1 uk e-science all-hands meeting nottingham, 2004 enterprise specification of the nerc datagrid...
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UK e-Science All-Hands MeetingNottingham, 2004
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Enterprise specification of theNERC DataGrid
Andrew Woolf, [email protected]
Ray Cramer2, Marta Gutierrez3, Kerstin Kleese van Dam1, Siva Kondapalli2, Susan Latham3, Bryan Lawrence3, Roy
Lowry2, Kevin O’Neill1
1CCLRC e-Science Centre2British Oceanographic Data Centre
3British Amospheric Data Centre
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Principal partners:British Atmospheric Data Centre
British Oceanographic Data Centre
CCLRC e-Science Centre
Program for Climate Model Diagnosis and Intercomparison (LLNL), EarthSystemGrid
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NERC DataGrid
British Atmospheric Data Centre
British Oceanographic Data Centre
Simulations
Assimilation
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Outline:• Grid ‘identity crisis’
• RM-ODP
• NDG Enterprise specification
• Process
• Summary / conclusions
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The Grid ‘identity crisis’
The GRI D – Hype or Reality?Roger Barlow
Manchester and Stanford University
Symposium in celebration of J ohn Vincent AtanasoffI owa State University, 31st October 2003
What is the Grid?Problems and Tools that solve themProgressProspects
• 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
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Reference Model for Open Distributed Processing (RM-ODP) (1)
• ISO 10746-{1,2,3,4}• Formal architecture methodology for distributed
systems• Viewpoints approach
Enterpriseviewpoint
NDG
Informationviewpoint
Computationalviewpoint
Technologyviewpoint
Engineeringviewpoint
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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)
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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)
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NDG Enterprise specification
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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
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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
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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...
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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
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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?