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Subject: Discussion points re UML and Execution Scenarios
Hi, During the last phone conference, several issues were raised for discussion in the context of the UML diagrams provided in the the execution scenarios document [1]. Here's a list of points that were raised: (1) The UML diagrams reflect a concrete architecture rather than a reference architecture. SEE is motivated to provide a reference architecture so the data flow should not contain labels related to specific SWS ontologies (WSMO, WSML, WSMO4j) or to activities or actions that correspond to concrete architecture designs (e.g. parser and, to some extent the Communication Manager) (2) The UML diagrams should be constructed in a modular way so that reusable, composable modules can be created. For example, one module for discovery, one module for service invocation etc. (3) The activites should be represented as Goals. We agreed this before. (4) Modelling the notion of a context identifier, as the mechanism for identifying a unique instance of a running execution scenario, is not necessary in the Activity diagrams. This should be left to the design of concrete architectures. (5) Discovery (in WSMO) is now being considered in three phases - goal refinement, abstract service discovery and service discovery. How will this be reflected in the UML? (6) Is it necessary to include the communication manager necessary? (7) The dashed line used to highlight the part of the UML corresponding to the control and data flow of the execution scenario, has a specific semantics in UML activity diagrams and should be dropped. (8) The need for an execution manager activity (9) Loops are not represented e.g. there may be several service invocations in one goal-based execution Agreements: (1), (2), (3), (5), (7), (9) More discussion: (4), (6), (8), (9) ---------------------------------------------------------------- Discussion ---------------------------------------------------------------- (4) Modelling a Context Identifier My concern is that we should include in the model support for asynchonous communication. I agree that the 'context' in the UML is a bad idea as it suggests a concrete implementation. Do we make sure that the conceptual model allows for the identification of conversations between service requesters and providers and include an activity that is responsible for channeling incoming messages, as part of asynchronous conversations, to the correct conversation? (6) Communication Manager I think we need to show something that receives messages from outside SEE and 'unpacks' them into events inside SEE. Equally, I think we need something that takes events from inside SEE and 'packs' them into messages that are sent out. This is really all the CommunicationManager activity is doing in the UML at the moment. (8) Need for an Execution Manager An activity to start execution scenarios and route incoming messages to correct 'conversations'? [1] http://www.oasis-open.org//apps/org/workgroup/semantic-ex/download.php/22394/200702_SEE-Execution%20Scenarios-v08.doc Matt
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