Dynamic software architectures

Sammanfattning:  Softwarearchitecture is a software engineering discipline that providesnotations and processes for high-level partitioning of systems'responsibilities early in the software design process. This thesisis concerned with a specific subclass of systems, systems with adynamic software architecture. They have practical applications invarious domains such as high-availability systems and ubiquitouscomputing.In a dynamic software architecture, the set of architecturalelements and the configuration of these elements may change atrun-time. These modifications are motivated by changed systemrequirements or by changed execution environments. The implicationsof change events may be the addition of new functionality orre-configuration to meet new Quality of Service requirements.This thesis investigates new modeling and implementation techniquesfor dynamic software architectures. The field of DynamicArchitecture is surveyed and a common ground defined. We introducenew concepts and techniques that simplify understanding, modeling,and implementation of systems with a dynamic architecture, withthis common ground as our starting point. In addition, weinvestigate practical use and reuse of quality implementations,where a dynamic software architecture is a fundamental designprinciple.The main contributions are a taxonomy, a classification, and a setof architectural patterns for dynamic software architecture. Thetaxonomy and classification support analysis, while the patternsaffect design and implementation work directly. The investigationof practical applications of dynamic architectures identifiesseveral issues concerned with use and reuse, and discussesalternatives and solutions where possible.The results are based on surveys, case studies, and exploratorydevelopment of dynamic software architectures in differentapplication domains using several approaches. The taxonomy,classification and architecture patterns are evaluated throughseveral experimental prototypes, among others, a high-performancescientific computing platform.