WebSphere Message Brokers
File: ad10570_
Writer: Terry Cowling

Concept topic

This build: July 31, 2007 21:23:57

Message model objects

This is an introduction to the various objects which make up a message model.

Message
A message is a set of data passed between applications. Messages must have a structure and format which is agreed by the sending and receiving applications.
Message definition
A message definition is a logical description of a message. A message definition is a collection of simple elements organized in a tree-like structure.
Simple element
A simple element describes one or more fields in a message. It is based on a simple type (for example, string, integer or float). It can repeat, and it can define a default or a fixed value.
Simple type
A simple type describes a class of data within a message. It describes the type of data (for example, string, integer or float) and it can have value constraints which place limits on the values of any simple elements based on that simple type.
Complex element
A complex element is a named structure containing simple elements within the message. Complex elements can contain other complex elements, and can also contain groups. The content of a complex element is defined by a complex type.
Complex type
A complex type describes a structure within a message. It contains elements, attributes and groups organised into a hierarchy.
Group
A group is a list of elements with information about how those elements can appear in a message. Groups can be ordered (sequence) unordered (all) or selective (choice).
Attribute
An attribute represents an XML Schema attribute. Attributes are very similar to simple elements, but they require special treatment when used with XML messages. In messages which are not XML, they are treated exactly like a simple element based on the same simple type.

Global and local objects

Many of the objects in the message model can be either global or local. A global object must have a unique name, which is used to refer to the object from one or more places in the message model. Local objects are defined and used in only one place in the message model.

You should make objects local unless they need to be used in more than one place. This reduces the probability of name clashes among the global objects in the message model, and will make the message set easier to work with.

Properties of message model objects

The properties of all message model objects are listed on the 'properties' pane of the message editor. The properties fall into three categories:

Logical
The logical properties of an object relate to the format-independent description of the object called the 'logical model'. Logical properties describe what data the object contains without saying anything about how it is written down.
Physical
The physical properties of an object describe how the object is written down. These properties control the parsing and writing of the object. There is one set of physical properties for each physical format in your message set.
Documentation
This field is present for all message model objects. It provides a standard place for any description of the object which you might require. Text entered here does not affect the processing of messages in any way.
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Copyright IBM Corporation 1999, 2007Copyright IBM Corporation 1999, 2007. All Rights Reserved.
This build: July 31, 2007 21:23:57

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