 by Thomas Erl |
XML Data Strategy | |
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| Whether you use XML for content management, or as a universal data transfer format, there will come a time when you will need to begin authoring custom Schemas or DTDs. Data modelling with XML is much like modelling data for relational databases, and standards used to ensure consistency are just as important to future integration and interoperability requirements. |
| If you’re just beginning to incorporate XML into your enterprise, there is no better time to think of assigning someone the responsibility of owning and maintaining the format, structure, standards, business rules, and validation rules associated with your XML documents. The XML & Web Services Integration Framework (XWIF), part of the SOA methodology developed by SOA Systems, defines this role and calls it the "XML Data Custodian." |
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Ownership of XML Vocabularies |
| The XML Data Custodian will need to create new vocabularies on-demand for XML developers who need to work with corporate data in an XML format, and have to maintain and coordinate these vocabularies. This involves ensuring that XML tags produced for vocabularies correspond correctly to definitions of the same data already residing in databases, and also trying to prevent the creation of any redundant or duplicate meta tags for the same corporate data sets (even if the same corporate data exists in different repositories). |
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Ownership of DTDs or XML Schemas |
| Depending on which type of data validation method your organization standardizes on, one person should be in control of how this validation and document structure technology is designed. DTDs and XML Schemas contain DDL-like information that defines the structure of an XML document, the data types allowed, validation rules, and other business rule-like functionality. |
| Generally, every XML document will need to be linked to a DTD or XML Schema. So, in addition to providing an overall vocabulary, the XML Vocabulary Custodian will need to assist in defining the hierarchical structure of XML documents, as well as the contents of data integrity rules. Again, the additional challenge here is to keep this information synchronized with the data integrity and referential integrity rules already in existence in corporate repositories. |
| Additional complexities can be anticipated if XML is playing an application interoperability role, where data from multiple data sources is being merged. Here the DTD or XML Schema may need to represent data integrity rules for each repository. |
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Namespace Domain Administration |
| Finally, the responsibility of namespace partitioning will likely also be assigned to this role. Namespaces allow for the definition of a domain in which vocabularies are valid. Theoretically, an organization could be partitioned into several namespaces in which independent vocabularies could exist. |
SOA: Principles of Service Design by Thomas Erl  An in-depth guide dedicated to service engineering with a thorough exploration of the design principles that comprise the service-orientation design paradigm (including a comparison with object-orientation). 
Service-Oriented Architecture:Concepts, Technology, and Design by Thomas Erl The first "how-to" guide to building SOA, providing coverage of WS-* specifications, .NET and J2EE platforms, and step-by-step processes for service-oriented analysis and design. 
Service-Oriented Architecture:A Field Guide to Integrating XML and Web Services by Thomas Erl The best-selling guide to service-oriented integration, providing hundreds of integration strategies and over sixty best practices. For more information about either book, visit: www.soabooks.com |
About SOA Systems
SOA Systems Inc. provides strategic SOA consulting services and offers a comprehensive SOA training program. For more information see: • www.soasystems.com • www.soatraining.com |
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