Experiences in integration and reuse of CORBA-interfaced software with directory services and Web services

Distributed legacy systems often provide complex and extensive interfaces. Even if these interfaces consist of standardized CORBA (common object request broker architecture) definitions, they still require too much in-depth knowledge for easy third party integration of small additional components, which could in principle be achieved with just a small subset of the interfaces´ functionality. Therefore, we used XML (extensible markup language) to tag particular parts of the middleware´s interface for easy third party access with simple protocols, like the lightweight directory access protocol for directory services, or the simple object access protocol for Web services. The respective requests are then dynamically mapped to suitable CORBA operation invocations. We provide the mapping schema and the software architecture for a real-life example. The XML tagging has proven to be a powerful means of abstraction, which allows for robust and easy but flexible access to complex and even continuously changing distributed middleware. Therefore, XML plays a major role for heterogeneous interface descriptions, where middleware technologies and simple access services will coexist in the future.