LEAD++: An Object-Oriented Re ective Language for Dynamically Adaptable Software

A system has dynamic adaptability if it can adapt itself to dynamically changing runtime environments. As open-ended distributed systems and mobile computing systems have spread widely, the need for software with dynamic adaptability increases. We propose a model of software with dynamic adaptability and the object-oriented reective language LEAD++ based on the model. The basic idea is that we introduce the mechanism which changes procedure invocations dynamically depending on the states of runtime environments. The mechanism forms a meta-level architecture, and realizes dynamic adaptability in reective way. LEAD++ provides the mechanism as a language functionality. We are currently implementing a prototype of LEAD++ as a preprocessor of Java. Using LEAD++, we can systematically describe dynamically adaptable applets, mobile objects, etc.