Adaptive Operating System Design using Reflection

Flexibility to adapt to di erent applications is a key requirement of modern operating systems. We have explored the use of meta-objects and re ection as a means to write adaptable system software. This paper discusses the Apertos operating system that uses these techniques. It outlines how meta-objects help to support exibility and how we have implemented the concepts, and gives some performance gures. 1 Flexibility in operating systems Recent trends in networking, multi-media and mobile computing have placed new requirements on the exibility and adaptability of existing operating systems. It is increasingly recognised that existing OS architectures are not su ciently exible to meet these demands. As such there is signi cant interest in building more exible, or adaptive operating systems. It is our belief that this trend represents one of the most important hot topics in the OS research community. We can categorise exibility in work to date as follows: exibility in the way we combine the components of the system at build time, exibility in the way the systems adapts to application needs and exibility in the way the system and its interfaces evolve over time. There has been much work in the OS community that aims to support these exibility requirements. However we argue that much of this work lacks a consistent framework, ie. the mechanisms adopted have been applied to selected areas, and di erent mechanisms have been used in di erent parts of the system. The Apertos system is an operating system design that uses the language community ideas of metaobject programming and re ection to support an open OS architecture in which all aspects of the system are exible. This paper brie y outlines recent work on extending system exibility and then discusses the Apertos system and its use of a meta-object protocol.