Message model objects: groups

A group is a list of elements that defines how those elements can appear in a message.

Groups can be ordered (sequence or orderedSet) unordered (all or unorderedSet), or selective (choice or message). Groups define the composition and content validation of a set of type members.

What are groups for?

Groups can be used for any of the following purposes:

Contents of a group

Groups can contain complex elements, simple elements, wildcard elements and groups.

By combining these components, the structure of any message can be modelled. Wildcard elements can be included to allow unmodelled elements to appear, thus making the message model robust and flexible.

Global and local groups

Groups can be global or local.

A global group can be used in more than one place in the message model. It represents a structure that appears in more than one place in the message model. A global group must be given a unique name by which it can be referenced.

A local group is defined in one position within one group, and is not available for reuse elsewhere in the message model. Local groups do not have a name, and are displayed using the group's composition by the message definition editor.

Composition

In XML Schema, a group can have its composition set to sequence, all, or choice.

The message model also allows other compositions: orderedSet, unorderedSet, and message. For more information, see Schema extensions in the message model.

Content validation

Content validation determines how strictly the content of the group should be validated. See MRM content validation for more details.

Allowable values of the Content validation property are:
Closed
The contents of the group are validated strictly against the model. Only elements that are defined as children of the group can appear as children.
Open Defined
Elements that are declared within the same message set can appear as children of the group, even if they are not defined as children.
Open
Any elements can appear as children of the group.

The Content validation property does not affect validation in the XMLNSC domain. Validation in these domains follows the rules of XML Schema 1.0.

Related tasks
Adding a global group
Related reference
Message Definition editor
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Copyright IBM Corporation 1999, 2009Copyright IBM Corporation 1999, 2009.
Last updated : 2009-01-07 15:21:02

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