INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION Introduction to the OGC Web Processing Service (WPS) GIP – Meeting 20 April 2006 Theodor Foerster

Introduction to the OGC Web Processing Service (WPS) 2 Contents  Motivation  WPS in detail  Pitfalls  Conclusion

Introduction to the OGC Web Processing Service (WPS) 3 Situation  Spatial data is available on the web  Through OGC web services (WFS, WCS)  Network & computational capacity available  But users want to have information

Introduction to the OGC Web Processing Service (WPS) 4 Motivation  Execute spatial processes as web services  Platform independent  Availability (worldwide & 24/7)  Maintenance  Reusability  Processing on the web is the next logical step

Introduction to the OGC Web Processing Service (WPS) 5 OGC WPS - history  Founded by the CGDI (2004)  Refined within an OGC interoperability experiment  Discussion paper published in end 2005 under r4  Awaiting adaptation for version 0.

Introduction to the OGC Web Processing Service (WPS) 6 Notion of the WPS  Service communication based on HTTP and XML  No limitations on certain types of processes  No limitations on the data  Supports raster and vector data  Literal values (e.g. buffer size)

Introduction to the OGC Web Processing Service (WPS) 7 WPS operations  GetCapabilities  Service description  Access description  Brief process descriptions  DescribeProcess  Full process description  Execute  Process execution

Introduction to the OGC Web Processing Service (WPS) 8 … … Buffer ProcessingService? REQUEST=DescribeProcess& Identifier=Buffer& SERVICE=WPS& VERSION=0.4.0 Buffer … … BufferResult $XML_Geometries <ProcessDescription Buffer … geometry 1 width … … BufferResult … ProcessingService? REQUEST=GetCapabilities& SERVICE=WPS Buffer geometry $XML_Geometries width 100 WPS in action - Buffering ClientWPS Network request response request response request response Inspired by P. Schut’s presentation at the OGC TC Meeting in Huntsville 2006: “WPS RFC responses”

Introduction to the OGC Web Processing Service (WPS) 9 Additional Features Supports long-term processes by storing  Handles drawback of HTTP  Avoids recalculation  Status of processes is callable  Supports chaining (limited)  For data retrieval & processing  Standardized error messages

Introduction to the OGC Web Processing Service (WPS) 10 Discovered pitfalls  No advanced chaining available  Semantic descriptions of processes are missing  No sophisticated communication pattern incorporated  No key advantage over SOAP

Introduction to the OGC Web Processing Service (WPS) 11 Implementation features - DEMO  WPS identified as a basic module for generalization processing in the web  Written in Java  Published in 52n incubator  Includes server and client (based on JUMP) implementation  Based on open source APIs only  Provides a pluggable mechanism

Introduction to the OGC Web Processing Service (WPS) 12 Conclusion  WPS just evolving  Many open issues  Web Coverage Processing Service introduces additional ideas  Will be part of ITC’s 52n Working group on Geo Processing Service

Introduction to the OGC Web Processing Service (WPS) 13 Thanks Further information under: > Processing Thanks for your attention!