Forewords

The Geoportal's API aims at bringing reference datasets to any application, thus allowing overlays between users' datasets and the reference datasets.

Information found in this documentation heavily rely on the knowledge of Information Technology and Geographical Information. Amongst these technologies, one can find :

• the web : technologies involved in the 2D API are based on Internet technology. Information streams are coming from different servers bringing data to the browser ;
• browser's programming languages : API based web pages are dynamic web pages that mainly use the following three technologies :
  • HyperText Markup Language (HTML) : one has to know how to write an HTML page ;
  • Cascading Style Sheet (CSS) : one has to know how to design the look and feel of an HTML page ;
  • ECMA-262 and alike (JavaScript [1] / ActionScript [2]) : these are the core languages of the WEB 2D API and its components (like OpenLayers). One has to know how to write scripts with at least one of these languages.

• international de jure standards from ISO (International Organization for Standardization), de facto standards from OGC (Open Geospatial Consortium) and OSGeo (Open Source Geospatial Fundation) : geographical services use these standards, on has to have some knowledge about how they work :
  • Web Map Service - Cached (WMS-C) : as ISO/OGC did not provide us with a high performances Web Mapping Service, we have chosen this proposal from MetaCarta. This may change when this OGC's RFC becomes a standard ;
  • Web Map Service (WMS) : maps on the network, this service mainly publishes images (but not only). While the browser is a WMS client through the API, a GIS application can also be a WMS client ;
  • Web Feature Service (WFS) : it acts as a database connector and heavily uses the Geographic Markup Language (GML) for transferring geographical data between the service and its clients. Again, the browser is a WFS client through the API, a GIS application can also be a WFS client ;
  • Keyhole Markup Language (KML) : this language is being adopted by OGC. It is well known when used with Google Earth application. OpenLayers supports it ;
  • GPS eXchange Format (GPX) : this language, also supported by the API, is used to interchange GPS tracks, routes or waypoints.

The above technologies are not the only ones to know in the field of geomatics ...

The following diagram shows the overall architecture of the API :

The above diagram shows three main parts :

• server-side components :

  Datastores are located there. They are either managed through database software (postgreSQL, mySQL, Oracle, Informix, ArcSDE, etc ...) or directly filesystem based like folders or caches.

• service-side components :

  They are accessed through services (Web Map Service, Web Feature Service, ...) or by usual HTTP file transfers (Keyhole Markup Language, ...). Another important component also resides on service-side : the Geographical Digital Right Management service (aka, GeoDRM or GeoRM). This service manages the license coming from clients.

• client-side components :

  The API's client is loaded there.

  This component implements the API interfaces with the GeoDRM service.

Geoportal's WMS-C, WMS, WFS services can be plugged to desktop GIS applications. One needs to develop a connector to our GeoRM implementation along with the above services connectors. For more information, please contact us at 'contact dot api at ign dot fr'.

the 2D API

The 2D API allows you to create maps by getting connected to Geoportal's services.