WMS Server

Owned by Shaun Forbes
Last updated: 31 Aug, 2022
4 min read

This update exposes Weave map engines as a WMS service. The bundle can also be used to create URL's that can be called from external applications to create custom map images. The bundle supports additional parameters beyond those required by WMS and allows for more customised map output.

A new configuration describes a map context that is similar to that which is setup for a map view in a client configuration. It is generated in a similar way to the maps that are included in a BIRT report.

There can be multiple map context setups, that each describe different map setups.

<?xml version="1.0" encoding="UTF-8"?>

<config xmlns="urn:com.cohga.server.config#1.0" xmlns:wmsserver="urn:com.cohga.server.wms#1.0">

	<wmsserver:context id="test">
		<mapengine id="mapengine.raster">
			<layer>satellite</layer>
		</mapengine>
		<mapengine id="mapengine.vector">
			<layer>property</layer>
			<layer>road</layer>
			<layer>suburb</layer>
			<layer>mccbound</layer>
		</mapengine>
		<mapengine id="mapengine.parks" opacity="0.75">
			<layer>Reserve Images</layer>
		</mapengine>
	</wmsserver:context>

</config>

The above example exposes a new WMS service at /weave/wms/test that will contain the layers listed (and only those layers).
When the WMS client tries to draw the map, Weave will use the three map engines to generate the individual images and combine them into a single map image to return to the client.
This service should be supported in any WMS compliant client.

Complete option list

Name

Description

WMS Compliant

srs

Coordinate reference system of the coordinates specified in the URL

Y

width

Width of generated image in pixels

Y

height

Height of generated image in pixels

Y

format

Output format of the generated image

Y

bgcolor

Background colour

Y

transparent

true if transparent images should be created, false if opaque images should be generated

Y

bbox

Comma separated minx, miny, maxx and maxy of the generated image

Y

layers

List of layers to draw, all layers will be drawn if not set at all, and no layers drawn if layers is set to no value

Y

exceptions

Method used to return errors to the caller


exceptionmessageThe error message to draw on the map if an image can not be generated

size

Comma separated width and height of generated image in pixels


dpi

DPI of generated image, to ensure scale dependencies are calculated correctly


minx

Left X coordinate


miny

Bottom Y coordinate


maxx

Right X Coordinate


maxy

Top Y coordinate


x

Center X coordinate


y

Center Y coordinate


center

Comma separated X and Y coordinate. Both center and centre are supported


scale

Scale to generate map at


entity

Entity to use to determine map extent and draw highlight


ids

Identifiers of entities to zoom to and highlight


filter

Filters to be applied to 'ids' before calculating the extent. For use if external system uses different id's for the underlying GIS data


buffer

Amount to scale entity extent by to calculate extent, e.g. 1.2 to place a 20% buffer around the entity bounds


minscale

Minimum scale to zoom to when zooming to an entity


highlight

false if the entity highlight should not be drawn, true if it should be drawn


hlcolor

Vector highlight colour


mcolorMarker highlight colour. Should be blue, brown, dark, green, orange, purple, red, silver or yellow. The default is green. The mcolor 'dark' is a dark grey.

 

You must include a parameter or parameters in the URL to set or calculate the map bounding box, this can not be set in the context.

When specifying the map bounding box setting minx, miny, maxx and maxy is the same as specifying just bbox, and bbox will take precedence if both are present.
If a bounding box is set it will take precedence over setting the map extent based on a center x,y and scale.
If a center x, y and scale are set they will take precedence over the entity and ids.

Setting size will take precedence over setting width and height if both are present.

The above settings will generally be supplied by the WMS client, and defaults can be set in the context.
Generally these will all be set by the WMS client when sending WMS requests to the Weave server and do not need to be specified in the configuration, however, you may want to set these values in the configuration if you're intending on constructing and using the URL's from another application and you want to simplify the URL that the other application needs to use.
For example, if you have an application that you want to always generate an 800x800 PNG image with a light blue background then you could use the URL:
/weave/wms/test?width=800&height=800&bgcolor=0x7f7fff&format=png&bbox=140,-36,141,-35
or you could set width, height, format and bgcolor in the context and use the following URL instead
/weave/wms/test?bbox=140,-36,141,-35
This allows you to provide a simplified URL to the application provider while specifying the fixed settings yourself, it all depends upon the requirements of the other application and how much of it can be pre-set.

Basic Context Example Requests

These example assume the above example map context

Generate a map at a given extent
/weave/wms/test?maxx=355971&maxy=5831675&minx=323098&miny=5807358&width=800&height=600&format=png32
/weave/wms/test?bbox=323098,580735,355971,5831675&size=800,600&format=png32
Generate a map at a given location
/weave/wms/test?x=355971&y=5831675&scale=5000&width=800&height=600&format=png32
/weave/wms/test?center=355971,5831675&scale=5000&size=800,600&format=png32
Generate a map at a given property
/weave/wms/test?entity=property&ids=242765&minscale=2500&buffer=1.2&width=800&height=600&format=png32
Generate a map at a given property and not highlighting the property
/weave/wms/test?entity=property&ids=242765&minscale=2500&buffer=1.2&highlight=false&width=800&height=600&format=png32
Generate a map at a given location and just highlight a property
/weave/wms/test?x=355971&y=5831675&scale=5000&entity=property&ids=242765&minscale=2500&buffer=1.2&width=800&height=600&format=png32

Extended Context Example Requests

The following examples assume the following map context and are the equivalent of the above.

<?xml version="1.0" encoding="UTF-8"?>

<config xmlns="urn:com.cohga.server.config#1.0" xmlns:wmsserver="urn:com.cohga.server.wms#1.0">
	<wmsserver:context id="test">
		<minscale>2500</minscale>
		<buffer>1.2</buffer>
		<width>800</width>
		<height>600</height>
		<format>png32</format>
		<entity>property</entity>
		<mapengine id="mapengine.raster">
			<layer>satellite</layer>
		</mapengine>
		<mapengine id="mapengine.vector">
			<layer>property</layer>
			<layer>road</layer>
			<layer>suburb</layer>
			<layer>mccbound</layer>
		</mapengine>
		<mapengine id="mapengine.parks" opacity="0.75">
			<layer>Reserve Images</layer>
		</mapengine>
	</wmsserver:context>
</config>
Generate a map at a given extent
/weave/wms/test?maxx=355971&maxy=5831675&minx=323098&miny=5807358
/weave/wms/test?bbox=323098,580735,355971,5831675
Generate a map at a given location
/weave/wms/test?x=355971&y=5831675&scale=5000
/weave/wms/test?center=355971,5831675&scale=5000
/weave/wms/test?center=337649.188,5818856.678&scale=1000&srs=EPSG:28355
/weave/wms/test?center=145.1568367,-37.7632155&scale=5000&srs=EPSG:4283
Generate a map at a given property
/weave/wms/test?entity=property&ids=242765
Generate a map at a given road with a min scale of 5000
/weave/wms/test?entity=roads&ids=AS14124&minscale=5000
Generate a map at a centred on given road with a min scale of 5000 showing just the roads and property layers
/weave/wms/test?entity=roads&ids=AS14124&minscale=5000&layers=road,property

The last example specifies the layer as road and property because there's only one road and property layer in all of the map engines. If the layer id was not unique then the layer can be specified by preceding it with the map engine id and a |, e.g. mapengine.vector|roads

Generated image showing highlighted property

Using multiple contexts allows you to setup different maps depending on the target use.