3.2. Web Map Service (WMS)

The 1.1.1 and 1.3.0 WMS standards implemented in QGIS Server provide a HTTP interface to request map or legend images generated from a QGIS project. A typical WMS request defines the QGIS project to use, the layers to render as well as the image format to generate. Basic support is also available for Styled Layer Descriptor (SLD).

Specifications:

Standard requests provided by QGIS Server:

Request	Description
GetCapabilities	Returns XML metadata with information about the server
GetMap	Returns a map
GetFeatureInfo	Retrieves data (geometry and values) for a pixel location
GetLegendGraphic	Returns legend symbols
GetStyle(s)	Returns XML document with style description in SLD
DescribeLayer	Returns information about WFS and WCS availability respectively for vector and raster layers

Vendor requests provided by QGIS Server:

Request	Description
GetPrint	Returns a QGIS layout
GetProjectSettings	Returns specific information about QGIS Server
GetSchemaExtension	Returns XML metadata about optional extended capabilities

3.2.1. GetCapabilities

Standard parameters for the GetCapabilities request according to the OGC WMS 1.1.1 and 1.3.0 specifications:

Parameter	Required	Description
SERVICE	Yes	Name of the service (WMS)
REQUEST	Yes	Name of the request (GetCapabilities)
VERSION	No	Version of the service

The GetCapabilities request supports as well the following vendor parameters:

Parameter	Required	Description
MAP	Yes	QGIS project file

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&VERSION=1.3.0
&REQUEST=GetCapabilities

3.2.2. GetMap

Standard parameters for the GetMap request according to the OGC WMS 1.1.1 and 1.3.0 specifications:

Parameter	Required	Description
SERVICE	Yes	Name of the service (WMS)
REQUEST	Yes	Name of the request (GetMap)
VERSION	Yes	Version of the service
LAYERS	No	Layers to display
STYLES	No	Layers’ style
SRS / CRS	Yes	Coordinate reference system
BBOX	Yes	Map extent
WIDTH	Yes	Width of the image in pixels
HEIGHT	Yes	Height of the image in pixels
FORMAT	No	Image format
TRANSPARENT	No	Transparent background
SLD	No	URL of an SLD to be used for styling
SLD_BODY	No	In-line SLD (XML) to be used for styling

In addition to the standard ones, QGIS Server supports redlining, external WMS layers as well as the following extra parameters:

Parameter	Required	Description
MAP	Yes	QGIS project file
BGCOLOR	No	Specify the background color
DPI	No	Specify the output resolution
IMAGE_QUALITY	No	JPEG compression
OPACITIES	No	Opacity for layer or group
FILTER	No	Subset of features
SELECTION	No	Highlight features
FILE_NAME	No	File name of the downloaded file Only for `FORMAT=application/dxf`
FORMAT_OPTIONS	No	Options of the specified file format Only for `FORMAT=application/dxf`
TILED	No	Working in tiled mode

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&VERSION=1.3.0
&REQUEST=GetMap
&MAP=/home/qgis/projects/world.qgs
&LAYERS=mylayer1,mylayer2,mylayer3
&STYLES=style1,default,style3
&OPACITIES=125,200,125
&CRS=EPSG:4326
&WIDTH=400
&HEIGHT=400
&FORMAT=image/png
&TRANSPARENT=TRUE
&DPI=300
&TILED=TRUE

VERSION

This parameter allows to specify the version of the service to use. Available values for the VERSION parameter are:

1.1.1
1.3.0

According to the version number, slight differences have to be expected as explained later for the next parameters:

CRS / SRS
BBOX

LAYERS

This parameter allows to specify the layers to display on the map. Names have to be separated by a comma.

In addition, QGIS Server introduced some options to select layers by:

the layer id: the project option allowing to select layers by their id is in QGIS Server ► WMS tab of the Project ► Properties… dialog. Check the Use layer ids as names checkbox to activate this option.
a short name

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&LAYERS=mylayerid1,mylayerid2
&...

STYLES

This parameter can be used to specify a layer’s style for the rendering step. Styles have to be separated by a comma. The name of the default style is default.

SRS / CRS

This parameter allows to indicate the map output Spatial Reference System in WMS 1.1.1 and has to be formed like EPSG:XXXX. Note that CRS is also supported if current version is 1.1.1.

For WMS 1.3.0, CRS parameter is preferable but SRS is also supported.

Note that if both CRS and SRS parameters are indicated in the request, then it’s the current version indicated in VERSION parameter which is decisive.

In the next case, the SRS parameter is kept whatever the VERSION parameter because CRS is not indicated:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.3.0
&SRS=EPSG:2854
&...

In the next case, the SRS parameter is kept instead of CRS because of the VERSION parameter:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.1.1
&CRS=EPSG:4326
&SRS=EPSG:2854
&...

In the next case, the CRS parameter is kept instead of SRS because of the VERSION parameter:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.3.0
&CRS=EPSG:4326
&SRS=EPSG:2854
&...

BBOX

This parameter allows to specify the map extent with units according to the current CRS. Coordinates have to be separated by a comma.

The BBOX parameter is formed like min_a,min_b,max_a,max_b but a and b axis definition is different according to the current VERSION parameter:

in WMS 1.1.1, the axis ordering is always east/north
in WMS 1.3.0, the axis ordering depends on the CRS authority

For example in case of EPSG:4326 and WMS 1.1.1, a is the longitude (east) and b the latitude (north), leading to a request like:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.1.1
&SRS=epsg:4326
&BBOX=-180,-90,180,90
&...

But in case of WMS 1.3.0, the axis ordering defined in the EPSG database is north/east so a is the latitude and b the longitude:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.3.0
&CRS=epsg:4326
&BBOX=-90,-180,90,180
&...

WIDTH

This parameter allows to specify the width in pixels of the output image.

HEIGHT

This parameter allows to specify the height in pixels of the output image.

FORMAT

This parameter may be used to specify the format of map image. Available values are:

jpg
jpeg
image/jpeg
image/png
image/png; mode=1bit
image/png; mode=8bit
image/png; mode=16bit
image/webp
application/dxf: only layers that have read access in the WFS service are exported in the DXF format

application/pdf

URL example:

http://localhost/qgisserver?
SERVICE=WMS&VERSION=1.3.0
&REQUEST=GetMap
&FORMAT=application/dxf
&LAYERS=Haltungen,Normschacht,Spezialbauwerke
&CRS=EPSG%3A21781
&BBOX=696136.28844801,245797.12108743,696318.91114315,245939.25832905
&WIDTH=1042
&HEIGHT=811
&FORMAT_OPTIONS=MODE:SYMBOLLAYERSYMBOLOGY;SCALE:250
&FILE_NAME=plan.dxf

TRANSPARENT

This boolean parameter can be used to specify the background transparency. Available values are (not case sensitive):

TRUE
FALSE

However, this parameter is ignored if the format of the image indicated with FORMAT is different from PNG.

BGCOLOR

This parameter allows to indicate a background color for the map image. However it cannot be combined with TRANSPARENT parameter in case of PNG images (transparency takes priority). The colour may be literal or in hexadecimal notation.

URL example with the literal notation:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.3.0
&BGCOLOR=green
&...

URL example with the hexadecimal notation:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.3.0
&BGCOLOR=0x00FF00
&...

DPI

This parameter can be used to specify the requested output resolution.

IMAGE_QUALITY

This 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 ► Properties… dialog. If you want to override it in a GetMap request you can do it using the IMAGE_QUALITY parameter.

OPACITIES

Comma separated list of opacity values. Opacity can be set on layer or group level. Allowed values range from 0 (fully transparent) to 255 (fully opaque).

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.3.0
&WIDTH=400
&HEIGHT=200
&CRS=EPSG:4326
&LAYERS=countries,places
&BBOX=42,-6,52,15
&OPACITIES=255,0

../../../_images/wms_getmap_opacities.png — Fig. 3.2 To the left `OPACITIES=255,0` and to the right `OPACITIES=255,255`

FILTER

A subset of layers can be selected with the FILTER parameter. The 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. If a dangerous string is found in the parameter, QGIS Server will return the next error:

<ServiceExceptionReport>
  <ServiceException code="Security">The filter string XXXXXXXXX has been rejected because of security reasons.
  Note: Text strings have to be enclosed in single or double quotes. A space between each word / special character is mandatory.
  Allowed Keywords and special characters are IS,NOT,NULL,AND,OR,IN,=,<,=<,>,>=,!=,',',(,),DMETAPHONE,SOUNDEX.
  Not allowed are semicolons in the filter expression.</ServiceException>
</ServiceExceptionReport>

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.3.0
&WIDTH=400
&HEIGHT=300
&CRS=EPSG:4326
&BBOX=41,-6,52,10
&LAYERS=countries_shapeburst,countries,places
&FILTER=countries_shapeburst,countries:"name" = 'France';places: "name" = 'Paris'

../../../_images/wms_getmap_filter.png — Fig. 3.3 Server response to a GetMap request with FILTER parameter

In this example, the same filter "name" = 'France' is applied to layers countries and countries_shapeburst, while the filter "name" = 'Paris' is only applied to places.

Note

It is possible to make attribute searches via GetFeatureInfo and omit the X/Y parameter if a FILTER is there. QGIS Server then returns info about the matching features and generates a combined bounding box in the XML output.

SELECTION

The SELECTION parameter can highlight features from one or more layers. Vector features can be selected by passing comma separated lists with feature ids.

http://localhost/qgisserver?
SERVICE=WMS
&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.

../../../_images/server_selection_parameter.png — Fig. 3.4 Server response to a GetMap request with SELECTION parameter

FORMAT_OPTIONS

This parameter can be used to specify options for the selected format. Only for FORMAT=application/dxf in GetMap request. Takes a list of key:value pairs separated by semicolon:

SCALE: to be used for symbology rules, filters and styles (not actual scaling of the data - data remains in the original scale).
MODE: corresponds to the export options offered in the QGIS Desktop DXF export dialog. Possible values are NOSYMBOLOGY, FEATURESYMBOLOGY and SYMBOLLAYERSYMBOLOGY.
LAYERATTRIBUTES: specify a field or in case of many layers a comma separated list of fields that contains values for DXF layer names - 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.
CODEC: specify a codec to be used for encoding. Default is ISO-8859-1 check the QGIS desktop DXF export dialog for valid values.
NO_MTEXT: Use TEXT instead of MTEXT for labels.
FORCE_2D: Force 2D output. This is required for polyline width.

TILED

For performance reasons, QGIS Server can be used in tiled mode. In this mode, the client requests several small fixed size tiles, and assembles them to form the whole map. Doing this, symbols at or near the boundary between two tiles may appeared cut, because they are only present in one of the tile.

Set the TILED parameter to TRUE to tell QGIS Server to work in tiled mode, and to apply the Tile buffer configured in the QGIS project (see Configure your project).

When TILED is TRUE and when a non-zero Tile buffer is configured in the QGIS project, features outside the tile extent are drawn to avoid cut symbols at tile boundaries.

TILED defaults to FALSE.

3.2.3. GetFeatureInfo

Standard parameters for the GetFeatureInfo request according to the OGC WMS 1.1.1 and 1.3.0 specifications:

Parameter	Required	Description
SERVICE	Yes	Name of the service (WMS)
REQUEST	Yes	Name of the request (GetFeatureInfo)
VERSION	No	Version of the service
QUERY_LAYERS	Yes	Layers to query
LAYERS	Yes	Layers to display (identical to QUERY_LAYERS)
STYLES	No	Layers’ style
SRS / CRS	Yes	Coordinate reference system
BBOX	No	Map extent
WIDTH	Yes	Width of the image in pixels
HEIGHT	Yes	Height of the image in pixels
TRANSPARENT	No	Transparent background
INFO_FORMAT	No	Output format
FEATURE_COUNT	No	Maximum number of features to return
I	No	Pixel column of the point to query
X	No	Same as I parameter, but in WMS 1.1.1
J	No	Pixel row of the point to query
Y	No	Same as J parameter, but in WMS 1.1.1
WMS_PRECISION	No	The precision (number of digits) to be used when returning geometry (see how to add geometry to feature response). The default value is `-1` meaning that the precision defined in the project is used.

In addition to the standard ones, QGIS Server supports the following extra parameters:

Parameter	Required	Description
MAP	Yes	QGIS project file
FILTER	No	Subset of features
FI_POINT_TOLERANCE	No	Tolerance in pixels for point layers
FI_LINE_TOLERANCE	No	Tolerance in pixels for line layers
FI_POLYGON_TOLERANCE	No	Tolerance in pixels for polygon layers
FILTER_GEOM	No	Geometry filtering
WITH_DISPLAY_NAME	No	Add the feature display name to the output
WITH_MAPTIP	No	Add map tips to the output
WITH_GEOMETRY	No	Add geometry to the output

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&VERSION=1.3.0
&REQUEST=GetMap
&MAP=/home/qgis/projects/world.qgs
&LAYERS=mylayer1,mylayer2,mylayer3
&CRS=EPSG:4326
&WIDTH=400
&HEIGHT=400
&INFO_FORMAT=text/xml
&TRANSPARENT=TRUE
&QUERY_LAYERS=mylayer1
&FEATURE_COUNT=3
&I=250
&J=250

INFO_FORMAT

This parameter may be used to specify the format of the result. Available values are:

text/xml
text/html
text/plain
application/vnd.ogc.gml
application/json

QUERY_LAYERS

This parameter specifies the layers to display on the map. Names are separated by a comma.

In addition, QGIS Server introduces options to select layers by:

short name
layer id

See the LAYERS parameter defined in GetMap for more information.

FEATURE_COUNT

This parameter specifies the maximum number of features per layer to return. For example if QUERY_LAYERS is set to layer1,layer2 and FEATURE_COUNT is set to 3 then a maximum of 3 features from layer1 will be returned. Likewise a maximum of 3 features from layer2 will be returned.

By default, only 1 feature per layer is returned.

I

This parameter, defined in WMS 1.3.0, allows you to specify the pixel column of the query point.

X

Same parameter as I, but defined in WMS 1.1.1.

J

This parameter, defined in WMS 1.3.0, allows you to specify the pixel row of the query point.

Y

Same parameter as J, but defined in WMS 1.1.1.

FI_POINT_TOLERANCE

This parameter specifies the tolerance in pixels for point layers.

FI_LINE_TOLERANCE

This parameter specifies the tolerance in pixels for line layers.

FI_POLYGON_TOLERANCE

This parameter specifies the tolerance in pixels for polygon layers.

FILTER_GEOM

This parameter specifies a WKT geometry with which features have to intersect.

WITH_DISPLAY_NAME

This parameter specifies whether to add feature display name to the output.

Available values are (not case sensitive):

TRUE
FALSE

WITH_MAPTIP

This parameter specifies whether to add map tips to the output.

Available values are (not case sensitive):

TRUE
FALSE
HTML_FI_ONLY_MAPTIP: like TRUE, with the difference that the HTML response to the feature info request only contains the maptip. This gives full control over the HTML response using e.g. the built-in layer maptip editor.

WITH_GEOMETRY

This parameter specifies whether to add geometries to the output. To use this feature you must first enable the Add geometry to feature response option in the QGIS project. See Configure your project.

Available values are (not case sensitive):

TRUE
FALSE

3.2.4. GetLegendGraphic

Standard parameters for the GetLegendGraphic request according to the OGC WMS 1.1.1 and 1.3.0 specifications:

Parameter	Required	Description
SERVICE	Yes	Name of the service (WMS)
REQUEST	Yes	Name of the request (GetLegendGraphic)
VERSION	No	Version of the service
LAYERS	Yes	Layers to display
STYLES	No	Layers’ style
SRS / CRS	No	Coordinate reference system
BBOX	No	Map extent
WIDTH	No	Width of the image in pixels
HEIGHT	No	Height of the image in pixels
FORMAT	No	Legend format
TRANSPARENT	No	Transparent background

In addition to the standard ones, QGIS Server supports extra parameters to change the size of the legend elements or the font properties for layer titles and item labels:

Parameter	Required	Description
MAP	Yes	QGIS project file
SRCWIDTH	No	Map width
SRCHEIGHT	No	Map height
SHOWFEATURECOUNT	No	Add feature count of features
RULE	No	Rule symbol to render
RULELABEL	No	Item labels rendering
BOXSPACE	No	Space between legend frame and content (mm)
LAYERSPACE	No	Vertical space between layers (mm)
LAYERTITLESPACE	No	Vertical space between layer title and items (mm)
SYMBOLSPACE	No	Vertical space between symbol and items (mm)
ICONLABELSPACE	No	Horizontal space between symbol and label (mm)
SYMBOLWIDTH	No	Width of the symbol preview (mm)
SYMBOLHEIGHT	No	Height of the symbol preview (mm)
LAYERTITLE	No	Layer title rendering
LAYERFONTFAMILY	No	Layer font family
LAYERFONTBOLD	No	Layer title bold rendering
LAYERFONTSIZE	No	Layer title font size (pt)
LAYERFONTITALIC	No	Layer title italic rendering
LAYERFONTCOLOR	No	Layer title color
ITEMFONTFAMILY	No	Item font family
ITEMFONTBOLD	No	Item label bold rendering
ITEMFONTSIZE	No	Item label font size (pt)
ITEMFONTITALIC	No	Item label italic rendering
ITEMFONTCOLOR	No	Item label color
SHOWRULEDETAILS	No	Adds the rule text to JSON output
ADDLAYERGROUPS	No	Adds the layer groups to JSON output

BBOX

This parameter can be used to specify the geographical area for which the legend should be built (its format is described here) but cannot be combined with the RULE parameter. The SRS/CRS parameter becomes mandatory when using the BBOX parameter.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=countries,airports
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326

Note

When the BBOX parameter is defined, the legend is referred to as a content based legend.

WIDTH

This parameter is not used by default but becomes mandatory when the RULE parameter is set. In this case it allows to specify the width in pixels of the output image.

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=getlegendgraphic
&LAYER=testlayer%20%C3%A8%C3%A9
&RULE=rule1
&WIDTH=30
&HEIGHT=30

HEIGHT

This parameter is not used by default but becomes mandatory when the RULE parameter is set. In this case it allows to specify the height in pixels of the output image.

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYER=testlayer%20%C3%A8%C3%A9
&RULE=rule1
&WIDTH=30
&HEIGHT=30

FORMAT

This parameter may be used to specify the format of legend image. Available values are:

image/jpeg
image/png
application/json

For JSON, symbols are encoded with Base64 and most other options related to layout or fonts are not taken into account because the legend must be built on the client side. The RULE parameter cannot be combined with this format.

URL example with the corresponding JSON output:

http://localhost/qgisserver?
SERVICE=WMS&
REQUEST=GetLegendGraphic&
LAYERS=airports&
FORMAT=application/json

And the corresponding JSON output:

{
  "nodes":[
    {
      "icon":"<base64 icon>",
      "title":"airports",
      "type":"layer"
    }
  ],
  "title":""
}

SRCWIDTH

This parameter may de defined when the RULE parameter is set. In this case, the SRCWIDTH value is forwarded to the underlying GetMap request as the WIDTH parameter while the WIDTH parameter of GetLegendGraphic is used for the image legend size.

SRCHEIGHT

This parameter may de defined when the RULE parameter is set. In this case, the SRCHEIGHT value is forwarded to the underlying GetMap request as the HEIGHT parameter while the HEIGHT parameter of GetLegendGraphic is used for the image legend size.

SHOWFEATURECOUNT

This parameter can be used to activate feature count in the legend. Available values are (not case sensitive):

TRUE
FALSE

For example:

../../../_images/getfeaturecount_legend.png

RULE

This parameter is available on layers with Rule-based rendering and allows to build a legend with only the named rule symbol. It cannot be combined with BBOX parameter. HEIGHT and WIDTH must be specified.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=mylayer,
&RULE=myrulename,
&WIDTH=20,
&HEIGHT=20

RULELABEL

This parameter allows to control the item label rendering. Available values are (not case sensitive):

TRUE: display item label
FALSE: hide item label
AUTO: hide item label for layers with Single symbol rendering

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=countries,airports
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&RULELABEL=AUTO

../../../_images/wms_getlegendgraphic_rulelabel.png — Fig. 3.5 Legend rendering without label for single symbol layers

BOXSPACE

This parameter allows to specify the space between legend frame and content in millimeters. By default, the space value is 2 mm.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=airports
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&BOXSPACE=0

../../../_images/wms_getlegendgraphic_boxspace.png — Fig. 3.6 To the left `BOXSPACE=0` and to the right `BOXSPACE=15`

LAYERSPACE

This parameter allows to specify the vertical space between layers in millimeters. By default, the space value is 3 mm.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&LAYERSPACE=0

../../../_images/wms_getlegendgraphic_layerspace.png — Fig. 3.7 To the left `LAYERSPACE=0` and to the right `LAYERSPACE=10`

LAYERTITLESPACE

This parameter allows to specify the vertical space between layer title and items following in millimeters. By default the space value is 3 mm.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&LAYERTITLESPACE=0

../../../_images/wms_getlegendgraphic_layertitlespace.png — Fig. 3.8 To the left `LAYERTITLESPACE=0` and to the right `LAYERTITLESPACE=10`

SYMBOLSPACE

This parameter allows to specify the vertical space between symbol and item following in millimeters. By default the space value is 2 mm.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=countries
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&SYMBOLSPACE=0

../../../_images/wms_getlegendgraphic_symbolspace.png — Fig. 3.9 To the left `SYMBOLSPACE=0` and to the right `SYMBOLSPACE=5`

ICONLABELSPACE

This parameter allows to specify the horizontal space between symbol and label text in millimeters. By default the space value is 2 mm.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=getlegendgraphic
&LAYERS=countries,
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&ICONLABELSPACE=0

../../../_images/wms_getlegendgraphic_iconlabelspace.png — Fig. 3.10 To the left `ICONLABELSPACE=0` and to the right `ICONLABELSPACE=10`

SYMBOLWIDTH

This parameter allows to specify the width of the symbol preview in millimeters. By default the width value is 7 mm.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=countries,
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&SYMBOLWIDTH=2

../../../_images/wms_getlegendgraphic_symbolwidth.png — Fig. 3.11 To the left `SYMBOLWIDTH=2` and to the right `SYMBOLWIDTH=20`

SYMBOLHEIGHT

This parameter allows to specify the height of the symbol preview in millimeters. By default the height value is 4 mm.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=countries,
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&SYMBOLHEIGHT=2

../../../_images/wms_getlegendgraphic_symbolheight.png — Fig. 3.12 To the left `SYMBOLHEIGHT=2` and to the right `SYMBOLHEIGHT=6`

LAYERTITLE

This parameter specifies whether to render layer title.

Available values are (not case sensitive):

TRUE (default value)
FALSE

LAYERFONTFAMILY

This parameter specifies the font family to use for rendering layer title.

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=countries
&LAYERFONTFAMILY=monospace

LAYERFONTBOLD

This parameter specifies whether the layer title is rendered in bold. Available values are (not case sensitive):

TRUE
FALSE

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&LAYERFONTBOLD=TRUE

../../../_images/wms_getlegendgraphic_layerfontbold.png — Fig. 3.13 Legend with `LAYERFONTBOLD=TRUE`

LAYERFONTSIZE

This parameter specifies the font size for rendering layer title in point.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&LAYERFONTSIZE=20

../../../_images/wms_getlegendgraphic_layerfontsize.png — Fig. 3.14 Legend with `LAYERFONTSIZE=20`

LAYERFONTITALIC

This parameter specifies whether the layer title is rendered in italic. Available values are (not case sensitive):

TRUE
FALSE

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&LAYERFONTITALIC=TRUE

../../../_images/wms_getlegendgraphic_layerfontitalic.png — Fig. 3.15 Legend with `LAYERFONTITALIC=TRUE`

LAYERFONTCOLOR

This parameter specifies the layer title color. The color may be literal (red, green, ..) or in hexadecimal notation (0xFF0000, 0x00FF00, …).

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&LAYERFONTCOLOR=0x5f9930

../../../_images/wms_getlegendgraphic_layerfontcolor.png — Fig. 3.16 Legend with `LAYERFONTCOLOR=0x5f9930`

ITEMFONTFAMILY

This parameter specifies the font family to use for rendering item label.

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=countries
&ITEMFONTFAMILY=monospace

ITEMFONTBOLD

This parameter specifies whether the item label is rendered in bold. Available values are (not case sensitive):

TRUE
FALSE

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&ITEMFONTBOLD=TRUE

../../../_images/wms_getlegendgraphic_itemfontbold.png — Fig. 3.17 Legend with `ITEMFONTBOLD=TRUE`

ITEMFONTSIZE

This parameter specifies the font size for rendering layer title in point.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&ITEMFONTSIZE=20

../../../_images/wms_getlegendgraphic_itemfontsize.png — Fig. 3.18 Legend with `ITEMFONTSIZE=30`

ITEMFONTITALIC

This parameter specifies whether the item label is rendered in italic. Available values are (not case sensitive):

TRUE
FALSE

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&ITEMFONTITALIC=TRUE

../../../_images/wms_getlegendgraphic_itemfontitalic.png — Fig. 3.19 Legend with `ITEMFONTITALIC=TRUE`

ITEMFONTCOLOR

This parameter specifies the item label color. The color may be literal (red, green, ..) or in hexadecimal notation (0xFF0000, 0x00FF00, …).

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphic
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&ITEMFONTCOLOR=0x5f9930

../../../_images/wms_getlegendgraphic_itemfontcolor.png — Fig. 3.20 Legend with `ITEMFONTCOLOR=0x5f9930`

SHOWRULEDETAILS

This parameter specifies if the JSON output will also contain the details about the rule that generated the legend entry. This parameter only has effect when the renderer is rule-based or categorized.

URL example with the corresponding JSON output:

http://localhost/qgisserver?
SERVICE=WMS&
REQUEST=GetLegendGraphic&
LAYERS=airports&
FORMAT=application/json&
SHOWRULEDETAILS=TRUE

And the corresponding JSON output:

{
  "nodes":[
    {
      "icon":"<base64 icon>",
      "title":"airports",
      "type":"layer",
      "rule": "type = 'airport'"
    }
  ],
  "title":""
}

ADDLAYERGROUPS

This parameter specifies if the JSON output will also display the names of the layers groups (and subgroups) in the legend entry. Possible values are:

TRUE: display the groups labels
FALSE (default): hide the groups labels

../../../_images/wms_getlegendgraphic_addlayergroups.png — Fig. 3.21 Legend without (left) and with (right) layer groups labels display

The corresponding JSON output showing groups name would look like:

{ "nodes":
  [{ "nodes":
     [{ "icon":"iVBORw0KGgoAAAANSUhEUgAAABQAAAAUCAYAAACNiR0NAAAACXBIWXMAABYlAAAWJQFJUiTwAAAAUklEQVQ4jWNgGAXDHzASUqCsrPwfmX/37l28evBKKisr/0+a7IMiNi93C15DcUpgM4wYQ5nwuZAcMIQNvHv3LuO83C0kG0hysoFZRrJNo2AYAQC87BpkGQj1fwAAAABJRU5ErkJggg==",
        "title":"layer_a", "type":"layer"
     },
     { "nodes":
       [{ "icon":"iVBORw0KGgoAAAANSUhEUgAAABMAAAAUCAYAAABvVQZ0AAAACXBIWXMAABYlAAAWJQFJUiTwAAAAHUlEQVQ4jWNgGAWjYCQDxh887r8G2hGjYBQMGAAA1x0CR0FzIkYAAAAASUVORK5CYII=",
          "title":"layer_b", "type":"layer"
        },
        { "icon":"iVBORw0KGgoAAAANSUhEUgAAABMAAAAUCAYAAABvVQZ0AAAACXBIWXMAABYlAAAWJQFJUiTwAAAAHUlEQVQ4jWNgGAWjYCQDxtmzZ/8aaEeMglEwYAAAaIoCzTtn5XoAAAAASUVORK5CYII=",
          "title":"layer_c", "type":"layer"
       }],
       "title":"lines", "type":"group"
     },
     { "icon":"iVBORw0KGgoAAAANSUhEUgAAABMAAAATCAYAAAByUDbMAAAACXBIWXMAABYlAAAWJQFJUiTwAAAAKklEQVQ4jWNUVlX/z0AlwMLAwMDAnXmQKoYxUcWUUcNGDRs1bNSwYWYYACXDAsvQaTuVAAAAAElFTkSuQmCC",
       "title":"layer_d", "type":"layer"
     }],
     "title":"top-level-group", "type":"group"
  }],
  "title":""
}

3.2.5. GetStyle(s)

Standard parameters for the GetStyle (or GetStyles) request according to the OGC WMS 1.1.1 specifications:

Parameter	Required	Description
SERVICE	Yes	Name of the service (WMS)
REQUEST	Yes	Name of the request (GetStyle or GetStyles)
LAYERS	Yes	Layers to query

The GetStyle request supports as well the following vendor parameters:

Parameter	Required	Description
MAP	Yes	QGIS project file

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetStyles
&LAYERS=mylayer1,mylayer2

3.2.6. DescribeLayer

Standard parameters for the DescribeLayer request according to the OGC WMS 1.1.1 and 1.3.0 specifications:

Parameter	Required	Description
SERVICE	Yes	Name of the service (WMS)
REQUEST	Yes	Name of the request (DescribeLayer)
LAYERS	Yes	Layers to describe
SLD_VERSION	Yes	SLD version

The DescribeLayer request supports as well the following vendor parameters:

Parameter	Required	Description
MAP	Yes	QGIS project file

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=DescribeLayer
&SLD_VERSION=1.1.0
&LAYERS=mylayer1

The XML document looks like:

<DescribeLayerResponse xmlns="http://www.opengis.net/sld" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ows="http://www.opengis.net/ows" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:se="http://www.opengis.net/se" xsi:schemaLocation="http://www.opengis.net/sld http://schemas.opengis.net/sld/1.1.0/DescribeLayer.xsd">
    <Version>1.1.0</Version>
    <LayerDescription>
        <owsType>wfs</owsType>
        <se:OnlineResource xlink:href="http://localhost/qgisserver" xlink:type="simple"/>
        <TypeName>
            <se:FeatureTypeName>my_vector_layer</se:FeatureTypeName>
        </TypeName>
    </LayerDescription>
    <LayerDescription>
        <owsType>wcs</owsType>
        <se:OnlineResource xlink:href="http://localhost/qgisserver" xlink:type="simple"/>
        <TypeName>
            <se:FeatureTypeName>my_raster_layer</se:FeatureTypeName>
        </TypeName>
    </LayerDescription>
</DescribeLayerResponse>

SLD_VERSION

This parameter allows to specify the version of SLD. Only the value 1.1.0 is available.

3.2.7. GetPrint

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

The GetPrint request supports redlining, external WMS layers as well as the following parameters:

Parameter	Required	Description
MAP	Yes	QGIS project file
SERVICE	Yes	Name of the service (WMS)
REQUEST	Yes	Name of the request (GetPrint)
VERSION	No	Version of the service
LAYERS	No	Layers to display
TEMPLATE	Yes	Layout template to use
SRS / CRS	Yes	Coordinate reference system
FORMAT	No	Output format
FORMAT_OPTIONS	No	Options of the specified file format Only for `FORMAT=application/pdf`
ATLAS_PK	No	Atlas features
STYLES	No	Layers’ style
TRANSPARENT	No	Transparent background
OPACITIES	No	Opacity for layer or group
SELECTION	No	Highlight features
mapX:EXTENT	No	Extent of the map ‘X’
mapX:LAYERS	No	Layers of the map ‘X’
mapX:STYLES	No	Layers’ style of the map ‘X’
mapX:SCALE	No	Layers’ scale of the map ‘X’
mapX:ROTATION	No	Rotation of the map ‘X’
mapX:GRID_INTERVAL_X	No	Grid interval on x axis of the map ‘X’
mapX:GRID_INTERVAL_Y	No	Grid interval on y axis of the map ‘X’

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&VERSION=1.3.0
&REQUEST=GetPrint
&MAP=/home/qgis/projects/world.qgs
&CRS=EPSG:4326
&FORMAT=png
&TEMPLATE=Layout%201
&map0:EXTENT=-180,-90,180,90
&map0:LAYERS=mylayer1,mylayer2,mylayer3
&map0:OPACITIES=125,200,125
&map0:ROTATION=45

Note that the layout template may contain more than one map. In this way, if you want to configure a specific map, you have to use mapX: parameters where X is a positive number that you can retrieve thanks to the GetProjectSettings request.

For example:

<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>

TEMPLATE

This parameter can be used to specify the name of a layout template to use for printing.

FORMAT

This parameter specifies the format of map image. Available values are:

png (default value)
image/png
jpg
jpeg
image/jpeg
svg
image/svg
image/svg+xml
pdf
application/pdf

If the FORMAT parameter is different from one of these values, then an exception is returned.

FORMAT_OPTIONS

This parameter can be used to specify options for the selected format. Only for FORMAT=application/pdf in GetPrint requests. Takes a list of key:value pairs separated by semicolon:

RASTERIZE_WHOLE_IMAGE: whether the whole pdf should be exported as an image. Default: false.
FORCE_VECTOR_OUTPUT: whether pdf should be exported as vector. Default: false.
APPEND_GEOREFERENCE: whether georeference info shall be added to the pdf. Default: true.
EXPORT_METADATA: whether metadata shall be added to the pdf. Default: true.
TEXT_RENDER_FORMAT: sets the text render format for pdf export. It can be AlwaysOutlines (default) or AlwaysText.
SIMPLIFY_GEOMETRY: whether features geometries shall be simplified. Default: true.
WRITE_GEO_PDF: whether a Geospatial PDF shall be exported. Default: false.
USE_ISO_32000_EXTENSION_FORMAT_GEOREFERENCING: whether Iso32000 georeferencing shall be used. Default: false.
USE_OGC_BEST_PRACTICE_FORMAT_GEOREFERENCING: whether OGC best practice georeferencing shall be used. Default: false.
EXPORT_THEMES: a comma separated list of map themes to use for a Geospatial PDF export
PREDEFINED_MAP_SCALES: a comma separated list of map scales to render the map
LOSSLESS_IMAGE_COMPRESSION: whether images embedded in pdf must be compressed using a lossless algorithm. Default: false.
DISABLE_TILED_RASTER_RENDERING: whether rasters shall be untiled in the pdf. Default: false.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&VERSION=1.3.0
&REQUEST=GetPrint
&MAP=/home/qgis/projects/world.qgs
&CRS=EPSG:4326
&FORMAT=pdf
&TEMPLATE=Layout%201
&FORMAT_OPTIONS=FORCE_VECTOR_OUTPUT:TRUE;TEXT_RENDER_FORMAT:AlwaysOutlines;PREDEFINED_MAP_SCALES:250

ATLAS_PK

This parameter allows activation of Atlas rendering by indicating which features we want to print. In order to retrieve an atlas with all features, the * symbol may be used (according to the maximum number of features allowed in the project configuration).

When FORMAT is pdf, a single PDF document combining the feature pages is returned. For all other formats, a single page is returned.

mapX:EXTENT

This parameter specifies the extent for a layout map item as xmin,ymin,xmax,ymax.

mapX:ROTATION

This parameter specifies the map rotation in degrees.

mapX:GRID_INTERVAL_X

This parameter specifies the grid line density in the X direction.

mapX:GRID_INTERVAL_Y

This parameter specifies the grid line density in the Y direction.

mapX:SCALE

This parameter specifies the map scale for a layout map item. 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.

mapX:LAYERS

This parameter specifies the layers for a layout map item. See GetMap Layers for more information on this parameter.

mapX:STYLES

This parameter specifies the layers’ styles defined in a specific layout map item. See GetMap Styles for more information on this parameter.

3.2.8. GetProjectSettings

This request type works similar to GetCapabilities, but it is more specific to QGIS Server and allows a client to read additional information which are 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
show if a group in the layer tree is mutually exclusive

The GetProjectSettings request supports the following parameters:

Parameter	Required	Description
MAP	Yes	QGIS project file
SERVICE	Yes	Name of the service (WMS)
REQUEST	Yes	Name of the request (GetProjectSettings)

3.2.9. GetSchemaExtension

The GetSchemaExtension request allows to retrieve optional extended capabilities and operations of the WMS service such as implemented by QGIS Server.

Parameter	Required	Description
MAP	Yes	QGIS project file
SERVICE	Yes	Name of the service (WMS)
REQUEST	Yes	Name of the request (GetSchemaExtension)

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetSchemaExtension

The XML document looks like:

<schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:wms="http://www.opengis.net/wms" xmlns:qgs="http://www.qgis.org/wms" targetNamespace="http://www.qgis.org/wms" elementFormDefault="qualified" version="1.0.0">
    <import namespace="http://www.opengis.net/wms" schemaLocation="http://schemas.opengis.net/wms/1.3.0/capabilities_1_3_0.xsd"/>
    <element name="GetPrint" type="wms:OperationType" substitutionGroup="wms:_ExtendedOperation"/>
    <element name="GetStyles" type="wms:OperationType" substitutionGroup="wms:_ExtendedOperation"/>
</schema>

3.2.10. External WMS layers

QGIS Server allows including layers from external WMS servers in WMS GetMap and WMS GetPrint requests. This is especially useful if a web client uses an external background layer in the web map. For performance reasons, such layers should be directly requested by the web client (not cascaded via QGIS server). For printing however, these layers should be cascaded via QGIS server in order to appear in the printed map.

External layers can be added to the LAYERS parameter as EXTERNAL_WMS:<layername>. The parameters for the external WMS layers (e.g. url, format, dpiMode, crs, layers, styles) can later be given as service parameters <layername>:<parameter>. In a GetMap request, this might look like this:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&LAYERS=EXTERNAL_WMS:basemap,layer1,layer2
&OPACITIES=100,200,255
&STYLES=,,
&basemap:url=http://externalserver.com/wms.fcgi
&basemap:format=image/jpeg
&basemap:dpiMode=7
&basemap:crs=EPSG:2056
&basemap:layers=orthofoto
&basemap:styles=default

Similarly, external layers can be used in GetPrint requests:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetPrint
&TEMPLATE=A4
&map0:layers=EXTERNAL_WMS:basemap,layer1,layer2
&map0:EXTENT=<minx,miny,maxx,maxy>
&OPACITIES=100,200,255
&basemap:url=http://externalserver.com/wms.fcgi
&basemap:format=image/jpeg
&basemap:dpiMode=7
&basemap:crs=EPSG:2056
&basemap:layers=orthofoto
&basemap:styles=default

3.2.11. 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 GetMap request is in the format:

http://localhost/qgisserver?
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

The GetPrint equivalent is in the format (note that mapX: parameter is added to tell which map has redlining):

http://localhost/qgisserver?
SERVICE=WMS
&VERSION=1.3.0
&REQUEST=GetPrint
&map0:HIGHLIGHT_GEOM=POLYGON((590000 5647000, 590000 6110620, 2500000 6110620, 2500000 5647000, 590000 5647000))
&map0: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>
&map0:HIGHLIGHT_LABELSTRING=Write label here
&map0:HIGHLIGHT_LABELSIZE=16
&map0:HIGHLIGHT_LABELCOLOR=%23000000
&map0:HIGHLIGHT_LABELBUFFERCOLOR=%23FFFFFF
&map0: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:

../../../_images/server_redlining.png — Fig. 3.22 Server response to a GetMap request with redlining parameters

You can see there are several parameters in this request to control the redlining feature. The full list includes:

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_LABELBUFFERCOLOR: This parameter controls the label buffer color.
HIGHLIGHT_LABELBUFFERSIZE: This parameter controls the label buffer size.
HIGHLIGHT_LABELCOLOR: This parameter controls the label color.
HIGHLIGHT_LABEL_DISTANCE: controls the distance between feature (e.g. point or line) and the label in mm
HIGHLIGHT_LABELFONT: This parameter controls the font of the label (e.g. Arial)
HIGHLIGHT_LABEL_HORIZONTAL_ALIGNMENT: places the label horizontally on a point using the specified alignment (e.g. ‘left’, ‘center’, ‘right’)
HIGHLIGHT_LABEL_ROTATION: controls the label rotation in degrees
HIGHLIGHT_LABELSIZE: This parameter controls the size of the label.
HIGHLIGHT_LABELSTRING: You can pass your labeling text to this parameter.
HIGHLIGHT_LABEL_VERTICAL_ALIGNMENT: places the label vertically on a point using the specified alignment (e.g. ‘top’, ‘half’, ‘bottom’)
HIGHLIGHT_SYMBOL: This controls how the geometry is outlined and you can change the stroke width, color and opacity.