The XML family of standards makes possible the next logical step in the evolution of software from more procedural to more declarative approaches. With a declarative approach, an application developer specifies what data transformations should occur, rather than how each transformation should be performed. This presentation will describe an approach to application design and development that makes maximal use of this concept, seeing the application as a series of transformations (specified using XSLT) between different information structures (specified using XML).

The generic information structures developed by the recently completed European XML/EDI Pilot Project will be described, and prototype applications built on the basis of them will be demonstrated. These prototypes will show how powerful, multi-lingual, configurable, distributed software applications can be built out of simple reusable standards-based components.

The roles of XPath, XLink and XML Schema in the specification of such applications will be discussed, and a case will be made for the development of an XML "Action Language" which, once the logical structure of an application has been defined, will serve to fire the process and make the application run in real time. The XML Action Language developed by the European XML/EDI Pilot Project will be described, and its use in driving the prototype applications will be explained.