WebSphere Message Brokers
File: ad09480_
Writer: Terry Cowling

Reference topic

This build: July 31, 2007 21:23:18

Restrictions for nesting complex types

If you include a group within another group or complex type, the Data Element Separation property for the nested group must be compatible with the Data Element Separation property of the parent group or complex type. For example, you cannot set the parent property to Fixed Length and the child property to Tagged Delimited, because the length of the Tagged Delimited structure would not be known, and would therefore conflict with the parent definition. If groups are nested to three or more levels, the Data Element Separation property for each nested group must be compatible with all of its parent groups.

The rules for compatibility are listed in the table of permitted options for nested complex types shown below.

  Parent
Child Tagged Delimited, Tagged Encoded Length All Elements Delimited, Variable Elements Delimited Fixed Length, Fixed Length AL3 Tagged Fixed Length Use Data Pattern
Tagged Delimited, Tagged Encoded Length Allowed Allowed Not allowed Not allowed Allowed
All Elements Delimited, Variable Elements Delimited Allowed Allowed Not allowed Not allowed Allowed
Fixed Length, Fixed Length AL3 Allowed Allowed Allowed Allowed Allowed
Tagged Fixed Length Allowed Allowed Not allowed1 Allowed Allowed
Use Data Pattern Allowed Allowed Allowed Allowed Allowed
Note:
  1. Tagged Fixed Length cannot exist at the inner level if any outer level has a Data Element Separation method of Fixed Length or Fixed Length AL3. This is because an item of Tagged Fixed Length can repeat a variable number of times. Fixed Length and Fixed Length AL3 are parsed by moving a set number of bytes: with a variable number of repeats, it is not possible to calculate the number of bytes that need to be parsed.
Related concepts
Message modeling
The message model
TDS format: Relationship to the logical model
Related tasks
Developing message models
Working with a message definition file
Working with message model objects
Related reference
Message model reference information
Message model object properties
Additional MRM domain information
Additional TDS information
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This build: July 31, 2007 21:23:18

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