Rule-based generation of XML DTDs from UML class diagrams

We present an approach of how to extract automatically an XML document structure from a conceptual data model that describes the content of a document. We use UML class diagrams as the conceptual model that can be represented in XML syntax (XMI). The algorithm we present in the paper is implemented as a set of rules that transform the UML class diagram into an adequate document type definition (DTD). The generation of the DTD from the semantic model corresponds with the logical XML database design with the DTD as the database schema description. Therefore, we consider many semantic issues, such as the dealing with relationships, how to express them in a DTD in order to minimize the loss of semantics. Since our algorithm is based on XSLT stylesheets, its transformation rules can be modified in a very flexible manner in order to consider different mapping strategies and requirements.