A Roadmap of Open Source components for GI Web Services and Clients

A Paul R CooperMAGIC

Outline

Overview of GI web service architectureStandardsDatabasesWeb serversGIS Server softwareClient softwareClose

Overview of Architecture

Overview of Web services

User interfaces with Client Software.Client Software talks to Server software.Server software contained by Web server.Server Software gets data from Data Store.

Web Server

Client

Datastore

Geoserver

Standards

Why should we be bothered?

Everyone in my field/organization uses <insert data format>International standards allow cross-discipline data sharing.GIS crosses disciplinary boundaries.GIS allows data from different fields/disciplines to be brought togetherDiscipline specific formats do not promote data sharing across disciplines

Standards

All web services depend on standardsGeographic data use OGC standards

(Open Geospatial Consortium)ISO TC211 standards also importantOGC and ISO are convergentBoth depend on W3C standardsXML, CSS, HTML, XHTML, DOM

OGC standards:

Web Feature Servicehttp://www.opengeospatial.org/standards/wfsWeb Map Servicehttp://www.opengeospatial.org/standards/wmsStyled Layer Descriptorhttp://www.opengeospatial.org/standards/sldGML (also ISO 19136)http://www.opengeospatial.org/standards/gmlFilter Encodinghttp://www.opengeospatial.org/standards/filter

ISO Standards

Plenty to choose from!Full list at http://www.isotc211.org/Ones that are of interest to us are:ISO 19110 (Feature Cataloguing).ISO 19111 (Spatial Referencing by Coordinates)ISO 19112 (Spatial Referencing by Geographic identifier)ISO 19115 and ISO 19139 (Metadata)Plus lots more.ISO standards not free, unfortunately.

Web standards

XMLhttp://www.w3.org/XML/HTML and XHTMLhttp://www.w3.org/MarkUp/CSShttp://www.w3.org/Style/CSS/Document Object Model (DOM)http://www.w3.org/DOM/

Other standards

SQL (ISO 9075 with OGC extensions)KML (recently adopted as OGC standard; may converge with GML)

Datastores

Datastores

Any means of storing geographic informationSpatially enabled RDBMS

l PostGIS/PostgreSQL (F/OSS)l MySQL (F/OSS)l Oracle (Proprietary; Oracle Spatial not required)l ArcSDE (Proprietary)

File based l Shapefiles (Proprietary but published and widely used)l Images (Many formats; mostly standard)l GML (OGC standard)

Service based – other WFS servers

Web servers

Web Servers

Apache Stable, and well known web server.

Supports CGI based servicesWeb servers supporting Java

Tomcat Jboss Jetty GlassFish

GIS Web Server

F/OSS Web servers

MapServerGeoserverDeegreeProbably lots of others!

Client Software

Client Software

Many options of varying complexitySimple image, using a suitable URLCustom JavaScriptOpenLayersGoogle EarthGIS Software

Using an IMG tag

Provides a static viewNo interactive facilitiesE.G Ship track in static contextUses a URL specifying:The features to be displayedThe area to be displayedThe bounding boxThe SRID

Javascript based clients

WMS Calls can be scripted in JavaScriptThe ADD used this approach until recently!AdvantagesVery customizableCan be adapted to suit your environmentDisadvantagesNo supportGets complicated quite quickly!Only supports WMS

OpenLayers

An AJAX systemCan use wide variety of data sourcesWMSWFSImagesActively being developedStable and widely used.Documentation not wonderful!

Google Earth

Google Earth can view WMSSome WMS will provide KML output as an option Geoserver does thisKML is an output from a WMSNot a data transfer format

GIS Packages

Most mainstream GIS has at least limited capability to use WMS/WFS.

Summary

Summary

F/OSS software provides good support for GI Web servicesF/OSS software provides good compliance with relevant standardsF/OSS provides stable solutionsF/OSS is easy to use!

That’s All Folks!