Mapping DTDs to object-oriented schemas

As a subset of SGML, XML (Extensible Markup Language) is becoming a dominant standard for representing data in the World Wide Web and therefore the efficient treatment of XML data is important for information transfer over a network. One way towards this goal is to integrate database technology into document management and bring the very nature of database systems into this area, such as query processing, efficient management of secondary storage, version and update control, etc. We propose a new method to map DTDs (Document Type Definition) into object-oriented schemas. In this way, any complicated DTD structure can be treated uniformly. That is, using the concepts of classification/generalization and aggregation of the object-oriented model, any complex nested and recursive structure in a DTD as well as multiple appearance of element types can be represented. These issues can not be addressed if we map a DTD into a relational schema.