Tip: Use Data Dictionary Links for XML and Web Services Schemata
By Uche Ogbuji2005-04-09
Tip: Use Data Dictionary Links for XML and Web Services Schemata
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Leaving anchors for the meanings in XML nodes
When designing XML and Web services schemata you will often (and ideally) reuse data elements defined in pre-existing standards. When you do, it is extremely useful to include links to such standards, providing precise data dictionary references. In so doing, you make processing and maintenance easier to automate. This tip illustrates this practice.
In my Thinking XML column, I frequently focus on how various industries are working toward semantic transparency , which is the shared meaning of at least the framework of what is communicated in an XML document. Either the industries do so by creating complete document formats along with the semantics of all the elements, attributes, and content, or they define terms and concepts discretely and individually, independently of the documents in which they would appear. I call these approaches top-down and bottom-up , respectively, and very active communities provide useful material on each.
If you develop XML schemas for your own use or for public use, the usual sage advice is to be sure that you aren't carelessly duplicating existing work. But even if you're truly in new territory, or have good reason not to simply reuse existing languages, try as much as possible to lean on existing initiatives towards semantic transparency. This is best whether you are developing an XML format for private usage, or as a shared or public resource. You can borrow naming conventions and perhaps even schema snippets from existing vocabularies, but a less common technique for building on the work of others is to incorporate what I call semantic links into your own schemata -- special links to existing standards that define the syntactic constructs you define in your schema. This provides for a particularly rich form of data dictionaries for XML schemata. In this tip, I show how to work such links into your schemata.
Tutorial Pages:
» Tip: Use Data Dictionary Links for XML and Web Services Schemata
» What exactly is a service anyway?
» Semantic links in WS descriptions
» Wrap-up
» Resources
First published by IBM DeveloperWorks
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