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QGIS Server

QGIS Server is an open source WMS 1.3 and WFS 1.0.0 implementation which, in addition, implements advanced cartographic features for thematic mapping. The QGIS Server is a FastCGI/CGI (Common Gateway Interface) application written in C++ that works together with a webserver (e.g. Apache, Lighttpd). It is funded by the EU projects Orchestra, Sany and the city of Uster in Switzerland.

It uses QGIS as backend for the GIS logic and for map rendering. Furthermore the Qt library is used for graphics and for platform independent C++ programming. In contrast to other WMS software, the QGIS Server uses cartographic rules as a configuration language, both for the server configuration and for the user-defined cartographic rules.

Moreover, the QGIS Server project provides the ‘Publish to Web’ plugin, a plugin for QGIS desktop which exports the current layers and symbology as a web project for QGIS Server (containing cartographic visualization rules expressed in SLD).

As QGIS desktop and QGIS Server use the same visualization libraries, the maps that are published on the web look the same as in desktop GIS. The ‘Publish to Web’ plugin currently supports basic symbolization, with more complex cartographic visualization rules introduced manually. As the configuration is performed with the SLD standard and its documented extensions, there is only one standardised language to learn, which greatly simplifies the complexity of creating maps for the Web.

In one of the following manuals we will provide a sample configuration to set up a QGIS Server. But for now we recommend to read one of the following URLs to get more information:

Sample installation on Debian Squeeze

At this point we will give a short and simple sample installation howto for Debian Squeeze. Many other OS provide packages for QGIS Server, too. If you have to build it all from source, please refer to the URLs above.

Apart from qgis and qgis-mapserver you need a webserver, in our case apache2. You can install all packages with aptitude or apt-get install together with other necessary dependency packages. After installation you should test, if the webserver and qgis server works as expected. Make sure the apache server is running with /etc/init.d/apache2 start. Open a web browser and type URL: http://localhost. If apache is up, you should see the message ‘It works!’.

Now we test the qgis server installation. The qgis_mapserv.fcgi is available at /usr/lib/cgi-bin/qgis_mapserv.fcgi and provides a standard wms that shows the state boundaries of Alaska. Add the WMS with the URL http://localhost/cgi-bin/qgis_mapserv.fcgi as described in Selecting WMS Servers.

Figure Server 1:

../../../_images/standard_wms_usa.png

Standard WMS with USA boundaries included in the qgis server (KDE) nix

Creating a WMS/WFS from a QGIS project

To provide a new qgis wms/wfs server we have to create a qgis project file with some data. Here we use the ‘alaska’ shapefile from the qgis_sample_dataset. Define the colors and styles of the layers in QGIS and define the project CRS, if not already done.

Figure Server 2:

../../../_images/ows_server_definition.png

Definitions for a qgis project WMS/WFS server (KDE)

Then open the OWS Server tab in the menu Settings ‣ Project Properties and define the general fields under ‘Service Capabilities’. For WMS Capabilities define ‘Coordinate System Restrictions’ and ‘Advertised Extend’. Additionally you can enable the checkbox checkbox Add WKT geometry to feature into response to make the layers queryable and add a ‘Maximum width’ and height that can be requested. For WFS Capabilities you only need to select the layers that you want to provide as WFS. Now save the session in a project file alaska.qgs. To provide the project as a WMS/WFS, we create a new folder /usr/lib/cgi-bin/project with admin privileges and add the project file alaska.qgs and a copy of the qgis_mapserv.fcgi file - that’s all.

Now we test our project WMS and WFS, add the WMS and WFS as described in Loading WMS Layers and WFS and WFS-T Client to QGIS and load the WMS. The URL is:

http://localhost/cgi-bin/project/qgis_mapserv.fcgi