OGC Catalog Service for the Web CSW experience
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 ● OGC CS/W specification: Spring 2004 – (After many iterations) ● OGC eb. RIM 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
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
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
GMU / CSISS experience with CS/W ● ● eb. RIM model extends OGC CSW for geospatial resources eb. RIM + OGC Catalogue Service for CS/W + OGC Catalogue Service for ISO 19115/19119 Registry. Object Classification Association Service. Bindings …… Registry. Entry Classification. Schema Service Info. Model (ISO 19119) Extrinsic. Object CSWExtrinsic. Object Repository. Item Dataset Info. Model (ISO 19115) NASA EOS Core System (ECS) Slot
GMU / CSISS: CS/W bridge to ECHO ● http: //laits. gmu. edu: 8099/ECHO 9 CSW 2/discovery ● Connects to the full, operational ECHO ● Partial ECHO–eb. RIM mapping. Emphasis: – – ● Performance issues: – – – ● CS/W core queryables (Dublin Core) Granules (not Collections) 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
NASA / GIO Earth Science Gateway (ESG)
Earth Science Gateway (ESG) Service Manager OGC CSW Requests - Get. Capabilities (1) - Get. Records (2) Web Publishing Client OGC CSW Transactions (3) - Insert - Update - Delete OGC WFS Servers OGC Repository Extensions - Get. Repository. Item (4) - Put. Repository. Item (5) OGC WCS Servers Capabilities XML Document (1) External Applications/Clients Search Results (2) Transaction Status (3) OGC WMS Servers Service Manager Repository Item (4) Repository Status (3) Service Registry Database (Oracle)
Earth Science Gateway (ESG) Service Manager ● ESG portal uses CS/W internally for all. Web Publishing catalog access Client OGC CSW Requests - Get. Capabilities (1) - Get. Records (2) – Search – Publish – Harvest OGC WMS Servers OGC CSW Transactions (3) - Insert - Update - Delete OGC WFS Servers OGC Repository Extensions - Get. Repository. Item (4) - Put. Repository. Item (5) ● Capabilities XML Public interface available for other CS/W clients Document (1) ● Search query other CS/W servers Simple HTML client Results can External (2) Applications/Clients Transaction Status (3) OGC WCS Servers Service Manager Repository Item (4) Repository Status (3) Service Registry Database (Oracle)
ESG in OGC Web Services Testbed 3 ● ● Successful connections from a Refractions Research CS/W client (Nov. 2005) Key challenge: reconciling different eb. RIM representations – – – ● E. g. , WMS Layer Extrinsic Object: is its Object. Type “Layer”? “WMS_Layer”? or “Data_Set”? A guessing game; create equivalencies to fit queries coming from different clients Changing an eb. RIM type name can be a headache Another challenge: maintaining performance – – Query response slowed a lot at 100 k-200 k records. Server-side workarounds: temp tables; caching; returning summaries rather than full records
ESG in OGC Web Services Testbed 4 EO-1 UAV
ESG: eb. RIM model of OGC Web Service Binding User Classification uuid = service Offers. Service Has. Footprint Service Extrinsic. Object (WMS, WFS, WCS) Extrinsic. Object Offers object. Type = Geometry uuid = parent Has. Footprint object. Type = Context Document (WMS only) object. Type== Layer/ /feature. Type/ / Coverage. Offering. Brief Has. Context Extrinsic. Object Extents uuid = classified_object Describes Extrinsic. Object object. Type = Dataset Description (Metadata Document) uuid = classified_object Classification
ESG: eb. RIM model of OGC Web Service objects (WMS Layer, WFS Feature. Type, WCS Coverage. Offering) Extrinsic. Oject object. Type = = Layer. Style Service Has. Legend (WMS, WFS, WCS) Offers Externally Links External. Link Extents Extrinsic. Oject object. Type = Legend Styles Classification Extrinsic. Object object. Type = Layer, or feature. Type, or Coverage. Offering. Brief uuid = classified_object Describes g. uuid = e. parent Has. Footprint Extrinsic. Object object. Type = Geometry Extrinsic. Object object. Type = Dataset Description (Metadata Document) Has. Footprint
ESG and CS/W interoperability ● ESG as CS/W server: – – – ● ESG as CS/W client: – ● http: //esg. gsfc. nasa. gov/wes/service. Manager. CSW/csw Successful CS/W connections from Intergraph testbed client Prototype CS/W connections from European Space Agency (ESA) client [http: //eoportal. org] Successful CS/W connections to GMU/CSISS ECHO connector Differences in eb. RIM representations continue to be the main challenge – Conforming to CS/W is necessary but NOT sufficient for catalog interoperability
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 eb. RIM is a promising “common ground” for catalogs – Very flexible meta-model – Growing momentum in e-business ● ● Expect tools to manage the complexity eb. RIM: not the answer BUT a good framework for expressing the answer
CS/W opportunities & challenges ● ● CS/W & eb. RIM complexity / generality – Impedes wider implementation – Impedes wider consensus on profiles? Representing earth imagery in eb. RIM: – ● E. g. , ESA’s EO products profile (slow adoption so far) ● Lots of support for product ordering ● Little support for service binding – No one eb. RIM 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 eb. RIM representations
- Slides: 16