Katias 28 Dimensions of discovery 1.Direction: push vs pull In UDDI provider pushes, requester pulls In P2P provider pulls, requester pushes 2.Amount Info in adv: capabilities vs parameters Is there any discovery service that makes this difference? 3.Action for advertisement: broadcasting vs retaining P2P does broadcasting UDDI does retaining 4.Browsing MA DB? Yes vs no UDDI supports persistent queries 5.Amount Info in request: capability only vs parameters Is there any discovery service that makes this difference? 6.Does MA mediate transaction? Broker vs registry Since some of the combinations are irrelevant there are 28 possible MA
Importance of Semantics Goal Abstraction to capabilities Capability Description Match Advertisement List of Providers Selection Potential Providers Enactment Store Request The transformation should preserve the semantics of the query: it should not identify capabilities do not lead to the satisfaction of the goal Ask Mike Huhns Matching requires the recognition of whether the required capabilities are similar enough to the requested capabilities, ie the services that they describe (their meaning) provide similar functionalities Selection requires matching of own requirements visa vie the requirements of the providers and the functionality that they provide. The services selected are the one that provide the closest match.