XQuery provides an easy, efficient way to create data services, exposing XML-based, abstracted interfaces to a variety of heterogeneous data sources. The availability of robust, scalable, and performant implementations makes XQuery one of the best options in the data management area in support of SOA and service-oriented computing. The same level of modularity, reuse, and business agility that IT organizations have already started to appreciate within the business service layer of established service inventories can now be realized within the data service layer as well.

The fundamental goal of SOA is to facilitate business-level software modularity and allow for rapid reuse of application and data logic, enabling the enterprise to be responsive and agile. In reality, most SOA projects are focused on existing application logic, and therefore fail to consider the key implications of integrating data. The common difficulties associated with accessing a large number of heterogeneous data sources represents a level of design complexity that, when ignored, will only get worse over time. The XQuery language has become an integral technology for connecting heterogeneous data sources within service oriented solutions. It's a natural fit for the typical XML data interchange format used in most SOA implementations and it provides powerful, cross-repository data access features without compromising scalability or performance. This article explores how the XQuery feature-set can be leveraged in support of SOA.