XML based description model as a platform for Web-based maintenance

Web technologies are gaining increased importance in automation and control systems. The choice of appropriate Web technologies depends on the use cases in the application environment. However, it is important not only to focus on one single technology, but to combine and to integrate different Web technologies within a portal. The paper discusses such a Web portal for maintenance purposes, which uses several Web technologies. It is based on a model describing the relations between topological and functional entities of the application system and the single Web technologies used. This hierarchical description model is defined in XML. The structure of this model is described and the use of description information for the realization of different functionality is shown. Special attention is paid to the security features of the solution. This requires specific description elements, ensuring access to description is limited to functional roles or user personalization. Different implementation aspects, and experiences derived from two prototype implementations are discussed