XML Schema Integration and E-Commerce

XML (eXtensible Markup Language) is used to describe semi-structured data, i.e., irregular or incomplete data whose structure may be subject to unpredictable changes. Unlike traditional semi-structured data, XML documents are self-describing, thus XML provides a platform-independent means to describe data and, therefore, can transport data from one platform to another (Bray, Paoli, & Sperberg-McQueen, 1998). XML documents can be both created and used by applications. The valid content, allowed structure, and metadata properties of XML documents are described by their related schema(s) (Thompson, Beech, Maloney, & Mendelsohn, 2001). An XML document is said to be valid if it conforms to its related schema. A schema also gives additional semantic meaning to the data it is used to tag. The schema is provided independently of the data it describes. Any given data set may rely on multiple schemas for validation. Any given schema may itself refer to multiple schemas.