Message modeling is a way of predefining the message formats that are used by your applications.
When you have modeled your messages, products like WebSphere Message Broker can use your message models to automatically parse and write your message formats.
When you model messages you need to understand the following concepts:
A message set project is a specialized project (container) in which you create and maintain all the resources that are associated with exactly one message set.
A message set is a logical grouping of your messages and the objects that comprise them (elements, types, groups). A message set contains the following files:
The message set file provides message model information that is common across all the messages in the message set. You can create this information using the message set editor.
When you have created a message set, you typically import application message formats described by XML DTD, XML Schema, WSDL Files, C structures or COBOL structures, creating and populating message definition files. You can then edit the logical structure of your messages, and create and edit physical formats that describe the precise appearance of your message bit stream during transmission, using the message definition editor. Alternatively, you can create an empty message definition file and create your messages using just the editor.
When your message definition files are complete, you can then generate the message set in a form that can be used by an application. This might be one of the following:
Messages can be optionally grouped into message categories, both for convenience and to aid the generation of WSDL. You can add messages to message categories using the message category editor.
Each time you save a message set file, message definition file or message category file, the content is validated to ensure that the message model that you are creating follows certain rules. There are rules for both the logical structure and the physical formats. The validation ensures the integrity of your model, but does not necessarily prevent you from saving a message model file that is not valid.
A product such as WebSphere Message Broker typically supplies a range of parsers to parse and write message formats. Each parser is suited to a particular class of messages (for example, fixed-length binary, delimited text, or XML) known as a message domain. Each message set that you create specifies a domain, which determines the parser that is used when parsing and writing messages that are defined within that message set.