The introduction of mobile code in the pervasive computing environment provides a good opportunity for research in ways to enhance execution flexibility. We note that current mobile code is too heavyweight and not adaptive enough to be used in pervasive computing where devices are resourcelimited and heterogeneity is the norm. In this paper, we propose a new lightweight, component-based mobile agent system that can adapt to diverse devices and features resource saving as one of its aims. The system supports strong mobility of mobile code, which is a prerequisite for achieving system flexibility and good performance. The system discretize the transmission of code and execution states and relies on a scheme called state-on-demand (SOD) for the execution of the mobile code. We provide performance results to demonstrate the effectiveness of the SOD scheme.

The Æ�-calculus, a new calculus based on the �-calculus, is a model for mobile distributed computation. The Æ�-calculus can be used to specify applications, in order to reason about their security and correctness properties. The Æ � primitives have been been implemented as a Java API. The implementation in Java provides a means of bridging the gap between application specification and implementation. 1

acceptée sur proposition du jury: Prof. A. Wegmann, président du jury Prof. M. Odersky, directeur de thèse