Connect to a WFS service

2024-10-17

A Web Feature Service (WFS) is a web service for querying spatial data that has a standardized API defined by the Open Geospatial Consortium (OGC). The WfsClient class in the spatial IO module lets developers connect to a WFS service and query data from the service.

The WfsClient class supports the following features:

Supported versions: 1.0.0, 1.1.0, and 2.0.0
Supported filter operators: binary comparisons, logic, math, value, and bbox.
Requests are made using HTTP GET only.

Supported operations:

Operation	Description
GetCapabilities	Generates a metadata document with valid WFS operations and parameters
GetFeature	Returns a selection of features from a data source
DescribeFeatureType	Returns the supported feature types

Using the WFS client

The atlas.io.ogc.WfsClient class in the spatial IO module makes it easy to query a WFS service and convert the responses into GeoJSON objects. This GeoJSON object can then be used for other mapping purposes.

Supported filters

The specification for the WFS standard makes use of OGC filters. The WFS client supports the following filters, assuming that the service being called also supports these filters. Custom filter strings can be passed into the CustomFilter class.

Logical operators

And
Or
Not

Value operators

GmlObjectId
ResourceId

Math operators

Add
Sub
Mul
Div

Comparison operators

PropertyIsEqualTo
PropertyIsNotEqualTo
PropertyIsLessThan
PropertyIsGreaterThan
PropertyIsLessThanOrEqualTo
PropertyIsGreaterThanOrEqualTo
PropertyIsLike
PropertyIsNull
PropertyIsNil
PropertyIsBetween

WFS service explorer

The WFS service explorer sample is a simple tool for exploring WFS services on Azure Maps. For the source code for this sample, see WFS service explorer source code.

To access WFS services hosted on non-CORS enabled endpoints, a CORS enabled proxy service can be passed into the proxyService option of the WFS client as shown in the following example.

//Create the WFS client to access the service and use the proxy service settings
client = new atlas.io.ogc.WfsClient({
    url: url,
    proxyService: window.location.origin + '/YourCorsEnabledProxyService.ashx?url='
});