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
Why should we be bothered? Everyone in my field/organization uses International standards allow cross-discipline data sharing. GIS crosses disciplinary boundaries. GIS allows data from different fields/disciplines to be brought together Discipline specific formats do not promote data sharing across disciplines
Standards All web services depend on standards Geographic data use OGC standards (Open Geospatial Consortium) ISO TC211 standards also important OGC and ISO are convergent Both depend on W3C standards XML, CSS, HTML, XHTML, DOM
OGC standards: Web Feature Service http://www.opengeospatial.org/standards/wfs Web Map Service http://www.opengeospatial.org/standards/wms Styled Layer Descriptor http://www.opengeospatial.org/standards/sld GML (also ISO 19136) http://www.opengeospatial.org/standards/gml Filter Encoding http://www.opengeospatial.org/standards/filter
ISO Standards Plenty to choose from! Full list at http://www.isotc211.org/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 XML http://www.w3.org/XML/ HTML and XHTML http://www.w3.org/MarkUp/ CSS http://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)
Any means of storing geographic information Spatially enabled RDBMS PostGIS/PostgreSQL (F/OSS) MySQL (F/OSS) Oracle (Proprietary; Oracle Spatial not required) ArcSDE (Proprietary) File based Shapefiles (Proprietary but published and widely used) Images (Many formats; mostly standard) GML (OGC standard) Service based – other WFS servers
Using an IMG tag Provides a static view No interactive facilities E.G Ship track in static context Uses a URL specifying: The features to be displayed The area to be displayed The bounding box The SRID
OpenLayers An AJAX system Can use wide variety of data sources WMS WFS Images Actively being developed Stable and widely used. Documentation not wonderful!
Google Earth Google Earth can view WMS Some WMS will provide KML output as an option Geoserver does this KML is an output from a WMS Not a data transfer format
GIS Packages Most mainstream GIS has at least limited capability to use WMS/WFS.