XML-based applications using XML Schema

XML Schemas provide a generalization of Document Type Definitions for describing the validity of a set of XML documents. There is a growing number of applications that deal with XML documents in various respects. One area of programs is concerned with analyzing XML documents arriving, for example, over the internet. Another rapidly expanding area is best described by the term XML generators. XML generators usually are part of a WWW system, for example generators for XML documents serving as views of data bases. Although XML Schemas provide a concise means for describing the syntax of correct XML documents in a specific domain, XML generators usually treat the XML documents as unstructured strings or, in the context of the Document Object Model, as trees the nodes of which belong to an unspecific Element-interface. The syntactical correctness, i.e. the validity of the generated XML documents cannot be guaranteed at compile time but must be tested at runtime. This means that, in general, there is no ultimate proof that an XML generator generates only valid documents according to an underlying XML schema. This paper addresses this problem by introducing a new distinct interface for each element defined within an XML schema. Each interface extends the Element-interface of the Document Object Model. This mechanism provides a generalization of a previous approach based on the weaker concept of Document Type Definitions presented by the authors.