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Page 1© Crown copyright 2006 Registry technology & case study implementation J. Tandy, D. Thomas - November 2006.

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Presentation on theme: "Page 1© Crown copyright 2006 Registry technology & case study implementation J. Tandy, D. Thomas - November 2006."— Presentation transcript:

1 Page 1© Crown copyright 2006 Registry technology & case study implementation J. Tandy, D. Thomas - November 2006

2 Page 2© Crown copyright 2006 What is a registry? - definition  A registry is an information system on which a register is maintained  A register is a controlled list of information (ISO19135 Geographic Information – procedures for item registration) Registry

3 Page 3© Crown copyright 2006 Information hub  When combined with a portal, the registry acts as a hub within the distributed data infrastructure … Registry Portal Information resources  Providing an aggregated view of content from numerous, heterogeneous information resources

4 Page 4© Crown copyright 2006 Propagation of standards  For content to aggregated into a single view, information resources (or services that expose them) must adhere to standards –  WMO Core Metadata Profile  ISO 191xx  etc.  Publication of standards factored into simple modules promotes sharing, re-use & (eventually) interoperability Registry Portal Information models Data standards Best practice Standards coordinator

5 Page 5© Crown copyright 2006 Focal-point  Registry provides focal-point: Registry Portal  Propagating best practice, standards and governance  Discovering and exploiting information resources and services Discovery metadata for content offerings Service metadata for binding to information resources Discovery metadata Search & browse by exposing discovery metadata Service invocation Service metadata Data

6 Page 6© Crown copyright 2006 ebXML Registry-Repository  ebXML Registry-Repository provides generic content and metadata management services  Multiple components:  Query manager & lifecycle manager  Authentication & authorization  Metadata registry  Content repository RepositoryItems: XML, documents, images, etc. … RegistryObjects: describe RepositoryItems (metadata) ebXML RR Metadata registry Content repository

7 Page 7© Crown copyright 2006 ebXML Registry Information Model (ebRIM)  ebRIM (ISO ) is the information model for the metadata registry  Core information model  Association information model  Classification information model  Provenance information model  Service information model  Event information model  Cooperating Registries info. model  Access Control information model  Extensibility is most significant benefit Identifiable RegistryObject Slot ExtrinsicObject RegistryPackage Association Classification Service AdhocQuery Subscription … … (Incomplete)

8 Page 8© Crown copyright 2006 OGC Catalogue Services for Web (CSW)  ebXML-RR exposes query & lifecycle management functionality via Registry Services (ebXML-RS)  As specified, ebXML does not support geospatial or temporal queries  Open Geospatial Consortium have published a set of profiles for ebRIM based on their Catalogue standard*:  protocol binding  recommended set of RegistryObject fields based on Dublin Core  spatio-temporal discovery capability (* ISO profile also published) ebXML RR Metadata registry Content repository OGC CSW interface

9 Page 9© Crown copyright 2006 Oceans Portal – case study  The Oceans Portal provides key infrastructure components to support online discovery and access to marine information within Australian jurisdictions  It comprises of the following main components:  A portal application (multiple entry-points to catalogue)  A catalogue (registry – OGC CSW profile of ebRIM)  Interoperable data and services (content offerings)  Online resources exposed by web-based portal, ranging from simple documents and web links through to complex, queryable datastores

10 Page 10© Crown copyright 2006 Registering content in the Oceans Portal ebXML RR Metadata registry Content repository OGC CSW interface Data provider Registry client Publish static ‘metadata’ records via registry client: harvest control file service bindings custodian classification(s) * finder * binder * Where possible, the data provider is encouraged to re-use existing metadata * optional Volatile metadata harvested directly from service as specified by ‘harvest control file’ – ensures content offering is valid! Data access service

11 Page 11© Crown copyright 2006 The discovery model  The portal provides a general purpose discovery model that will work for all types of resources, from large structured databases supporting many different queries to single documents.  Discovery is based on the following principles:  Iterative, incremental filtering of results based on refinement of search parameters  Concurrent browse and search  User-friendly exposure of underlying information model, clear presentation of schemes used to classify content  Ability to create re-usable ‘search links’; e.g. for publication on homepage

12 Page 12© Crown copyright 2006 Search ‘axes’ – GCMD topic & Species tax.

13 Page 13© Crown copyright 2006 Search ‘axes’ – spatial extent

14 Page 14© Crown copyright 2006 Search ‘axes’ – searchable metadata ebXML RR Metadata registry Content repository OGC CSW interface Classification Controlled vocabularies Searchable metadata elements The ‘finder’ is a query model for accessing content in the registry

15 Page 15© Crown copyright 2006 Example – Sea Surface Temperature (1) Search for ‘temperature’ within the topic browser … Select ‘Sea Surface Temperature’ from results set …

16 Page 16© Crown copyright 2006 Example – Sea Surface Temperature (2) Select a known area; ‘Great Barrier Reef’ … could enter coordinates … But, I want to refine my search further …

17 Page 17© Crown copyright 2006 Example – Sea Surface Temperature (3) Select ‘most recent SST analysis’ from drop-down list … Only one result set … ask for ‘more info’ then ‘add to map’

18 Page 18© Crown copyright 2006 The data access model  Having discovered content of interest, a user is able to ‘bind’ to the content …  A ‘binder’ is a Data Access Query Model (DAQM) used to define and present binding options:  service location  protocol  message structure  permissible / appropriate values  Where possible, terms from the discovery phase (finder) are propagated through to the binder, ensuring simple, intuitive transition from discovery to access  Default binders include: WMS basic, WMS time, WFS, Document, Weblink and Event

19 Page 19© Crown copyright 2006 Example – Sea Surface Temperature (4) Data access request processed ‘transparently’ … search parameters used to complete the service invocation – WMS-basic in this case

20 Page 20© Crown copyright 2006 Conclusions  The Oceans Portal provides an excellent example of how an ebRIM registry can be used to underpin a spatial data infrastructure.  The capabilities provided overlap significantly with those required for WIS.  Oceans Portal is an extensible, flexible infrastructure that can grow and evolve as new requirements, content and services emerge.  The Oceans Portal is a strong candidate for use as the basis of a GISC-registry, providing proven capability whilst decoupling the registry & discovery portals from the underlying data services themselves.

21 Page 21© Crown copyright 2006 Questions & Answers

22 Page 22© Crown copyright 2006 THREDDS THematic Realtime Environmental Distributed Data Services  Offers significant utility for exposing ‘earth-science’ datasets  Questionable extensibility:  THREDDS ‘discovery’ metadata record (similar to ebRIM RegistryObject) lacks extension points to add custom fields  Lack of ability to browse (& realise) non-hierarchical relationships between entities; although noted that hierarchies are user / community defined & a dataset may appear in (be classified by) more than one hierarchy  Limited bindings to data access services  The end of THREDDS? No … THREDDS catalogues could be used to expose information resources that are aggregated within a principal ebRIM registry  THREDDS and ebRIM are seen to be complimentary


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