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OGC Catalog Service for the Web (CS/W): experience in NASA John D. Evans, Ph.D.

OGC Catalog Service for the Web (CS/W): experience in NASA John D. Evans, Ph.D. john.evans@nasa.gov NASA Geosciences Interoperability Office (GIO) Earth Science Applications Division -/- Global Science & Technology, Inc. Goddard Space Flight Center, Greenbelt, MD. Introduction & overview.

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OGC Catalog Service for the Web (CS/W): experience in NASA John D. Evans, Ph.D.

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  1. OGC Catalog Service for the Web (CS/W): experience in NASA John D. Evans, Ph.D. john.evans@nasa.gov NASA Geosciences Interoperability Office (GIO) Earth Science Applications Division -/- Global Science& Technology, Inc. Goddard Space Flight Center, Greenbelt, MD

  2. Introduction & overview • OGC CS/W specification: Spring 2004 • (After many iterations) • OGC ebRIM profile: Fall 2005 • NASA experimenting with CS/W since Fall 2004 • Two implementations in particular: • ECHO CS/W connector (Center for Spatial Information Science & Systems [CSISS], George Mason University) • Earth Science Gateway (NASA Geosciences Interoperability Office [GIO] & Compusult Ltd.) • Implementation experience • Insights, opportunities, and challenges

  3. GMU / CSISS experience with CS/W • Bird’s eye view - From Bai, Y., et al., 2007: Towards a Geospatial Catalogue Federation Service, Photogrammetric Engineering & Remote Sensing 73 (6), pp. 699-708

  4. GMU / CSISS experience with CS/W • Inside the Catalogue Federation Service - From Bai, Y., et al., 2007: Towards a Geospatial Catalogue Federation Service, Photogrammetric Engineering & Remote Sensing 73 (6), pp. 699-708

  5. RegistryObject ClassificationSchema Service Service Info. Model (ISO 19119) Classification ExtrinsicObject Association ServiceBindings CSWExtrinsicObject RepositoryItem …… RegistryEntry Dataset Info. Model (ISO 19115) NASA EOS Core System (ECS) Slot GMU / CSISS experience with CS/W • ebRIM model extends OGC CSW for geospatial resources • ebRIM + OGC Catalogue Service for CS/W + OGC Catalogue Service for ISO 19115/19119

  6. GMU / CSISS: CS/W bridge to ECHO • http://laits.gmu.edu:8099/ECHO9CSW2/discovery • Connects to the full, operational ECHO • Partial ECHO–ebRIM mapping. Emphasis: • CS/W core queryables (Dublin Core) • Granules (not Collections) • Performance issues: • ECHO not fully optimized for granule-level search • ECHO 8 responds to most queries from CS/W connector in under 2 minutes (used to be worse) • ECHO 9 may further improve query performance • Multiplicity of schemas poses add’l challenges • CS/W used as a “hub” for several different catalogs

  7. NASA / GIO Earth Science Gateway (ESG)

  8. Web Publishing Client OGC CSW Requests - GetCapabilities (1) - GetRecords (2) OGC CSW Transactions (3) - Insert - Update - Delete OGC Repository Extensions - GetRepositoryItem (4) - PutRepositoryItem (5) OGC WMS Servers OGC WFS Servers OGC WCS Servers Capabilities XML Document (1) External Applications/Clients Search Results (2) Service Manager Transaction Status (3) Repository Item (4) Service Registry Database (Oracle) Repository Status (3) Earth Science Gateway (ESG)Service Manager

  9. Web Publishing Client OGC CSW Requests - GetCapabilities (1) - GetRecords (2) OGC CSW Transactions (3) - Insert - Update - Delete OGC Repository Extensions - GetRepositoryItem (4) - PutRepositoryItem (5) OGC WMS Servers OGC WFS Servers OGC WCS Servers Capabilities XML Document (1) External Applications/Clients Search Results (2) Service Manager Transaction Status (3) Repository Item (4) Service Registry Database (Oracle) Repository Status (3) Earth Science Gateway (ESG)Service Manager • ESG portal uses CS/W internally for all catalog access • Search • Publish • Harvest • Public interface available for other CS/W clients • Simple HTML client can query other CS/W servers

  10. ESG in OGC Web Services Testbed 3 • Successful connections from a Refractions Research CS/W client (Nov. 2005) • Key challenge: reconciling different ebRIM representations • E.g., WMS Layer Extrinsic Object: is its ObjectType “Layer”? “WMS_Layer”? or “Data_Set”? • A guessing game; create equivalencies to fit queries coming from different clients • Changing an ebRIM type name can be a headache • Another challenge: maintaining performance • Query response slowed a lot at 100k-200k records. • Server-side workarounds: temp tables; caching; returning summaries rather than full records

  11. ESG in OGC Web Services Testbed 4 EO-1 UAV

  12. ESG: ebRIM model of OGC Web Service Service Binding ServiceBinding User Classification Classification uuid = service uuid = classified_object OffersService Service (WMS, WFS, WCS) ExtrinsicObject objectType =Layer / featureType / CoverageOfferingBrief ExtrinsicObject objectType =Layer / featureType / CoverageOfferingBrief HasFootprint ExtrinsicObject objectType = Geometry Offers HasFootprint HasContext uuid = parent ExtrinsicObject objectType = Dataset Description (Metadata Document) ExtrinsicObject objectType = Context Document (WMS only) Describes Extents uuid = classified_object Classification

  13. ESG: ebRIM model of OGC Web Service objects(WMS Layer, WFS FeatureType, WCS CoverageOffering) ExtrinsicOject objectType = LayerStyle ExtrinsicOject objectType =LayerStyle ExtrinsicOject objectType = Legend ExtrinsicOject objectType = Legend HasLegend Service (WMS, WFS, WCS) Styles Offers Classification Classification ExtrinsicObject objectType =Layer, or featureType, or CoverageOfferingBrief uuid = classified_object Externally Links ExternalLink ExternalLink Describes g.uuid = e.parent Extents ExtrinsicObject objectType = Dataset Description (Metadata Document) Extents HasFootprint ExtrinsicObject objectType = Geometry HasFootprint

  14. ESG and CS/W interoperability • ESG as CS/W server: • http://esg.gsfc.nasa.gov/wes/serviceManagerCSW/csw • Successful CS/W connections from Intergraph testbed client • Prototype CS/W connections from European Space Agency (ESA) client [http://eoportal.org] • ESG as CS/W client: • Successful CS/W connections to GMU/CSISS ECHO connector • Differences in ebRIM representations continue to be the main challenge • Conforming to CS/W is necessary but NOT sufficient for catalog interoperability

  15. CS/W opportunities & challenges • OGC CS/W interface definition is owned by no-one (consensus-based) • Support by vendors, open source, etc. • Used across many different sectors of activity • ebRIM is a promising “common ground” for catalogs • Very flexible meta-model • Growing momentum in e-business • Expect tools to manage the complexity • ebRIM: not the answer BUT a good framework for expressing the answer

  16. CS/W opportunities & challenges • CS/W & ebRIM complexity / generality • Impedes wider implementation • Impedes wider consensus on profiles? • Representing earth imagery in ebRIM: • E.g., ESA’s EO products profile (slow adoption so far) • Lots of support for product ordering • Little support for service binding • No one ebRIM representation will fit everyone • Need an imagery counterpart to Dublin Core? • NASA community could enhance catalog interoperability by defining one or more overlapping CS/W ebRIM representations

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