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DSTT Report OGC Services

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  1. DSTT ReportOGC & GRID Services DSTT ReportOGC Services Allan Doyle NASA/II May 8, 2002

  2. “If you don’t understand first off and it makes your mind go numb, you’re safe to ignore it, it will never work” • Dave Winer at InfoWorld Next Generation Web Services Conference, January 2002

  3. Info OGC Services http://www.intl-interfaces.net/servicemodel GRID Services http://www.globus.org/ogsa/

  4. Services Time Line Basic Service Model Discussion Paper OpenGIS® Catalog Interface Implementation Specification 1.1 OpenGIS® Catalog Interface Implementation Specification 1.0 Web Registry Services Discussion Paper OpenGIS® Abstract Spec Topic 12 - The OpenGIS Service Architecture OGC Architecture SIG WWW Mapping SIG WMT-1 ServicemodelAd Hoc IP2000 (WMT-2) IP2001 (OWS-1) OWS 1.2 J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D 1999 2000 2001 2002 GCMD (SERFs) NASA ECHO CEOS WTF-GOFC CEOS WTF (??) Google ebXML Industry Microsoft .NET UDDI Grid Services

  5. Client Application <service name=WMS> <layer name=“FirePoint”> … <dataURL=ftp://…> GetMap WCS WFS WMS Feature Data Store Coverage Data Store Map Data Store Technical ChallengesData vs. Services • Search for Services first • Decision support community view ? Develop metadata and discovery mechanisms that can support both service-centric and data-centric modes. • Search for Data first • Science community view ? GetFeature GetCoverage Service Catalog Fusion Services Data Catalog Geocode GeoParse GeoLink <dataset name=MODIS> <Online_Resource name=“WMS”> http://foo.org/wms.cgi?REQUEST=…

  6. Interface Type Metadata Type Hierarchies Interface Instance Metadata Data Type Metadata Data Instance Metadata Combinations of Data/Interface Services & Service Metadata Controlled Vocabularies Catalogs & Registries Interface Type Metadata Type Hierarchies Interface Instance Metadata Data Type Metadata Data Instance Metadata Combinations of Data/Interface End-user End-user Services & Service Metadata Large Data System Large Data System Controlled Vocabularies Catalogs & Registries Coord Trans. Coord Trans. Catalog Catalog Directory Directory WMS WMS WMS WMS i n t e r n e t i n t e r n e t WFS WFS Service Only No Data Service Only No Data FTP FTP Inventory Inventory Catalog Service Catalog Service Access Access Inventory Inventory Single Service Single Service Data Only No Service Data Only No Service Multiple Service Same Data Multiple Service Same Data http://ceos.org 100,50,2 300,75.4 X=56 http://ceos.org 100,50,2 300,75.4 X=56 Technical ChallengesMetadata & Vocabularies Interface Type Metadata Type Hierarchies Interface Instance Metadata Data Type Metadata Data Instance Metadata Combinations of Data/Interface Services & Service Metadata Controlled Vocabularies Catalogs & Registries

  7. HTTP GET/POST based interfaces Service instances provide their own metadata service descriptions (“Capabilities”) via XML Filter parameters allow selection of subsets of source data Output formats advertised by each service instance http://ceos.org 100,50,2 300,75.4 X=56 OGC Services WCS coverage data WMS maps WFS feature data <Roads> <Road> <gml:name>M11</gml:name> <gml:centerLineOf> <gml:LineString srsName="EPSG:4326"> <gml:coordinates> 0,5.0 20.6,10.7 80.5,60.9 </gml:coordinates> </gml:LineString> </gml:centerLineOf> <classification>motorway</classification> <number>11</number> </Road> </Roads>

  8. Registry should be able to handle any kind of service. Should allow searches against more criteria than WMT-1 catalog Each service’s metadata should be composed of common elements where possible Initially described in the IP2000 Basic Service Model Registry <Roads> <Road> <gml:name>M11</gml:name> <gml:centerLineOf> <gml:LineString srsName="EPSG:4326"> <gml:coordinates> 0,5.0 20.6,10.7 80.5,60.9 </gml:coordinates> </gml:LineString> </gml:centerLineOf> <classification>motorway</classification> <number>11</number> </Road> </Roads> OGC Service Registry Concepts Metadata Metadata Metadata WCS coverage data WMS maps WFS feature data <Roads> <Road> <gml:name>M11</gml:name> <gml:centerLineOf> <gml:LineString srsName="EPSG:4326"> <gml:coordinates> 0,5.0 20.6,10.7 80.5,60.9 </gml:coordinates> </gml:LineString> </gml:centerLineOf> <classification>motorway</classification> <number>11</number> </Road> </Roads>

  9. Two competing registry information models: UDDI and ebXML Two competing means of constructing registries: XML database and OGC Stateless Catalog Three competing Metadata content models: R4, R7, and R8 Not enough consensus, fragmented results Registry <Roads> <Road> <gml:name>M11</gml:name> <gml:centerLineOf> <gml:LineString srsName="EPSG:4326"> <gml:coordinates> 0,5.0 20.6,10.7 80.5,60.9 </gml:coordinates> </gml:LineString> </gml:centerLineOf> <classification>motorway</classification> <number>11</number> </Road> </Roads> OWS1 Service Model Issues Metadata Metadata Metadata WCS coverage data WMS maps WFS feature data <Roads> <Road> <gml:name>M11</gml:name> <gml:centerLineOf> <gml:LineString srsName="EPSG:4326"> <gml:coordinates> 0,5.0 20.6,10.7 80.5,60.9 </gml:coordinates> </gml:LineString> </gml:centerLineOf> <classification>motorway</classification> <number>11</number> </Road> </Roads>

  10.   W3C   WS-I    Navigating theWeb Services Industry Standards Organizations W3C World Wide Web Consortium OASIS Organization for the Advancement of Structured Information Standards WS-I Web Services Interoperability Organization IETF Internet Engineering Task Force Global Grid Forum Major Vendors Microsoft .NET (not an acronym…) Sun ONE (Open Network Environment) IBM Websphere (Based on Apache web server) Acronyms SOAP Simple Object Access Protocol UDDI Universal Description, Discovery and Integration ebXML Electronic Business using eXtensible Markup Language WSDL Web Services Description Language OGSA Open Grid Services Architecture The Web Services industry Big players see big money Much jockeying for position & mindshare Many overlapping/competing standards Not many cross-vendor deployments yet Very complex set of issues(for what seems like a simple concept!) OASIS Sun IBM Microsoft

  11. Some key points • Most real, operational web services exist on intranets and extranets. • There is little evidence of web services on the “open” internet. • Web services are not about “the web”. • Web services are producer-oriented tools. Consumers of web services see a carefully controlled entry point. End-users generally see portals.

  12. The Eight Fallacies of Distributed ComputingHow does the GRID measure up? Peter Deutsch • Essentially everyone, when they first build a distributed application, makes the following eight assumptions. All prove to be false in the long run and all cause big trouble and painful learning experiences. • The network is reliable • Latency is zero • Bandwidth is infinite • The network is secure • Topology doesn't change • There is one administrator • Transport cost is zero • The network is homogeneous • http://java.sun.com/people/jag/Fallacies.html

  13. service Wrapping • How hard is it to wrap an OGC service in a GRID wrapper? • How hard is it to build OGC services that are clients of GRID services? • Can an OGC service be moved to where the data is? • Can an OGC service be moved to where the computecycles are available? network

  14. portal GRID Web Think of this model