Message model objects

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

Message
A message describes the structure and content of a set of data that is exchanged between applications that send and receive the data. A message is a special kind of complex element.
Simple element
A simple element describes one or more named data fields in a message. It is based on a simple type (for example, string, integer or float). A simple element 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 describes a named complex structure within the message. The content of a complex element is defined by a complex type. A complex element can repeat.
Complex type
A complex type describes a complex structure within a message. It contains elements (simple or complex), attributes, and groups that are organized into a tree-like hierarchy.
Group
A group describes a list of elements with information about how those elements can appear in a message. Groups can be ordered (sequence or orderedSet), unordered (all or unorderedSet), or selective (choice or message). A group can repeat.
Attribute
An attribute describes an XML attribute. Attributes are very similar to simple elements, but they require special treatment when used with XML messages. In messages that are not XML messages, attributes are typically not used, but if they do appear they are treated exactly like a simple element based on the same simple type.

Global and local objects

Most 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.

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 makes 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 definition 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 an object 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 that you might require. Text entered here does not affect the processing of messages in any way.
Related concepts
Message modeling concepts
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Copyright IBM Corporation 1999, 2009Copyright IBM Corporation 1999, 2009.
Last updated : 2009-01-07 15:21:03

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