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Computational Viewpoint

Computational Viewpoint. “How the pieces fit together” Rob Atkinson Social Change Online. “Functional Decomposition”. Components What functions are needed Independent of technology, and where deployed Interfaces Protocols Query Model Response Model Encodings.

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Computational Viewpoint

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  1. Computational Viewpoint “How the pieces fit together” Rob Atkinson Social Change Online

  2. “Functional Decomposition” • Components • What functions are needed • Independent of technology, and where deployed • Interfaces • Protocols • Query Model • Response Model • Encodings

  3. Service Oriented Architectures • Components are seen as services available across a network • No code-transfer at run-time • Predictable interfaces • SEEGrid needs Open interfaces • Two models: • Request/Response (REST) • Create Virtual Object, Run, Notify (WSRF) • Common semantic challenges

  4. SEEGrid Profiles Ontology (OWL) Content classified by OGC Web Services (WFS, WCS) Viewed As Service Chains (BPEL4WS?) Domain Model (GML Application Schema) Describes Stateful Resource Handling (WSRF) Service Binding Metadata (WSDL) GML XML-Schema Messaging (SOAP) XML HTTP TCP/IP Content Protocol Stack Interfaces (Layered View)

  5. Interoperability • Network Protocol Interoperability allows basic communications between components. • Standard Interface Specifications allow client applications to execute procedures on remote systems. • Data Transport Interoperability allows transparent access to data, the sharing of spatial databases and other services regardless of the proprietary data storage format. • Semantic Interoperability refers to applications interpreting data consistently in the same manner in order to provide the intended representation of the data.

  6. Ontology Feature Type Catalog Service Metadata Dataset Metadata Persistent Bindings Real-time data Notional Architecture Registry publish find Services Processing Services Model Management Services Client Applications bind Data Access Services Coverages Models Features

  7. Dataset Metadata Dictionaries Feature Type Catalog Service Metadata Persistent Bindings Registry publish find Services Model Management Services Client Applications bind Real-time data Coverages Models Features Content Standards Notional Architecture Styling (symbology, report formats etc) Query templates (e.g. Data Products) Workflows If I have a PDF open it with Acrobat If I am a drillhole show me as a colour coded cross section Common register of custodial arrangements Notify me when tenements become available IUGS Rock Types Species Taxonomy Show me tenements that will become available soon Address Drillhole Tenements Transport Route Processing Services Address Geocoder Drillhole Database Route Planner Tenements WMS Data Access Services

  8. Adoption of Standards Suites • ISO 19000 • OGC (Implementation) • W3C – XML, Semantics • WSRF – Web Services oriented GRID computing • W3C Web services via OGC and WSRF!

  9. GT1 GT2 OGSI Started far apart in apps & tech Have been converging WSRF WSDL 2, WSDM WSDL, WS-* HTTP Grid and Web Services Grid Web The definition of WSRF means that Grid and Web communities can move forward on a common base

  10. Engineering Viewpoint “Who does what if this is to work”

  11. GRID Infrastructures

  12. Constraints and Design Goals • No solution (yet) for what best goes where • So design to allow components to be deployed anywhere • Some components need to be authoritative for interoperability to be viable • Registries (Feature Type Catalogue in particular) • Ontologies

  13. Ontologies – not so scary Authoritative terms with registered relationships • No attempt to describe everything! • Build these as stuff gets implemented • Feature Type Catalogue is an ontology

  14. Robustness and Scalability • Quality of service • Formal semantics allows: • redundancy • brokering “best” services • caching • Means: esoteric information models impact on real world performance

  15. Future Proofing • Planning for linkages with existing and emerging frameworks (e.g. OpenDAP) • Standards will undergo evolutionary change • Attention has been paid to how new standards are adopted • Extension points via ontology management • Registry the key to adoption process

  16. Adoption Process • Rationale (e.g. SEEGrid Roadmap and viewpoints) • Migration strategy if evolutionary change • Register complete suite of components required to exploit • Extend ontology to document new capabilities • Maybe create gateways, wrappers, etc to aid integration

  17. Two critical challenges • Factor data and service models so that processing services can act on data instances • Phase 1 • Establish a network accessible Feature Type Catalogue and governance processes • Solve how to serve embedded ontology and referenced vocabularies in a consistent way • Phase 2

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