From Agents and Plugins to Plugin-Agents, Concepts for Flexible Architectures

Flexibility in software systems is needed to allow adaption to increasing demands of users. To ease the development of flexible architectures several approaches are used, which often differ already on the conceptual grounds. Two of these paradigms are characterized by the strong underlying metaphors plugins and agents. Plugins emphasize on an extension relation between pairs of components where each component participates in a clearly specified role. Agents have a wide variety of attributes, such as mobility, autonomy, adaptability and pro-activeness. The general relationship of agents is that of peers mutually offering and using their services - higher organizational abstractions have to be implemented based on this service-oriented view. This paper proposes to conjoin both paradigms of multi-agent systems and plugin systems, leading to the concept of a plugin-agent. First, we discuss characteristics of both concepts. The discussion clearly shows that agents and extensible components have structural similarities. This follows the combination of both concepts into the new concept of the plugin-agent. The approach presented in this paper is unique as it handles both concepts on the same architectural level - to our knowledge, all other existing combinations of agents and plugins use one of the concepts to model or implement the other.