XML Structures for Relational Data

XML is increasingly being adopted for information publishing on the World Wide Web. However, the underlying data is often stored in the relational databases. Some mechanism is needed to convert the relational data into XML data. In this work, we employ a semantically rich semistructured data model, the Object-RelationshipAttribute model for semistructured data, as a middleware to support the schema conversion from semantically enriched relational schema to XML Schema. This approach allows us to handle the translation of a set of related relations and to distinguish attributes of relationship types from attributes of object classes, multivalued attributes, and different types of relationships such as binary, n-ary, recursive and ISA. The resulting XML structures are able to reflect the inherent semantics and implicit structure in the underlying relational database. We also show that the appropriate use of references is able to avoid unnecessary redundancy and the proliferation of disconnected XML elements.