addition to the message body. If a supplied parser created a message tree, then the element that represents the Properties subtree is followed by zero or more headers.

When you design an IBM Integration Bus flow, it is essential to understand the concepts in the Message Tree copying section, and the effective way to navigate the tree. Both of these subjects can have a large impact on the overall performance of a flow. The following sections describe in more detail the considerations that you must take in to account when you develop a flow.

Parent topic: Reduce your memory usage with parsers and message trees
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