Dynamic Software Adaptation: Middleware for Pervasive Computing

Abstract

The many different application scenarios found in pervasive and ubiquitous computing have one aspect in common: software will be confronted with continuously changing execution environments. To guarantee seamless service, protocols, infrastructure, and applications will have to be able to adapt to changes in, e.g., networks, system configuration, available resources, varying policies, etc. In other words, adaptation will have to be a key feature of any mobile software system. In this talk I will discuss the problems encountered when designing middleware for pervasive computing and the role that software engineering could play in solving those problems. I will mostly focus on dynamic software adaptation and how it can be used to great effect to provide much more flexible software platforms. The talk will revolve around the work done on the PROSE system, a modified Java Virtual Machine that uses dynamic Aspect Oriented Programming to extend a running application with new functionality as dictated by the context where such an application runs. The extensions are code fragments that transparently adapt the underlying application. The extensions can be used to modified every aspect of the software hierarchy, e.g., they can be use both to replace a routing protocol as well as to change an application’s behavior. In the talk, I will discuss the advantage of such an approach as well as the many challenges it poses in terms of software development and maintenance, security, software modularity, and even the accepted perception of what constitutes a software application.