DSTT Report - OGC Services May 8, 2002Page 1 Allan Doyle DSTT Report OGC Services DSTT Report OGC &...

DSTT Report - OGC ServicesMay 8, 2002 Allan Doyle

DSTT ReportOGC ServicesDSTT Report

OGC & GRID Services

Allan DoyleNASA/II

May 8, 2002

CE SCommittee on Earth Observation SatellitesWorking Group on Information Systems and Services


“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


Info

OGC Services

http://www.intl-interfaces.net/servicemodel

GRID Services

http://www.globus.org/ogsa/


1999 2000 2001 2002

OpenGIS® Abstract SpecTopic 12 - The OpenGIS

Service Architecture

Architecture SIG

WWW Mapping SIG

Basic Service ModelDiscussion Paper

Web Registry ServicesDiscussion Paper

CEOS WTF-GOFC

WMT-1 IP2000 (WMT-2) IP2001 (OWS-1) OWS 1.2

OpenGIS® Catalog Interface Implementation Specification 1.0

OpenGIS® Catalog Interface Implementation Specification 1.1

ebXML

Microsoft .NET

UDDI

CEOS WTF (??)

NASA

Industry

OGC

Google

ECHO

Grid Services

Services Time Line

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

ServicemodelAd Hoc

GCMD (SERFs)


A. Search for Services first• Decision support community view ?

B. Search for Data first• Science community view ?

Technical ChallengesData vs. Services

<service name=WMS> <layer name=“FirePoint”>

… <dataURL=ftp://…>

ClientApplication

GetFeature GetMap GetCoverage

ServiceCatalog

WFS

FeatureDataStore

WMS

MapDataStore

WCS

CoverageDataStore

FusionServices

GeocodeGeoParseGeoLink

DataCatalog

<dataset name=MODIS> <Online_Resource name=“WMS”> http://foo.org/wms.cgi?REQUEST=…

Develop metadata and discovery mechanisms that can support both service-centric and data-centric modes.


Interface Type MetadataType HierarchiesInterface Instance MetadataData Type MetadataData Instance MetadataCombinations of Data/InterfaceServices & Service MetadataControlled Vocabularies Catalogs & Registries

End-user

WMS

Single Service

WMS

WFS

Multiple ServiceSame Data

CoordTrans.

Service OnlyNo Data

FTP

Data OnlyNo Service

Catalog

CatalogService

InventoryAccess

http://ceos.org100,50,2300,75.4X=56

Directory

Inventory

LargeData System

i n t e r n e t

Interface Type MetadataType Hierarchies

Interface Instance MetadataData Type MetadataData Instance MetadataCombinations of Data/InterfaceServices & Service MetadataControlled Vocabularies

Catalogs & Registries

Interface Type MetadataType HierarchiesInterface Instance MetadataData Type MetadataData Instance MetadataCombinations of Data/InterfaceServices & Service MetadataControlled Vocabularies Catalogs & Registries

End-user

WMS

Single Service

WMS

WFS

Multiple ServiceSame Data

CoordTrans.

Service OnlyNo Data

FTP

Data OnlyNo Service

Catalog

CatalogService

InventoryAccess

http://ceos.org100,50,2300,75.4X=56

Directory

Inventory

LargeData System

i n t e r n e t

Technical ChallengesMetadata & Vocabularies


OGC Services• 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.org100,50,2300,75.4X=56

WMSmaps

WFSfeature data

WCScoverage 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>


OGC Service Registry Concepts• 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

WMSmaps

WFSfeature data

WCScoverage data


Metadata

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>

Metadata

Metadata


OWS1 Service Model Issues• 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

WMSmaps

WFSfeature data

WCScoverage data


Metadata

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>

Metadata

Metadata


Navigating theWeb Services Industry

The Web Services industryBig players see big moneyMuch jockeying for position & mindshareMany overlapping/competing standardsNot many cross-vendor deployments yetVery complex set of issues

(for what seems like a simple concept!)

OASIS

WS-I

W3C

Standards OrganizationsW3C

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 ForumMajor Vendors

Microsoft .NET (not an acronym…)

Sun ONE (Open Network Environment)

IBM Websphere (Based on Apache web server)

AcronymsSOAP

Simple Object Access Protocol

UDDI Universal Description, Discovery and Integration

ebXML Electronic Business using eXtensible Markup Language

WSDL Web Services Description Language

OGSAOpen Grid Services Architecture

Micro

soft

Sun

IBM


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.


The Eight Fallacies of Distributed Computing

How 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.

2. Latency is zero3. Bandwidth is infinite4. The network is secure5. Topology doesn't change6. There is one administrator7. Transport cost is zero8. The network is homogeneous

– http://java.sun.com/people/jag/Fallacies.html

1. The network is reliable


• 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 compute

cycles are available?

Wrapping

network

service


Think of this model

portal

GRID Web

DSTT Report - OGC Services May 8, 2002Page 1 Allan Doyle DSTT Report OGC Services DSTT Report OGC &...

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