UML and XML Schema

XML is rapidly becoming the standard method for sending information across the Internet. XML Schema, since its elevation to W3C Recommendation on the 2nd May 2001, is fast becoming the preferred means of describing structured XML data. However, until recently, there has been no effective means of graphically designing XML Schemas without exposing designers to low-level implementation issues. Bird, Goodchild and Halpin (2000) proposed a method to address this shortfall using the 'Object Role Modelling' conceptual language to generate XML Schemas. This paper seeks to build on this approach by defining a mapping between the Unified Modeling Language (UML) class diagrams and XML Schema using the traditional three level database design approach (ie. using conceptual, logical and physical design levels). In our approach, the conceptual level is represented using standard UML class notation, annotated with a few additional conceptual constraints, the logical level is represented in UML, using a set of UML stereotypes, and the XML Schema itself represents the physical level. The goal of this three level design methodology is to allow conceptual level UML class models to be automatically mapped into the logical level, while minimizing redundancy and maximizing connectivity.