Structuring reflective middleware using meta-informationmanagement: The Meta-ORB approach and prototypes

Reflection is now an established technique for achieving dynamic adaptability of middleware platforms. It provides a clean and comprehensive way to access the internals of a platform implementation, allowing its customisation in order to achieve the best performance and adequacy under given operation environments and user requirements. In addition, the use of a runtime component model for the design of the internal platform structure facilitates the identification of the elements to be adapted, as all platform aspects are built in terms of components. The major limitation of this approach, however, is related to the multitude of aspects that make up a middleware platform, together with the requirement of keeping platform consistency after adaptations take place. This paper presents the results of ongoing research contributing to reduce this limitation. The approach is based on the use of a common meta-model, together with meta-information techniques to provide a uniform way to specify and manipulate platform configurations. Both platform configuration and runtime adaptation are always specified using a small number of building blocks defined in the meta-model. The paper also describes the overall architecture of the Meta-ORB platform, which demonstrates this approach, and presents its two implementations: a proof-of-concept prototype written in Python, and a Java-based implementation aimed at supporting mobile devices. The results are also evaluated from a quantitative perspective, according to the requirements of multimedia applications, one of the major areas of application of reflective middleware.