A Survey of Coordination Middleware for XML-centric Applications

This paper focuses on coordination middleware for distributed applications based on active documents and XML technologies. First, the paper introduces the main concepts underlying active documents and XML, and identifies the strict relations between active documents and mobile agents (“document agents”). Then, the paper goes into details about the problem of defining a suitable middleware architecture to support coordination activities in applications including active documents and mobile agents, by specifically focusing on the role played by XML technologies in that context. A simple taxonomy is introduced to characterise coordination middleware architectures depending on the way they exploit XML documents in supporting coordination. The characteristics of several middleware infrastructures are then surveyed and evaluated, also with the help of a simple example scenario in the area of distributed workflow management. This analysis enables us to identify the advantages and the shortcomings of the different approaches, and the basic requirements of a middleware for XML-centric applications.