WebSphere Message Brokers
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Writer: Terry Cowling

Concept topic

This build: July 31, 2007 21:21:42

TDS format

The Tagged/Delimited String format (TDS) is the physical representation of a message that has a number of data elements separated by tags and delimiters.

The TDS physical format is designed to model messages that consist of text strings. Examples of TDS messages are those that conform to the ACORD AL3, EDIFACT, HL7, SWIFT, and X12 standards. The TDS physical format allows a high degree of flexibility when defining message formats, and is not restricted to modeling specific industry standards. You can therefore use the TDS format to model your own messages.

TDS message characteristics

There are a number of features of text string messages that are common across many formats. This is an overview of the main features that are supported by the TDS physical format:

Tags
The text strings in the message can have a tag or a label preceding the data value. The tag is a string that uniquely identifies the data value. The TDS format allows you to associate a tag with each element when you define the element.
Delimiters and tagged data separators
The message can contain various special characters or strings in addition to the tags and text string data values. The TDS format supports a number of different types of special characters or strings.

Some messages have a special character or string that separates each data value from the next. In the TDS format this is a known as a delimiter.

In formats that have a tag before each data value, the tag can be separated from its data value by a special character or string. In the TDS format this is known as a tag data separator.

Group indicators and terminators
A message can be split into a number of substructures in a similar manner to a to COBOL or C structure. You can model each of these substructures separately by defining groups, complex types or elements for each one.

A substructure can have a special character or string that indicates its start within the data. This is known in the TDS format as a group indicator.

A substructure can also have a special character or string that indicates its end in the data. In the TDS format, this is known as a group terminator.

A group indicator and group terminator can also be defined for the whole message. Group indicators and group terminators are optional for the message and each substructure.

Fixed length strings
Some text strings within a message can be of fixed length, so a delimiter between each data value is not necessary. This is supported by the TDS format.
Fixed length tags
Some tags can be defined as fixed length, so that a tag data separator is not necessary.
Separation types
The TDS property that controls the way text strings are separated is Data Element Separation. It has several options that let you choose, for example, if tags are used, if strings lengths are fixed or variable, and what types of text strings are permitted.

The substructures within a message can use different types of data element separation and use different special characters. Therefore the TDS format allows you to define different types of data element separation and special characters for each complex type within the message.

Regular Expressions
If you choose the Use data pattern option for Data Element Separation, you can use regular expressions to identify parts of the message data to be assigned to sub-fields. This is done by setting the regular expression in the Data Pattern property.

The diagram below shows an example data message with each of its components labeled.

This diagram shows an example data message with each of its components labeled.
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Copyright IBM Corporation 1999, 2007Copyright IBM Corporation 1999, 2007. All Rights Reserved.
This build: July 31, 2007 21:21:42

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