1. Abstraction Layers Why do we need them? –Protection against change Where in the hourglass do we put them? –Computer Scientist perspective Expose low-level services Use SOAP as a wire protocol? –Working Scientist perspective Want high-level services Use C/C++/Java APIs Opaque Service & Interaction Handles

2. What Services / Abstractions do we need? Look at some projects: –CLRC e-Science Centre –AstroGrid –MyGrid –ICENI –OGSA

3. CLRC e-Science Centre Single sign-on authentication Security service Authorisation Additional user services (including local user management) Resource discovery service Workspace creation service 3rd party file transfer facility XML parser service Query generation Replication Data source discovery Results collation Dynamic resource monitoring Event handling services Messaging service Job submission Job monitoring Visualisation Computational steering Thesaurus service Ontology service.

4. AstroGrid VO=Virtual Observatory

5. MyGrid – Architecture

6. MyGrid Services User Agent & Repository Notification Workflow: Personalisation, Resolution, Enactment & Serialisation Databases & Distributed Query Job Scheduling & Resource Management Information Extraction Authentication Service Directory User, Group & Roles Directory Workflow Provenance & Repository Ontologies – Service function & metadata

7. ICENI Low-level services –Computational –Storage –Software –Networking High-level services –Application composition to define workflow –Scheduling (mapping components to resources) –Throughput (resource brokering)

8. OGSA (17/2/02) Is a Grid Service also a Web Service? –YES as it has ports (described in WSDL) for: Grid Service (Introspection & termination) Notification Source & Sink Registration of Grid Service Handles Service creation (factory) Primary Key (map key to GSH) Mapping (map GSH to GSR) –BUT can only be deployed in an OSGA compatible hosting environment Is a Web Service also a Grid Service? –NO as it misses out on the extra capability –BUT can be deployed within an OGSA environment

9. OGSA Services Low-level services –Execution, file transfer & service meta-data (?) Higher-level services –Distributed Data Management –Work flow –Auditing –Instrumentation & monitoring –Problem determination (e.g. dump, trace & log) –Security protocol mapping

10. Common Requirements? Low-level: –Security –Execution –Database Access –Data movement –Service Management High-level: –Workflow management (Scheduling) –Usage & Access Policy –Notification (Events & Messaging)