1. Geospatial interoperability Prof. Wenwen Li School of Geographical Sciences and Urban Planning 5644 Coor Hall wenwen@asu.edu

2. Outline 1. Geospatial interoperability 2. Open Geospatial Consortium (OGC) 3. OGC Web Services (OWS) 4. OGC for Geospatial Interoperability 5. Summary

3. Concepts Geospatial interoperability Geospatial interoperability is the ability for two different software systems to interact with geospatial information.* Geospatial interoperability is dependent on voluntary, consensus-based standards.* Geospatial standards have been established by the OpenGIS Consortium in a series of specification documents.* * National Aeronautics and Space Administration, Geospatial Interoperability Office (2005) Geospatial Interoperability Return on Investment Study Report.

4. Open Geospatial Consortium (OGC) Found: founded in 1994, Incorporated in US, UK, Australia Members: 385 industry, government, research and university members Mission: to lead in the development, promotion and harmonization of open geospatial standards OpenGIS® Specifications: technical documents used by software engineers to build support for interoperability into their products and services.* * National Aeronautics and Space Administration, Geospatial Interoperability Office (2005) Geospatial Interoperability Return on Investment Study Report.

5. Open Geospatial Consortium (OGC) Organization of OGC Planning Committee: Steering, policy, general management and oversight Technical Committee (TC): Develops specifications, discussion papers, other technical communications. Special Interest Groups (SIGs), Working Groups (WGs) that develop specifications, and Revision WGs that revise specs. Consensus process. Interoperability Program: Practical testbed and pilot projects Speeds specification development Helps bring products to the marketplace

6. Open Geospatial Consortium (OGC) Technology Special Interest Groups (SIGs) Architecture Catalog Features Decision Support GML Metadata Image Exploitation WWW Mapping Location Services Information Communities and Semantics

7. Open Geospatial Consortium (OGC) Domain Special Interest Groups (SIGs) Telecommunications and Utilities Earth Observation Defense and Intel Natural Resources and Environment Disaster Management and Public Safety Europe Australia Working Groups (WGs) & Revision WGs (RWGs) Coordinate Transformation WG & RWG Grid Coverages WG Catalog RWG Open Spatial Publishing and Discovery Infrastructure (OSPDI) WG Simple Features for CORBA RWG

8. OGC Web Services (OWS) Services defined by OGC Includes data access, data display and data processing. Service requests are defined by the Hyper Text Transfer Protocol (HTTP) protocol and are encoded by key-value-pairs (KVP) structures or Extensible Markup Language (XML).* * Shekhar, S., & Xiong, H. (Eds.). (2008). Encyclopedia of GIS. Springer Science & Business Media.

9. OGC Web Services (OWS) Types*: Application services: the interaction between computer and people Portrayal services: the visualization of geospatial data (e.g. Web Map Service- WMS, Web Terrain Services) Data services: the access of geospatial data (e.g. Web Feature Service-WFS, Web Coverage Service-WCS, Sensor Observation Service-SOS) Registry (or catalog) services: the classification, registration, description and access of available geospatial information resources (e.g. Catalog Service-Web, CS-W) Processing services: the methods for processing data (e.g. Web Processing Data-WPS) * OGC 00-014r1, Guidelines for Successful OGC Interface Specifications

10. OGC for Geospatial Interoperability “Standards for geospatial interoperability provide a framework for developers to create software that enables users to access and process geographic data from a variety of sources across a generic computing interface within an open information technology environment.”* a framework for developers access and process from a variety of sources across a generic computing interface within an open information technology environment * Shekhar, S., & Xiong, H. (Eds.). (2008). Encyclopedia of GIS. Springer Science & Business Media.

11. OGC for Geospatial Interoperability

12. Key applications Service tiers Service trading (Publish – Find – Bind) Service chaining Service communication Service interfaces Server implementation

13. OGC for Geospatial Interoperability Service tiers Client tier Application Services tier: Processing Services tier: Information Management Services tier: WMS, WFS, WCS

14. OGC for Geospatial Interoperability Web Mapping Server (WMS) Dynamically produces spatially referenced maps of client-specified ground rectangle from one or more client selected geographic datasets, returning predefined pictorial renderings of maps in an image or graphics format* * Shekhar, S., & Xiong, H. (Eds.). (2008). Encyclopedia of GIS. Springer Science & Business Media.

15. OGC for Geospatial Interoperability Web Mapping Server (WMS) interface GetCapabilities: Obtain service-level metadata GetMap: Obtain a map image GetFeatureInfo: Ask for information about particular features shown on a map. Example (OpenLayers): http://openlayers.org/en/v3.1.0/examples/wms-tiled.html

16. OGC for Geospatial Interoperability Web Feature Server (WFS) “Retrieves features and feature collections stored that meet client-specified selection criteria” * Shekhar, S., & Xiong, H. (Eds.). (2008). Encyclopedia of GIS. Springer Science & Business Media.

17. OGC for Geospatial Interoperability Web Feature Server (WFS) interface GetCapabilities DescribeFeatureType GetFeature Transactional WFS: Transaction LockFeature Example (OpenLayers): http://openlayers.org/en/master/examples/vector-wfs.html

18. OGC for Geospatial Interoperability Web Coverage Server (WCS) “Retrieves client-specified subset of client-specified coverage (or image) dataset”* Coverage data, not pictures. Similar to WFS, but for imagery and other coverage. Supports many formats and encodings. * Shekhar, S., & Xiong, H. (Eds.). (2008). Encyclopedia of GIS. Springer Science & Business Media.

19. OGC for Geospatial Interoperability Differences between WMS, WFS and WCS* Web Mapping Service (WMS): A standard protocol for serving georeferenced map images over the internet that are generated from a map server. With a WMS, you are essentially getting an image of geospatial data (i.e. JPG). Web Coverage Service (WCS): A standard protocol for serving coverage data which returns data with its original semantics (instead of just pictures). WCS can be thought of as the raw geospatial raster data behind an image. With a WCS, you can pull the raw raster information for further analysis. Web Feature Service (WFS): A standard protocol for serving geographical features across the web. A WFS can be thought of as the vector geospatial data behind a map. With a WFS, you can pull only the vector file information for further application. * http://www.exelisvis.com/Home/NewsUpdates/TabId/170/ArtMID/735/ArticleID/13556/Web-Mapping-Service- Web-Coverage-Service-or-Web-Feature-Service-%E2%80%93-What%E2%80%99s-the-Difference.aspxhttp://www.exelisvis.com/Home/NewsUpdates/TabId/170/ArtMID/735/ArticleID/13556/Web-Mapping-Service- Web-Coverage-Service-or-Web-Feature-Service-%E2%80%93-What%E2%80%99s-the-Difference.aspx

20. OGC for Geospatial Interoperability Differences between WMS, WFS and WCS*

21. OGC for Geospatial Interoperability Service Trading (Publish – Find – Bind) Trader (Registry): registers service offered by exporter and returns service to importer upon the request. Exporter (Service): registers services to the trader Importer (Client): obtains services from the trader

22. OGC for Geospatial Interoperability Service Chaining Services can be chained transparently (defined and controlled by the client) Services can be chained translucently (predefined but visible to the client) Services can be chained opaquely (predefined and not visible to client)* * OGC 02-006 & ISO 19119.

23. OGC for Geospatial Interoperability Service Communication* The OWS architecture uses the Internet or equivalent as its distributed computing platform (DCP). Communication uses standard World Wide Web (WWW) protocols, e.g. HTTP GET, HTTP POST, and Simple Object Adaptor Protocol (SOAP) Specific operations are addressed by Uniform Resource Locators (URLs). Data transfer formats are identified by multipurpose Internet Mail Extensions (MIME) The data transferred is often encoded using the Extensible Markup Language (XML) * Shekhar, S., & Xiong, H. (Eds.). (2008). Encyclopedia of GIS. Springer Science & Business Media.

24. Summary The OWS architecture uses the Internet or equivalent as its distributed computing platform (DCP). Communication uses standard World Wide Web (WWW) protocols, e.g. HTTP GET, HTTP POST, and Simple Object Adaptor Protocol (SOAP) Specific operations are addressed by Uniform Resource Locators (URLs). Data transfer formats are identified by multipurpose Internet Mail Extensions (MIME) The data transferred is often encoded using the Extensible Markup Language (XML)