TImed Coordination Artifacts with ReSpecT

Environment-based approaches to Multi-Agent Systems (MAS) advocate the use of abstractions mediating the interaction between agents, providing an alternative viewpoint to the standard speech-act-based approach. A remarkable example is rooted in the notion of coordination artifact: embodied entities provided by the MAS infrastructure to automate a specific coordination task, and featuring peculiar engineering properties such as encapsulation, predictability, inspectability and malleability. An example technology supporting this scenario is TuCSoN, where coordination artifacts are built as tuple centres programmed with the ReSpecT logic language. In most application scenarios characterised by a high degree of openness and dynamism, coordination tasks need to be time-dependent so as to be able to specify and guarantee necessary levels of liveness and of quality of service. Moreover, temporal properties are also fundamental for intercepting violations in the agent-artifact contract, which is at the root of the engineering approach underlining coordination artifacts. Accordingly, in this paper we introduce an extension to the ReSpecT language allowing to define timed coordination artifacts in the TuCSoN infrastructure. This is achieved by adding the management of trap events, fired and intercepting using the same mechanism currently used by ReSpecT to handle communication events, thus in a uniform and coherent way. Examples are provided to show the expressiveness of the language to model temporal-based coordination tasks.