Separation of concerns in hybrid component and agent systems

Modularising requirements is a classic problem of software engineering; concerns often overlap, requiring multiple dimensions of decomposition to achieve separation. Whenever complete modularity is unachievable, it is important to provide principled approaches to the decoupling of concerns. To this end, this paper discusses the Socially Situated Agent Architecture (SoSAA) - a complete construction methodology, which leverages existing well established research and associated methodologies and frameworks in both the Agent-oriented and Component-based Software Engineering domains. As a software framework, SoSAA is primarily intended to serve as a foundation on which to build agent based applications by promoting separation of concerns in the development of open, heterogeneous, adaptive and distributed systems. While previous work has discussed the design rationale for SoSAA and illustrated its application to the construction of multiagent systems, this paper focuses on the separation of concerns issue. It highlights concerns typically addressed in the development of distributed systems, such as adaptation, concurrency, fault-tolerance. It analyses how a hybrid agent/component integration approach can improve the separation of these concerns by leveraging modularity constructs already available in agent and component systems, and sets clear guidelines on where the different concerns must be addressed within the overall architecture. Finally, this paper provides a first evaluation of the application of our framework by applying well-known metrics to a distributed information retrieval case study, and by discussing how this initial results can be projected to a typical multiagent application developed with the same hybrid approach.