1. SeLeNe - Architecture George Samaras Kyriakos Karenos Larnaca – April 2003 THE UNIVERSITY OF CYPRUS

2. SeLeNe – University of Cyprus Presentation Preview Introduction – Service-based Approach SeLeNe Proposed Services Authorities Service Availability Simple Scenarios Alternatives – C-B-P model

3. SeLeNe – University of Cyprus Introduction Service-based Approach –The Grid: Architecture made up of services –Semantic Grid for eScience –Using Services: Examples Tools –JXTA (p2p) –Globus (grid) –Web Services –RMI, CORBA

4. SeLeNe – University of Cyprus Proposed Services (I) Classification: Core\Appended Relevance to OGSA and Semantic Grid Trail Management, Authoring, Collaboration Caching, Search, Replication Access,Information, Integration Registration, Security, Communication Storage Application Fabric Resource Connectivity Collective

5. SeLeNe – University of Cyprus Proposed Services (II) Core Services –Information Service LO Metadata Services –Storage Service Content (LOs) Metadata physical files Indices (known sites) –Communication Service Available Protocols (TCP\IP,…)

6. SeLeNe – University of Cyprus Proposed Services (III) Appended Services –Registration –Search Uses the information Service Schema heterogeneity issues – Clusters? –Access Allow local and remote access to heterogeneous LOs via a common API –Caching Local and Remote Content, Service and Message caching

7. SeLeNe – University of Cyprus Proposed Services (IV) Appended Services –Replication File copying and Transferring (Access Serv) Single Owner Update Propagation Object Lookup: logical-to-physical –Security On local data Third party –Collaboration Possibly available Services (Blackboards, Message Boards) managed by high level service

8. SeLeNe – University of Cyprus Proposed Services (V) Appended Services –Integration Service Transparent integration mechanism –Authoring Create and visualize –Trail Management Knowledge Layer The most difficult to design at this point (requires lower level services)

9. SeLeNe – University of Cyprus Authorities Super-peer like Reliable service provision Static participation Provide persistent services including: Collaboration, Caching, Registration, Integration… Roles: –Mediators (handle ontology diversion) –Coordinators (e.g. maintain Collaboration state, manage Integration process) –Third party (security, pricing)

10. SeLeNe – University of Cyprus Service Availability Basic services are made core. Reliable sites (authorities) provide popular/demanding services Service replication Break services to smaller components Remote service starting to save resources Predictable service shutdown

11. SeLeNe – University of Cyprus Example (I) A B C D E

12. SeLeNe – University of Cyprus Example (II) ‘C’ Uses Search service identifies sites ‘A’ and ‘D’ Integration service at site ‘B’ used user-view Access service at site ‘A’ Saved at the local cache Replication Service at ‘B’: Replicate locally a part Information service: new interconnections/ relationships between LOs. an individual author creating a new derived LO and its associated metadata from other LOs ACore, Search, Access, BCore, Collaboration, Registration, Integration, Search, Replication CCore, Search, Authoring, Cache DCore, Search

13. SeLeNe – University of Cyprus Alternatives (I) Maintain the Service-based focus Create sets of services “Consumer” services, “Brokering” services and “Producer” services Two different Setups presented later

14. SeLeNe – University of Cyprus Alternatives (II) Views to the C-B-P architecture Grid Like Super-Peer like SeLeNe Brokers Producers Consumers Producer Consumer Broker

15. SeLeNe – University of Cyprus Alternatives (II) Setup 1 –Define strict roles to each site Producer Services: Repositories Consumer Services: Client Brokering Services: Brokers Analogy to Database Users Repositories Brokers Clients

16. SeLeNe – University of Cyprus Alternatives (III) Setup 2 –Allow Consumer\Producer services to be co- located at sites i.e. LOs stored at any site –May require site collaboration –Local Services (more independent) Brokers Consumer Producer Consumer\Producer

17. SeLeNe – University of Cyprus Comparison (I) Distribution of Services –Pure Grid: “Heavy”, weight on servers –Grid\P2P: more flexible, site of various resources –C-B-P: Somewhere in the Middle Dynamic –Pure Grid: Low. Server site must remain up and be static but highly available –Grid\P2P and C-B-P: highly dynamic but no quality of service – can be dealt with! –Dynamic nature Vs Availability Trade-offs

18. SeLeNe – University of Cyprus Comparison (II) Managerial Ease –Pure Grid and C-B-P: Highly Manageable- strict service specification –P2P\Grid: Difficult to manage, independent sites. More supported services (powerful) - autonomy Vs Light but dependent

19. SeLeNe – University of Cyprus