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XQuery's Role in Data Integration

XML is now considered the de facto standard for exchanging data. The rapid growth of XML and increase of hierarchical messages present a fresh set of challenges, particularly to developers who have historically built their business processes around databases. Because relational database systems are well-established and reliable, they are unlikely to disappear any time soon. The growth of XML is forcing modern business applications to function seamlessly with both relational and XML data.

XQuery levels the data integration playing field by providing a single interface that lets developers access multiple data sources under a unifying data model. Products such as DataDirect XQuery™ from DataDirect Technologies deliver Java components that allow the developer to present and exchange relational data as XML and to process relational and XML data together.

Before XQuery, integration of relational and XML data forced architects and developers to choose from one of the following complex strategies:

• Shredding (de-composing XML into relational tables) XML data into individual relational database table columns. This process "flattens" the built-in data hierarchy and often loses internal relationships. The original XML document itself also is lost, although it can, in some cases, be reproduced from the shredded data.
• Storing the XML data as unstructured data in a relational database using the Clob data type. Clob columns can store an XML document in its entirety, preserving both the document and its internal relationships.
• Storing the XML data as a structured XML document in a relational database. This option provides a tightly coupled relationship between XML and relational data within the context of a relational database system. However, support for the co-existence of structured XML and relational data in today's relational database systems varies considerably, which makes it difficult to implement a portable and consistent data integration strategy.

Because XQuery is about seamless data integration, the middle-tier is the logical sweet spot for developers and architects to establish the solution to their most complex data integration challenges.