1	Interoperability in Geospatial Web Services Jeff de La Beaujardière, PhD NASA Geospatial Interoperability Office Editor, WMS 1.1 Specification jeff2002@sunrise.gsfc.nasa.gov +1 301-286-1569
2	The Problem Most existing internet map & data servers are not "interoperable" each has vendor-specific access method access often requires human operator service metadata is not standardized
3	The Solution Standardized protocols for requesting geospatial information & services via HTTP Well-defined schema for service metadata
4	Open GIS Consortium (OGC) GIS = Geographic Information System OGC Members: 220+ institutions worldwide software vendors, government, universities Consensus development of open standards for interoperability Current focus on geospatial web services Building on HTTP, XML, etc Experimenting with WSDL, SOAP, UDDI
5	OGC Testbeds Sponsorship by government agencies (or corporations) Cost sharing funds to vendors & academia Collaborative development of specifications Iterative prototyping Proven interoperability through working software
6	Web Map Service WMS 1.0: 2000-04, WMS 1.1.1: 2002-04 Scope: geographic data rendered as an image (a "map"), not actual data values Operations: GetCapabilities - send service metadata GetMap - produce map of desired area GetFeatureInfo (opt.) - describe feature at point
7	Standardized Service Metadata Each OGC Web Service (OWS) is self-describing GetCapabilities operation - predefined URL syntax to request service description Response is "Capabilities XML" document (XML = Extensible Markup Language) Standard format & vocabulary automatically parsed by Clients harvested by Catalogs legible to humans if necessary
8	WMS Metadata Title of server and general information Base URL for each operation List of map layers available For each map layer, possible metadata include: Name, Title, Abstract, Keywords Coordinate systems & bounding boxes Available rendering styles Dimensional parameters (e.g., time) URL of dataset metadata (FGDC/ISO 19115)
9	Standardized Request Messages HTTP GET: parameters appended to base URL SERVICE=WMS&REQUEST=GetCapabilities SERVICE=WMS&REQUEST=GetMap& LAYERS=layers& STYLES=styles& FORMAT=format& SRS=coordinate_system& BBOX=bounding_box& WIDTH=width& HEIGHT=height Map "Client" can simply be a web page! HTTP POST: Request is encoded as XML document
10	Interoperable Web Mapping
11	Broader Adoption of WMS ISO 19128 Committee Draft issued 2002-09 Vote for adoption as Draft Intl Std 2002-12 Commercial vendor products Growing number of servers world-wide Core standard of GeoConnections Canada Core standard of US Geospatial One-Stop
12	viewer.digitalearth.gov
13	WMS Context XML Draft v0.1.4 released 2002-08 Scope: Description of a composite map (from multiple WMS servers) save state of Client application reproduce view in another Client XML document enumerating: map(s) provided by each WMS overall bounding box other useful info
14	Web Feature Service (WFS) WFS 1.0: 2002-09 Scope: storage & retrieval of geographic vector feature data (point/line/polygon) XML data encoding format: Geography Markup Language (GML) Filter Specification: Restrict WFS output based on user criteria Operations: GetCapabilities DescribeFeatureType GetFeature
15	Web Coverage Service (WCS) Draft v0.7 released 2002-04 Scope: Retrieval of gridded, swath, TIN or other "coverage" data in binary or other formats (HDF, GeoTIFF, NITF, NetCDF, etc.) Operations: GetCapabilities GetCoverage
16	Portrayal Services Client submits GetMap request to portrayal service "Enhanced" request includes: URL of 3rd-party WFS or WCS from which to get data URL of Styled Layer Descriptor (SLD) document describing how data are to be represented Response is map image for display by simple client (e.g., web browser)
17	Web Terrain Service Draft v0.3.2 released 2001-08 Scope: Perspective views of terrain, possibly with additional data overlaid A generalization of Web Map Service to views that are not "straight down" Operations: GetCapabilities GetView
18	Gazetteer Draft v0.9 issued 2002-09 A specialization of WFS Scope: Given a place name (or other identifier), return geometry and attributes as a GML Feature User can navigate by place name rather than by coordinates
19	Web Registry Service Draft v0.0.2 issued 2001-01 "Stateless" HTTP version of session-oriented Catalog Service v1.0 (1999) Scope: Searchable catalog of services and data
20	Other Planets! Nothing fundamentally "geo" about these geospatial services except variable coordinate reference system ID
21	Geospatial One-Stop Portal
22	Geospatial One-Stop Portal
23	Summary