QGIS as OGC Data Server¶

WMS capabilities¶

In the WMS capabilities section, you can define the extent advertised in the WMS GetCapabilities response by entering the minimum and maximum X and Y values in the fields under Advertised extent. Clicking Use Current Canvas Extent sets these values to the extent currently displayed in the QGIS map canvas. By checking CRS restrictions, you can restrict in which coordinate reference systems (CRS) QGIS Server will offer to render maps. Use the button below to select those CRSs from the Coordinate Reference System Selector, or click Used to add the CRSs used in the QGIS project to the list.

If you have print composers defined in your project, they will be listed in the GetProjectSettings response, and they can be used by the GetPrint request to create prints, using one of the print composer layouts as a template. This is a QGIS-specific extension to the WMS 1.3.0 specification. If you want to exclude any print composer from being published by the WMS, check Exclude composers and click the button below. Then, select a print composer from the Select print composer dialog in order to add it to the excluded composers list.

If you want to exclude any layer or layer group from being published by the WMS, check Exclude Layers and click the button below. This opens the Select restricted layers and groups dialog, which allows you to choose the layers and groups that you don’t want to be published. Use the Shift or Ctrl key if you want to select multiple entries.

You can receive requested GetFeatureInfo as plain text, XML and GML. Default is XML, text or GML format depends the output format chosen for the GetFeatureInfo request.

If you wish, you can check Add geometry to feature response. This will include in the GetFeatureInfo response the geometries of the features in a text format. If you want QGIS Server to advertise specific request URLs in the WMS GetCapabilities response, enter the corresponding URL in the Advertised URL field. Furthermore, you can restrict the maximum size of the maps returned by the GetMap request by entering the maximum width and height into the respective fields under Maximums for GetMap request.

If one of your layers uses the Map Tip display (i.e. to show text using expressions) this will be listed inside the GetFeatureInfo output. If the layer uses a Value Map for one of its attributes, this information will also be shown in the GetFeatureInfo output.

QGIS supports the following requests for WMS service:

• GetCapabilities
• GetMap
• GetFeatureInfo
• GetLegendGraphic (SLD profile)
• DescribeLayer (SLD profile)
• GetStyles (custom QGIS profile)

WFS capabilities¶

In the WFS capabilities area you can select the layers you want to publish as WFS, and specify if they will allow update, insert and delete operations. If you enter a URL in the Advertised URL field of the WFS capabilities section, QGIS Server will advertise this specific URL in the WFS GetCapabilities response.

QGIS supports the following requests for WFS service:

• GetCapabilities
• DescribeFeatureType
• GetFeature
• Transaction

WCS capabilities¶

In the WCS capabilities area, you can select the layers that you want to publish as WCS. If you enter a URL in the Advertised URL field of the WCS capabilities section, QGIS Server will advertise this specific URL in the WCS GetCapabilities response.

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, WFS and WCS. Add the WMS, WFS and WCS as described in Loading WMS/WMTS Layers, WFS and WFS-T Client and WCS Client to QGIS and load the data. The URL is:

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

QGIS supports the following requests for WCS service:

• GetCapabilities
• DescribeCoverage
• GetCoverage

GetCapabilities Caching¶

In order to improve response time, QGIS Server caches the responses to the GetCapabilities requests. When such a request comes, QGIS Server is caching the response and marking the cache valid. At the same time, it watches if the project file changes. If the project is changed then the cache is marked as invalid and QGIS Server waits for a new request in order to recreate the cache.

Fine tuning your OWS¶

For vector layers, the Fields menu of the Layer ‣ Properties dialog allows you to define for each attribute if it will be published or not. By default, all the attributes are published by your WMS and WFS. If you don’t want a specific attribute to be published, uncheck the corresponding checkbox in the WMS or WFS column.

You can overlay watermarks over the maps produced by your WMS by adding text annotations or SVG annotations to the project file. See the Annotation Tools section for instructions on creating annotations. For annotations to be displayed as watermarks on the WMS output, the Fixed map position checkbox in the Annotation text dialog must be unchecked. This can be accessed by double clicking the annotation while one of the annotation tools is active. For SVG annotations, you will need either to set the project to save absolute paths (in the General menu of the Project ‣ Project Properties dialog) or to manually modify the path to the SVG image so that it represents a valid relative path.

Extra parameters supported by all request types¶

• FILE_NAME parameter: if set, the server response will be sent to the client as a file attachment with the specified file name.

• MAP parameter: Similar to MapServer, the MAP parameter can be used to specify the path to the QGIS project file. You can specify an absolute path or a path relative to the location of the server executable (qgis_mapserv.fcgi). If not specified, QGIS Server searches for .qgs files in the directory where the server executable is located.

  Example:

  http://localhost/cgi-bin/qgis_mapserv.fcgi?\
    REQUEST=GetMap&MAP=/home/qgis/mymap.qgs&...

Extra parameters supported by the WMS GetMap request¶

In the WMS GetMap request, QGIS Server accepts a couple of extra parameters in addition to the standard parameters according to the OGC WMS 1.3.0 specification:

• DPI parameter: The DPI parameter can be used to specify the requested output resolution.

  Example:

  http://localhost/cgi-bin/qgis_mapserv.fcgi?REQUEST=GetMap&DPI=300&...

• IMAGE_QUALITY parameter is only used for JPEG images. By default, the JPEG compression is -1. You can change the default per QGIS project in the OWS Server ‣ WMS capabilities menu of the Project ‣ Project Properties dialog. If you want to override it in a GetMap request you can do it using the IMAGE_QUALITY parameter:

  http://localhost/cgi-bin/qgis_mapserv.fcgi?\
   REQUEST=GetMap&FORMAT=image/jpeg&IMAGE_QUALITY=65&...
  

• image/png; mode= can be used to override the png format. You can choose between image/png; mode=16bit, image/png; mode=8bit and image/png; mode=1bit. This can shrink the output image size quite a bit. Example:

  http://localhost/cgi-bin/qgis_mapserv.fcgi?\
   REQUEST=GetMap&FORMAT=image/png; mode=8bit&...
  

• OPACITIES parameter: Opacity can be set on layer or group level. Allowed values range from 0 (fully transparent) to 255 (fully opaque).

  Example:

  http://localhost/cgi-bin/qgis_mapserv.fcgi?\
    REQUEST=GetMap&LAYERS=mylayer1,mylayer2&OPACITIES=125,200&...

• FILTER parameter: Subsets of layers can be selected with the FILTER parameter. Syntax is basically the same as for the QGIS subset string. However, there are some restrictions to avoid SQL injections into databases via QGIS server:

  Text strings need to be enclosed with quotes (single quotes for strings, double quotes for attributes) A space between each word / special character is mandatory. Allowed Keywords and special characters are ‘AND’,’OR’,’IN’,’=’,’<’,’>=’, ‘>’,’>=’,’!=*,’(‘,’)’. Semicolons in string expressions are not allowed

  Example:

  http://myserver.com/cgi/qgis_mapserv.fcgi?REQUEST=GetMap&LAYERS=mylayer1,mylayer2&FILTER=mylayer1:"OBJECTID" = 3;mylayer2:'text' = 'blabla'&....

• SELECTION parameter: The SELECTION parameter can highlight features from one or more layers. Vector features can be selected by passing comma separated lists with feature ids in GetMap and GetPrint.

  Example:

  http://myserver.com/cgi/qgis_mapserv.fcgi?REQUEST=GetMap&LAYERS=mylayer1,mylayer2&SELECTION=mylayer1:3,6,9;mylayer2:1,5,6&...

  The following image presents the response from a GetMap request using the SELECTION option e.g. http://myserver.com/...&SELECTION=countries:171,65. As those features id’s correspond in the source dataset to France and Romania they’re highlighted in yellow.

  

  Server response to a GetMap request with SELECTION parameter

REDLINING¶

This feature is available and can be used with GetMap and GetPrint requests.

The redlining feature can be used to pass geometries and labels in the request which are overlapped by the server over the standard returned image (map). This permits the user to put emphasis or maybe add some comments (labels) to some areas, locations etc. that are not in the standard map.

The request is in the format:

http://qgisplatform.demo/cgi-bin/qgis_mapserv.fcgi?map=/world.qgs&SERVICE=WMS&VERSION=1.3.0&
REQUEST=GetMap
...
&HIGHLIGHT_GEOM=POLYGON((590000 5647000, 590000 6110620, 2500000 6110620, 2500000 5647000, 590000 5647000))
&HIGHLIGHT_SYMBOL=<StyledLayerDescriptor><UserStyle><Name>Highlight</Name><FeatureTypeStyle><Rule><Name>Symbol</Name><LineSymbolizer><Stroke><SvgParameter name="stroke">%23ea1173</SvgParameter><SvgParameter name="stroke-opacity">1</SvgParameter><SvgParameter name="stroke-width">1.6</SvgParameter></Stroke></LineSymbolizer></Rule></FeatureTypeStyle></UserStyle></StyledLayerDescriptor>
&HIGHLIGHT_LABELSTRING=Write label here
&HIGHLIGHT_LABELSIZE=16
&HIGHLIGHT_LABELCOLOR=%23000000
&HIGHLIGHT_LABELBUFFERCOLOR=%23FFFFFF
&HIGHLIGHT_LABELBUFFERSIZE=1.5

Here is the image outputed by the above request in which a polygon and a label are drawn on top of the normal map:

Server response to a GetMap request with redlining parameters

You can see there are several parameters in this request:

• HIGHLIGHT_GEOM: You can add POINT, MULTILINESTRING, POLYGON etc. It supports multipart geometries. Here is an example: HIGHLIGHT_GEOM=MULTILINESTRING((0 0, 0 1, 1 1)). The coordinates should be in the CRS of the GetMap/GetPrint request.
• HIGHLIGHT_SYMBOL: This controls how the geometry is outlined and you can change the stroke width, color and opacity.
• HIGHLIGHT_LABELSTRING: You can pass your labeling text to this parameter.
• HIGHLIGHT_LABELSIZE: This parameter controls the size of the label.
• HIGHLIGHT_LABELCOLOR: This parameter controls the label color.
• HIGHLIGHT_LABELBUFFERCOLOR: This parameter controls the label buffer color.
• HIGHLIGHT_LABELBUFFERSIZE: This parameter controls the label buffer size.

Extra parameters supported by the WMS GetFeatureInfo request¶

QGIS Server WMS GetFeatureInfo requests supports the following extra optional parameters to define the tolerance for point, line and polygon layers:

• FI_POINT_TOLERANCE parameter: Tolerance for point layers GetFeatureInfo request, in pixels.
• FI_LINE_TOLERANCE parameter: Tolerance for linestring layers GetFeatureInfo request, in pixels.
• FI_POLYGON_TOLERANCE parameter: Tolerance for polygon layers GetFeatureInfo request, in pixels.

GetPrint request¶

QGIS server has the capability to create print composer output in pdf or pixel format. Print composer windows in the published project are used as templates. In the GetPrint request, the client has the possibility to specify parameters of the contained composer maps and labels.

Example:

The published project has two composer maps. In the GetProjectSettings response, they are listed as possible print templates:

<WMS_Capabilities>
...
<ComposerTemplates xsi:type="wms:_ExtendedCapabilities">
<ComposerTemplate width="297" height="210" name="Druckzusammenstellung 1">
<ComposerMap width="171" height="133" name="map0"/>
<ComposerMap width="49" height="46" name="map1"/></ComposerTemplate>
</ComposerTemplates>
...
</WMS_Capabilities>

The client has now the information to request a print output:

http://myserver.com/cgi/qgis_mapserv.fcgi?...&REQUEST=GetPrint&TEMPLATE=Druckzusammenstellung 1&map0:EXTENT=xmin,ymin,xmax,ymax&map0:ROTATION=45&FORMAT=pdf&DPI=300

Parameters in the GetPrint request are:

• <map_id>:EXTENT gives the extent for a composer map as xmin,ymin,xmax,ymax.
• <map_id>:ROTATION map rotation in degrees
• <map_id>:GRID_INTERVAL_X, <map_id>:GRID_INTERVAL_Y Grid line density for a composer map in x- and y-direction
• <map_id>:SCALE Sets a mapscale to a composer map. This is useful to ensure scale based visibility of layers and labels even if client and server may have different algorithms to calculate the scale denominator
• <map_id>:LAYERS, <map_id>:STYLES possibility to give layer and styles list for composer map (useful in case of overview maps which should have only a subset of layers)

GetLegendGraphics request¶

Several additional parameters are available to change the size of the legend elements:

• BOXSPACE space between legend frame and content (mm)
• LAYERSPACE versical space between layers (mm)
• LAYERTITLESPACE vertical space between layer title and items following (mm)
• SYMBOLSPACE vertical space between symbol and item following (mm)
• ICONLABELSPACE horizontal space between symbol and label text (mm)
• SYMBOLWIDTH width of the symbol preview (mm)
• SYMBOLHEIGHT height of the symbol preview (mm)

These parameters change the font properties for layer titles and item labels:

• LAYERFONTFAMILY / ITEMFONTFAMILY font family for layer title / item text
• LAYERFONTBOLD / ITEMFONTBOLD ‘TRUE’ to use a bold font
• LAYERFONTSIZE / ITEMFONTSIZE Font size in point
• LAYERFONTITALIC / ITEMFONTITALIC ‘TRUE’ to use italic font
• LAYERFONTCOLOR / ITEMFONTCOLOR Hex color code (e.g. #FF0000 for red)
• LAYERTITLE / RULELABEL (from QGIS 2.4) set them to ‘FALSE’ to get only the legend graphics without labels

Contest based legend. These parameters let the client request a legend showing only the symbols for the features falling into the requested area:

• BBOX the geographical area for which the legend should be built
• CRS / SRS the coordinate reference system adopted to define the BBOX coordinates
• WIDTH / HEIGHT if set these should match those defined for the GetMap request, to let QGIS Server scale symbols according to the map view image size.

Contest based legend features are based on the UMN MapServer implementation:

GetProjectSettings request¶

This request type works similar to GetCapabilities, but it is more specific to QGIS Server and allows a client to read additional information which is not available in the GetCapabilities output:

• initial visibility of layers
• information about vector attributes and their edit types
• information about layer order and drawing order
• list of layers published in WFS

DXF Export¶

It is possible to export layers in the DXF format using the GetMap Request. Only layers that have read access in the WFS service are exported in the DXF format. Here is a valid REQUEST and a documentation of the available parameters:

http://your.server.address/wms/liegenschaftsentwaesserung/abwasser_werkplan?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&LAYERS=Haltungen,Normschacht,Spezialbauwerke&STYLES=&CRS=EPSG%3A21781&BBOX=696136.28844801,245797.12108743,696318.91114315,245939.25832905&WIDTH=1042&HEIGHT=811&FORMAT=application/dxf&FORMAT_OPTIONS=MODE:SYMBOLLAYERSYMBOLOGY;SCALE:250&FILE_NAME=werkplan_abwasser.dxf

Parameters:

• FORMAT=application/dxf
• FILE_NAME=yoursuggested_file_name_for_download.dxf
• FORMAT_OPTIONS=see options below, key:value pairs separated by Semicolon

FORMAT_OPTIONS Parameters:

• SCALE:scale to be used for symbology rules, filters and styles (not an actual scaling of the data - data remains in the original scale).
• MODE:NOSYMBOLOGY|FEATURESYMBOLOGY|SYMBOLLAYERSYMBOLOGY corresponds to the three export options offered in the QGIS Desktop DXF export dialog.
• LAYERSATTRIBUTES:yourcolumn_with_values_to_be_used_for_dxf_layernames - if not specified, the original QGIS layer names are used.
• USE_TITLE_AS_LAYERNAME if enabled, the title of the layer will be used as layer name.

Extra parameters supported by the WFS GetFeature request¶

In the WFS GetFeature request, QGIS Server accepts two extra parameters in addition to the standard parameters according to the OGC WFS 1.0.0 specification:

• GeometryName parameter: this parameter can be used to get the extent or the centroid as the geometry or no geometry if none if used (ie attribute only). Allowed values are extent, centroid or none.
• StartIndex parameter: STARTINDEX is standard in WFS 2.0, but it’s an extension for WFS 1.0.0 which is the only version implemented in QGIS Server. STARTINDEX can be used to skip some features in the result set and in combination with MAXFEATURES will provide for the ability to use WFS GetFeature to page through results. Note that STARTINDEX=0 means start with the first feature, skipping none.

QGIS Server logging¶

To log requests sent to the server, set the following environment variables:

• QGIS_SERVER_LOG_FILE: Specify path and filename. Make sure that the server has proper permissions for writing to file. File should be created automatically, just send some requests to server. If it’s not there, check permissions.

• QGIS_SERVER_LOG_LEVEL: Specify desired log level. Available values are:

  • 0 INFO (log all requests),
  • 1 WARNING,
  • 2 CRITICAL (log just critical errors, suitable for production purposes).

  Example:

  SetEnv QGIS_SERVER_LOG_FILE /var/tmp/qgislog.txt
  SetEnv QGIS_SERVER_LOG_LEVEL 0
  

Short name for layers, groups and project¶

A number of elements have both a <Name> and a <Title>. The Name is a text string used for machine-to-machine communication while the Title is for the benefit of humans.

For example, a dataset might have the descriptive Title “Maximum Atmospheric Temperature” and be requested using the abbreviated Name “ATMAX”. User can already set title for layers, groups and project.

OWS name is based on the name used in layer tree. This name is more a label for humans than a name for machine-to-machine communication.

QGIS Server supports:

• short name line edits to layers properties You can change this by right clicking on a layer, choose Properties ‣ Metadata tab ‣ Description ‣ Short name.

• WMS data dialog to layer tree group (short name, title, abstract)

  By right clicking on a layer group and selecting the Set Group WMS data option you will get:

  

  Set group WMS data dialog

• short name line edits to project properties - add a regexp validator "^[A-Za-z][A-Za-z0-9\._-]*" to short name line edit accessible through a static method

• add a regexp validator "^[A-Za-z][A-Za-z0-9\._-]*" to short name line edit accessible through a static method

  You can choose a short name for the project root by going to Project properties ‣ OWS Server ‣ Service capabilities ‣ Short name.

• add a TreeName element in the fullProjectSettings

If a short name has been set for layers, groups or project it is used by QGIS Sever as the layer name.

Connection to service file¶

In order to make apache aware of the PostgreSQL service file (see the PostgreSQL Service connection file section) you need to make your *.conf file look like:

SetEnv PGSERVICEFILE /home/web/.pg_service.conf

<Directory "/home/web/apps2/bin/">
  AllowOverride None
.....

Add fonts to your linux server¶

Keep in mind that you may use QGIS projects that point to fonts that may not exist by default on other machines. This means that if you share the project, it may look different on other machines (if the fonts don’t exist on the target machine).

In order to ensure this does not happen you just need to install the missing fonts on the target machine. Doing this on desktop systems is usually trivial (double clicking the fonts).

For linux, if you don’t have a desktop environment installed (or you prefer the command line) you need to:

• On Debian based systems:

  $ sudo su
  $ mkdir -p /usr/local/share/fonts/truetype/myfonts && cd /usr/local/share/fonts/truetype/myfonts
  
  # copy the fonts from their location
  $ cp /fonts_location/* .
  
  $ chown root *
  $ cd .. && fc-cache -f -v
  

• On Fedora based systems:

  $ sudo su
  $ mkdir /usr/share/fonts/myfonts && cd /usr/share/fonts/myfonts
  
  # copy the fonts from their location
  $ cp /fonts_location/* .
  
  $ chown root *
  $ cd .. && fc-cache -f -v
  

Environment variables¶

You can configure some aspects of QGIS server by setting environment variables. For example, to set QGIS server on Apache to use /path/to/config/QGIS/QGIS2.ini settings file, add to Apache config:

SetEnv QGIS_OPTIONS_PATH "/path/to/config/"

or, if using fcgi:

FcgidInitialEnv QGIS_OPTIONS_PATH "/path/to/config/"

This is a list of the variables supported by QGIS server:

• QGIS_OPTIONS_PATH: Specifies the path to the directory with settings. It works the same way as QGIS application –optionspath option. It is looking for settings file in <QGIS_OPTIONS_PATH>/QGIS/QGIS2.ini.
• QUERY_STRING: The query string, normally passed by the web server. This variable can be useful while testing QGIS server binary from the command line.
• QGIS_PROJECT_FILE: the .qgs project file, normally passed as a parameter in the query string, you can also set it as an environment variable (for example by using mod_rewrite Apache module).
• QGIS_SERVER_LOG_FILE: Specify path and filename. Make sure that server has proper permissions for writing to file. File should be created automatically, just send some requests to server. If it’s not there, check permissions.
• QGIS_SERVER_LOG_LEVEL: Specify desired log level. See QGIS Server logging
• MAX_CACHE_LAYERS: Specify the maximum number of cached layers (default: 100).
• DISPLAY: This is used to pass (fake) X server display number (needed on Unix-like systems).
• QGIS_PLUGINPATH: Useful if you are using Python plugins for the server, this sets the folder that is searched for Python plugins.
• DEFAULT_DATUM_TRANSFORM: Define datum transformations between two projections, e.g. EPSG:21781/EPSG:2056/100001/-1;EPSG:2056/EPSG:21781/-1/100001 sets the transformation between CH1903 LV03 (EPSG:21781) and CH1903 LV95 (EPSG:2056) and vice versa. You also need to place grid shift .gsb files in the directory where proj4 stores the grid shift files, e.g. in /usr/share/proj. You need to run crssync after you added new .gsb files and look up the ID in the srs.db. Look at attribute coord_op_code of table tbl_datum_transform in srs.db to find the correct entry.