Created: 23 May 2024

The DSP has always taken a standards-based approach to sharing spatial data to ensure Open Data can be used by as wide an audience as possible. When the platform was established, an assessment was made of available standards and the decision was taken to adopt the Open Geospatial Consortium Standards as they are widely supported by both Free and Open-Source Software and Proprietary GIS software packages.

Initially, two standards were identified for use on the DSP, Web Feature Service (WFS) and Web Map Service (WMS). These standards were identified and adopted to meet the needs of the Open Data community at the time, with most users accessing the data through desktop GIS or Web Mapping applications. Since the Platform was established, technology has evolved and the way that applications and users want to access and use data is changing and will continue to change. These changes are reflected in the standards being developed by the OGC, in keeping with the DSP mission to make Open Data as widely available for re-use as possible, the decision has been taken to adopt the newer OGC API and Web Map Tile Service (WMTS) standards, alongside the existing WFS and WMS services and the recently implemented Web Coverage Services (WCS). OGC GeoPackages are now also available for request Large Data Download and shall be further implemented across the DSP. GeoPackage is the latest development in open, geospatial formats and better support transfer of data for download.  This approach will support changing working practices and keeps the DSP aligned with other data providers.

 More information on the OGC can be found here; Home - Open Geospatial Consortium (ogc.org)

I already use your existing Web Services; do I need to do anything different?

No, where OGC Web Services are currently available they will continue to be available.

I’m confused, which standard should I use?

Below is some guidance to help you decide which standard is the right one for you to use, we would always recommend consulting the documentation for the software that you are using to access the data on the DSP in a way to best meet your needs.

WMS

If you are uncertain where to start, selecting a WMS is a good option, especially if your main requirement is to view data, which can be done instantly using the Preview option on the DSP.  If you are creating a map or web map, a WMS will allow you to view data that has already been styled and can be added directly into your map/web map without requiring further configuration.  This option should be the easiest to use and requires the least configuration.

WMTS

The DSP has initially implemented WMTS where WMS exist for large Survey datasets. Further WMTS services are scheduled to be introduced where relevant for data currently served as a WMS. WMTS should be used where short response times are and if you want to make use of a pre-rendered map tiles or images and can be used in the same way as WMS.

WFS

If you want to interact with the data from the DSP in your GIS or Web Application, for example, query the data or use data to create spatial queries (for example, where is my nearest SSSI?), then we would suggest using the WFS option.

Most software will allow you to add a WFS using a URL, allowing you to immediately view and use the data, but it should be noted that there are a range of configuration options that can applied to a WFS and these should be considered as they can improve the performance of applications using WFS and therefore improve the end user’s experience. How these options are applied, will depend on the software that you are using to access the WFS, but we would suggest using bounding boxes and filters to make a targeted set of data available, as this will improve performance (speed).

Guidance is available at: How Do I Use WFS Layers?

WCS

Web Coverage Service (WCS) defines an interface allowing a client to retrieve unrendered geospatial ‘coverages’. A coverage contains digital geospatial information that are returned as grid values (e.g. as a GeoTIFF file). A WCS provides geospatial information in forms that are useful as multi-valued coverages, for client-side rendering. 

As with WMS and WFS service instances, a WCS allows clients to choose portions of a server's information holdings based on spatial constraints and other query criteria. Unlike WMS (which portrays spatial data to return static maps, rendered as pictures by the server), the Web Coverage Service:

• Provides data together with their detailed descriptions;

• Defines a rich syntax for requests against these data; and

• Returns data with its original semantics (instead of pictures) which may be interpreted, extrapolated, etc., and not just portrayed.

Unlike the WFS (which returns discrete geospatial features), the Web Coverage Service returns coverages representing space-varying phenomena that relate a spatial-temporal domain to a range of properties (possibly multi-dimensional).

Guidance is available at: How can I use WCS Elevation Services?

OGC API

This was developed by the OGC as a progression from the WFS standard and can be used like a WFS, but also lends itself to being used for the development of applications. The move to an API based approach gives more flexibility around how data can be used and accessed and is consistent with non-spatial data approaches. If you are building a Web Mapping Application, including the display of data from the DSP, a WFS may still meet your needs, but you may want to consider trying both.

As with WMS and WFS most GIS applications now support the use of OGC API’s directly, including Esri products. As with the WFS, to get the best performance, we recommend using parameters to refine the data being returned from the DSP.

OGC API Features are available now, for all existing WFS services using the standard, DSP naming convention applying the suffix of ‘/ogc/features/v1’. For example, users can use the equivalent OGC API service by updating the service url:

The Historic Flood Map WFS is published as: https://environment.data.gov.uk/spatialdata/historic-flood-map/wfs

The equivalent OGC API is published as: https://environment.data.gov.uk/spatialdata/historic-flood-map/ogc/features/v1

Further background and guidance available here: