XML Schema Integration to Facilitate E-Commerce

XML has become the de facto standard for Information Exchange protocol for e-commerce and many workgroup applications such as Enterprise Resource Planning (ERP). The availability of large amounts of heterogeneous distributed web data necessitates the integration of XML data from multiple XML sources for many reasons. Currently, there are many e-commerce companies, which sell similar products but represent them using different XML schemas with possibly different ontologies. When any two such companies merge, there is a need for a uniform schema integration methodology. In some applications like comparison-shopping, there is a need for an illusionary centralized homogeneous information system. In this chapter, we propose an XML Schema integration methodology. We define an object-oriented data model called XSDM (XML Schema Data Model) and present a graphical representation of XML Schema for the purpose of schema integration. We use a three-layered architecture for XML Schema integration, with each layer presenting an integrated view of the concepts that characterize the layer below. The three layers included are namely pre-integration, comparison and integration. During pre-integration, an analysis of the schemas to be integrated occurs. During the comparison phase of integration, correspondences as well as conflicts between elements are identified. During the integration phase, restructuring and merging of the initial schemas takes place to obtain the global schema. We define integration policies for integrating element definitions as well as their data types and attributes. The policies are also applicable in integrating DTD schemas with other DTD/XML Schemas.