Enterprise specification of the NERC DataGrid

1. UK e-Science All-Hands Meeting Nottingham, 2004 Enterprise specification of theNERC DataGrid Andrew Woolf, A.Woolf@rl.ac.uk1 Ray Cramer2, Marta Gutierrez3, Kerstin Kleese van Dam1, Siva Kondapalli2, Susan Latham3, Bryan Lawrence3, Roy Lowry2, Kevin O’Neill1 1CCLRC e-Science Centre 2British Oceanographic Data Centre 3British Amospheric Data Centre

2. UK e-Science All-Hands Meeting Nottingham, 2004 Principal partners: • British Atmospheric Data Centre • British Oceanographic Data Centre • CCLRC e-Science Centre • Program for Climate Model Diagnosis and Intercomparison (LLNL), EarthSystemGrid

3. Simulations Assimilation UK e-Science All-Hands Meeting Nottingham, 2004 NERC DataGrid British Atmospheric Data Centre British Oceanographic Data Centre

4. UK e-Science All-Hands Meeting Nottingham, 2004 Outline: • Grid ‘identity crisis’ • RM-ODP • NDG Enterprise specification • Process • Summary / conclusions

5. UK e-Science All-Hands Meeting Nottingham, 2004 The Grid ‘identity crisis’ • Need to identify defining patterns of Grid computing • Formal architectural methodologies may help in abstracting these patterns • Requirements capture and analysis is starting point of any formal architecture

6. Information viewpoint Computational viewpoint Enterprise viewpoint NDG Engineering viewpoint Technology viewpoint UK e-Science All-Hands Meeting Nottingham, 2004 Reference Model for Open Distributed Processing (RM-ODP) (1) • ISO 10746-{1,2,3,4} • Formal architecture methodology for distributed systems • Viewpoints approach

7. UK e-Science All-Hands Meeting Nottingham, 2004 Reference Model for Open Distributed Processing (RM-ODP) (2) • Enterprise viewpoint • roles, activities, policies (incl. VO) • Information viewpoint • semantics of information and information processing (static, invariant, dynamic schema) • Computational viewpoint • interfaces and computational objects (cf. CORBA IDL, WSDL portTypes) • Engineering viewpoint • distribution infrastructure (e.g. web services, WSRF vs OGSI) • Technology viewpoint • choices of technology (e.g. app servers, DBMS)

8. UK e-Science All-Hands Meeting Nottingham, 2004 Reference Model for Open Distributed Processing (RM-ODP) (3) • Enterprise viewpoint: • Specification of purpose, scope and policies of system in terms of: • roles: “identifier for a behaviour” • activities: ordered sequence of actions • policies: set of obligations, permissions or prohibitions • Stakeholders must agree on these! • Structured basis for requirements capture and analysis • UML Use Cases, Collaborations, Activity Diagrams may be useful (NB: ISO/IEC 19793 “Information technology – Open distributed processing – Use of UML for ODP system specifications” developing UML profile)

9. UK e-Science All-Hands Meeting Nottingham, 2004 NDG Enterprise specification

10. UK e-Science All-Hands Meeting Nottingham, 2004 NDG Enterprise specification: Process (1) • Original plan: one major face-to-face meeting for each RM-ODP viewpoint • TOO OPTIMISTIC! • Finally: series of meetings on Enterprise specification, i.e. precisely what NDG was intended to do • Requirements refined into EV roles, activities, policies between meetings • Conflicts, assumptions identified for followup discussion

11. UK e-Science All-Hands Meeting Nottingham, 2004 NDG Enterprise specification: Process (2) • e.g.: Security • clear that role-based system was required • took considerable discussion amongst all partners to settle on details of authorisation model (see Lawrence et. al., this meeting) • e.g.: Data ‘discovery and access’ • refined into explicit activities: search  detailed metadata browse  data browse/selection  deliver data • e.g.: User ‘Workspace’ • identification of EV ‘Workspace Provider’ role raised resource-sharing issues

12. UK e-Science All-Hands Meeting Nottingham, 2004 NDG Enterprise specification: Process (3) • Needed involvement of: • resource owners, users, implementers, project collaborators • Not trivial to reach agreement on VO contracts! • Engagement with experts on current systems: • complexity of real-world datasets • legacy operational systems • deployment practicalities, etc...

13. UK e-Science All-Hands Meeting Nottingham, 2004 Summary and conclusions (1) • RM-ODP useful methodology for architecting Grids • EV provides structured approach to requirements capture and analysis (roles, activities, policies) • Need involvement of all stakeholders • Structured approach helps minimise system scoping from drifting to implementation details

14. UK e-Science All-Hands Meeting Nottingham, 2004 Summary and conclusions (2) • RM-ODP viewpoints assist detailed design, e.g.: • NDG EV activities divide naturally along metadata/data lines  core components of Information Viewpoint • NDG Computational Viewpoint interfaces strongly motivated by EV activities • Formal architecture/requirements capture for abstracting Grid patterns?