Querying service contracts

Considering a broad definition for service contracts (beyond web services and software, e.g. airlinetickets and insurance policies), we tackle the challenges of building a high performance broker inwhich contracts are both specified and queried through their temporal behavior. The temporaldimension, in conjunction with traditional relational attributes, enables our system to better addressdifficulties arising from the great deal of information regarding the temporal interaction of the variousevents cited in contracts (e.g. ”No refunds are allowed after a reschedule of the flight, which can berequested only before any flight leg has been used”). On the other hand, querying big repositories oftemporal specifications poses many interesting challenges. In this paper, we introduce two distinctand complementary optimization techniques that enable our system to scale the evaluation of a noveland theoretically sound notion of permission of a temporal property by a service contract. Our notionof permission is inspired by previous work on model checking but, given the specific characteristic ofour problem, does not reduce to it. We evaluate experimentally our implementation, showing thatit scales well with both the number and the complexity of the contracts.