Affiliations: Alma Mater Studiorum – Università di
Bologna, Italy
Note: [] Corresponding author: Andrea Omicini, DEIS, Università di
Bologna, via Venezia 52, 47023 Cesena, Italy. Tel.: +39 0547 3 39220; Fax: +39
0547 3 39219; E-mail: [email protected]
Abstract: Governing interaction, and in particular intra-system,
inter-component interaction, is essential in the engineering of non-trivial
multi-component systems. This also holds for Web-based systems à today the
most relevant and widespread sort of distributed software system. Agent models
and technologies are among the most promising approaches to the engineering of
Web applications. In particular, agent coordination infrastructures aim at
harnessing the complexity of interaction within MASs (multiagent systems), by
providing agents and engineers with coordination artifacts, which shape
agent environment by governing agent-to-agent and agent-to-environment
interactions. Horizontal integration of Web infrastructure with agent
coordination infrastructure is then a key issue in the engineering of
agent-based Web applications. In this paper, we focus on the problem of
time: time is essential in a large number of Web coordination scenarios and
patterns – involving timeouts, obligations, commitments, etc. Along this line,
we first discuss the notion of coordination artifact and its relation to agent
environment. Then we discuss a notion of timed environment for Web
agents, and show how it can be enforced through suitably-extended timed
coordination artifacts. In particular, we adopt TuCSoN tuple centres (along
with the ReSpecT language for programming them) as our concrete
representatives for coordination artifacts, and show how they can be extended
to catch with time, and to support the definition and enforcement of time-aware
coordination policies. A Web-based agent workflow is finally presented as a
case study, and used to demonstrate the expressiveness of the ReSpecT
language to model timed coordination primitives and laws.
