June 9-11, 2004 Carleton University Ottawa Canada OGC in Open Source Products Tom Kralidis Jeff McKenna Peter Pulsifer Bart van den Eijnden June 9-11, 2004 Carleton University Ottawa Canada

Interoperability Overview Benefits of OGC in the Organization Examples / Demos OGC / Open Source Issues Comments/Questions/Discussion

June 9-11, 2004 Carleton University Ottawa Canada Interoperability Overview Benefits of OGC in the Organization Examples / Demos OGC / Open Source Issues Comments/Questions/Discussion

Infrastructure Many pieces working independent of make, model Open interface –Can communicate with other things Transparent / Invisible Cooperative Distributed

The Distributed Approach Distributed Spatial Data infrastructure Cost / Feasibility One Source Up-to-date Data Data Management Issues Less: –Local storage space –redundant data How? –Web Services

Web Services Independent of –operating systems –programming languages –Organizations How? –non-proprietary data / messaging standards eXtensible Markup Language (XML)

Web Services Until recently everyone is developing in their own little world (metadata => data => applications) From functionality to interoperability Internet is driving these changes: no net, then little reason to interoperate Being “open” is a strong selling point –E.g. VCR cassettes: VHS vs. BETA –E.g. mix and match your home stereo system components

Web Services- Benefits Lower software integration costs Maintaining legacy systems Using standards lowers IT costs of collaboration with external partners, vendors, clients

Web Services Architecture Approach Applications e.g., Transportation Planning, Climate Change Monitoring, Site Assessment Services e.g., Metadata Service, gazetteer service, Web Map Service Data e.g., topographic, thematic, imagery, toponymy, metadata Users Other Applications For Example… A trip planning web site that calculates the best route between two cities uses Gazetteer service, Road network server, Web mapping service based on Geographical Names, Road network features Base maps

OpenGIS Consortium Standards body for geospatial processing over the Internet –Free, public specification –Rapid specification development using Technology integration experimentation Develop and spec in parallel Testbeds –Sponsor requirements –Industry participation

OGC Specifications WMS WFS WCS Web Map Context GML SLD Filter Catalog WCTS Grid Coverages Location Services Simple Features –CORBA –SQL –OLE/COM

Web Map Service (WMS) Provides images of map data defined by a geographic / spatial component Provides point based query functionality Interoperable means of map compositing

Web Map Service (WMS) Interoperable, ‘just-in-time’ approach to map delivery Map compositing from multi-servers

GeoGratis – Web Mapping: Phase I Toporama:

Web Mapping: Phase I Interoperability Common Standards Services Interoperability Common Standards Services

Web Browser Viewer Client Map Server internet Web Map Servers Web Mapping with WMS

Web Map Service (WMS) Provides images of map data defined by a geographic / spatial component Provides point based query functionality OGC adopted specification –1999: Version –2001: Version –2002: Version CGDI endorsed specification

Web Map Service (WMS) HTTP-based communication –HTTP GET or POST mechanism Operations GetCapabilities GetMap GetFeatureInfo (optional) –Operation keywords are case-insensitive –Operation values are case-sensitive

Web Feature Service (WFS) Feature level access to spatial data –Finer grained access and query Spatial and non-spatial query capability –Attribute and / or geometry Returns GML –Can further transform with XSLT to SVG, style with SLD, etc. Transactional capability –INSERT, UPDATE, DELETE, LOCK, … Security considerations

Web Feature Service (WFS) GetCapabilities –Provides XML ‘Capabilities’ or service functionality metadata, and feature metadata –Parameters Version (version of specification) Service (multiple services may exist from this service, e.g. WMS, WFS, WCS) Request (GetCapabilities) v.cgi?datastore=CEOWARE2&version=1.0.0&service=WF S&request=GetCapabilities

Web Feature Service (WFS) DescribeFeatureType –Provides schema information about a feature type (fieldnames, data types) –Parameters Version (version of specification) Service (multiple services may exist from this service, e.g. WMS, WFS, WCS) Request (DescribeFeatureType) Typename (name of feature type) v.cgi?datastore=CEOWARE2&version=1.0.0&service=WF S&request=DescribeFeatureType&typename=EOS_DAT A_GATEWAYS

Web Feature Service (WFS) GetFeature –Provides query interface of data –Parameters Version (version of specification) Service (multiple services may exist from this service, e.g. WMS, WFS, WCS) Request (GetFeature) Typename (name of feature type) Filter (more on this later) v.cgi?datastore=CEOWARE2&version=1.0.0&service=WF S&request=GetFeature&typename=EOS_DATA_GATEW AYS

Geography Markup Language (GML) XML encoding of geospatial information –XML dialect Basic application framework for handling geospatial information Enables complex features & feature associations between data Human-readable Can be processed by many XML tools in various development environments

Geography Markup Language (GML) GML Schemas Geometry Definitions Application Schema Information Community Definition Instance Document Data Instance As static data or through Service Instance

Geography Markup Language (GML)

New features in version –Topology –Temporal –Enhanced Geometry –Coverages –Units of Measure

Styled Layer Descriptors (SLD) Symbolization to map data Styling Addresses lack of symbolization within current and past OGC services Cartographic design of GeoData Augments OpenGIS specifications –Can custom style WMS content –Can custom style WFS content

Styled Layer Descriptors (SLD)

Example of an SLD document: dev.geoconnections.org/prototypes/sld/gc db.xml

Filter Encoding XML Definition of data query language for online services –GML used for geometry querying semantics –Used as filter grammar for OpenGIS WFS –Stand alone specification Can be applied to any service as a query approach

Filter Encoding Example: ORGID> CCRS Used in OGC WFS – re=CEOWARE2&version=1.0.0&service=WFS&request=GetFeature&ty pename=EOS_DATA_GATEWAYS&filter= ORGID> CCRS

OpenGIS Web Map Context Documents - Overview ‘bookmarkable’ XML encoding of state of a web mapping application Analogous to ‘project’ files in most popular GIS software packages Enables sharing of application scenarios, demonstrative presentations, etc.

Web Mapping – Same data; multiple applications (OpenGIS Web Map Context Documents)

June 9-11, 2004 Carleton University Ottawa Canada Semantic Interoperability Ability to share meaning rather than simply exchange data Semantic heterogeneity: –Same ‘symbol’/term different meaning –Different terms similar meaning OGC currently proposes consensus approach to dealing with semantic heterogeneity Moving towards the use of formal Ontologies

June 9-11, 2004 Carleton University Ottawa Canada Tools –Glossaries and data dictionaries –Thesauri and Taxonomies –Metadata, XML Schemas & Data Models (i.e. ISO 19115, GML, UML) –Formal ontologies and inference: Description logics (DAML+OIL) <-open standard

June 9-11, 2004 Carleton University Ottawa Canada Interoperability Overview Benefits of OGC in the Organization Examples / Demos OGC / Open Source Issues Comments/Questions/Discussion

June 9-11, 2004 Carleton University Ottawa Canada No reinventing the wheel Plug-and-Play with other standards-based systems Multi Vendor Interoperability Underlying system could change – interface remains standards-based –Less impact on end clients –Not tied to specific solutions

June 9-11, 2004 Carleton University Ottawa Canada Interoperability Overview Benefits of OGC in the Organization Examples / Demos OGC / Open Source Issues Comments/Questions/Discussion

June 9-11, 2004 Carleton University Ottawa Canada ProductURLOGC Specification(s) UMN MapServerhttp://mapserver.gis.umn.edu/WMS,WFS,Context,SLD Filter,GML PostGIShttp://postgis.refractions.net/Simple Features for SQL MapBuilderhttp://mapbuilder.sourceforge.net/WMS,Context deegreehttp://deegree.sourceforge.net/WMS,WFS,WCS,WCAS WFS-G,WTS,WCTS GeoServerhttp://geoserver.sourceforge.net/WFS-T maplabhttp:// Chameleonhttp:// inlineWMShttp://sourceforge.net/projects/inlinewmsWMS JUMPhttp:// GEOShttp://geos.refractions.net/Simple Features for SQL gml4jhttp://gml4j.sourceforge.net/GML MySQL Spatialhttp:// Geometry Model MapSurferhttp://mapsurfer.sourceforge.net/WMS PyOGCLibhttp://pyogclib.sourceforge.net/WMS QuickWMShttp:// Studiohttp:// OpenMaphttp://openmap.bbn.com/ GeoToolshttp:// Coverages,WCTS,Filter

June 9-11, 2004 Carleton University Ottawa Canada Demo 1: application framework based on OGC standards and Open Source. Open Source GIS products used: UMN Mapserver Chameleon and PHP/Mapscript OGR (as a PHP module) Deegree WCaS (Web Catalog Server)

June 9-11, 2004 Carleton University Ottawa Canada Application function: find services Uses: OGC Web Services Stateless Catalog Profile (WCAS) ISO19119 datamodel

June 9-11, 2004 Carleton University Ottawa Canada Application function: find layers Uses: OGC Web Services Stateless Catalog Profile (WCAS) ISO19115 datamodel Layers are coupled to services in the ISO19119 datamodel, so an extra request is necessary to find the service on which the layer is available

June 9-11, 2004 Carleton University Ottawa Canada Application function: querybuilder Flow: Perform DescribeLayer request on SLD WMS Perform DescribeFeatureType on associated WFS to get list of columns Use SLD + Filter to highlight features on map

June 9-11, 2004 Carleton University Ottawa Canada Application function: download shapefile Flow: Perform DescribeLayer request on SLD WMS Perform GetFeature with BBOX Filter on associated WFS using AOI defined in application Use OGR to convert GML to shapefile

June 9-11, 2004 Carleton University Ottawa Canada Demo 2 (Jeff McKenna)

June 9-11, 2004 Carleton University Ottawa Canada Interoperability Overview Benefits of OGC in the Organization Examples / Demos OGC / Open Source Issues Comments/Questions/Discussion

June 9-11, 2004 Carleton University Ottawa Canada OGC / Open Source Issues General –“OGC Compliant” – be careful! –Namespaces in OGC XML-based documents

June 9-11, 2004 Carleton University Ottawa Canada OGC / Open Source Issues General –XML (GML) is very expressive yet very verbose -> performance problems –Researchers working on ‘feature streaming’ to deal with this issue (not yet in OGC process) –Applicability of specs in functional applications: bridging the gap –slow emergence of specs

June 9-11, 2004 Carleton University Ottawa Canada OGC / Open Source Issues Semantic –Current consensus approach may limit use outside of simple domains (i.e. where concensus cannot be achieved) –OGC is not the only standard -> ISO, FGDC, Domain specific, W3C -> requires a ‘reference ontology’ to mediate between standards

June 9-11, 2004 Carleton University Ottawa Canada Comments/Questions/Discussion Thanks! Tom Kralidis (tom.kralidis at ec.gc.ca) Jeff McKenna (mckenna at dmsolutions.ca) Peter Pulsifer (pulsifer at magma.ca) Bart van den Eijnden (bart at geodan.nl) June 9-11, 2004 Carleton University Ottawa Canada