1 UK e-Science All-Hands Meeting Nottingham, 2004 Enterprise specification of the NERC DataGrid Andrew Woolf, Ray Cramer 2, Marta Gutierrez 3, Kerstin Kleese van Dam 1, Siva Kondapalli 2, Susan Latham 3, Bryan Lawrence 3, Roy Lowry 2, Kevin O’Neill 1 1 CCLRC e-Science Centre 2 British Oceanographic Data Centre 3 British 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 UK e-Science All-Hands Meeting Nottingham, 2004 NERC DataGrid British Atmospheric Data Centre British Oceanographic Data Centre Simulations Assimilation

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

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 “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?