Dynamic service composition enabled by introspective agent coordination

摘要

Service composition has received much interest from many research communities. The major research efforts published to date propose the use of service orchestration to model this problem. However, the designed orchestration approaches are static since they follow a predefined plan specifying the services to be composed and their data flow, and most of them are centralized around a composition engine. Further, task decomposition is made prior to service composition, whereas it should be performed according to the available competencies. In order to overcome these limitations, we propose to model a dynamic approach for service composition. The studied approach relies on the decentralized and autonomous collaboration of a set of services whose aim is to achieve a specific goal. In our work, this goal is to satisfy requirements in software services that are freely expressed by human users (i.e. not predefined through a composition plan). We propose to enable the service collaborations through a multi-agent coordination protocol. In our model, agents offer services and are endowed with introspective capabilities, that is, they can access and reason on their state and actions at runtime. Thereby, the agents are capable of decomposing a monolithic task according to their service skills, and dynamically coordinating with their acquaintances to cover the whole task achievement. This paper presents the adaptive agent-based approach we propose for dynamic service composition, describes its architecture, specifies the underlying coordination protocol, called Composer, verifies the protocol's main properties, and validates it by unfolding an implemented scenario.