WFS Spy is a client application which extracts Web Feature Services' (WFS) metadata. It was developed in 2015 and was my master thesis project in the department of Geodesy & Geoinformation Science at the Techical University of Berlin (TU Berlin) using an old JS stack (vanilla javascrit - es5 in combination with jquery, css, no css framework). This is an approach to rewrite the application using a modern JS stack (React with hooks, Typescript, Bootstrap, SASS, npm) along with unit testing (jest, react-testing-library) and make it also mobile friendly.
WFS information extraction is achieved by querying the service itself and those queries follow Open Geospatial Consortium's (OGC) standards. It was aimed to provide a generic approach to cover as many WFS as possible and bridge gaps between existing service variations.
These variations can be further branched and be found not only in different WFS versions but within one version as well. In order to keep the effort on a reasonable level, it was decided to support versions 2.0.x, thus 2.0.0 and 2.0.2, which are the latest and currently widely used. A large number of services that support versions 2.0.x support also versions 1.x, thus 1.0.0 and 1.1.0, therefore the application can be addressed to them as well. However, there are older services which support only 1.x versions. In that case, meta information cannot currently be extracted for them.
The user will be able to derive WFS metadata regarding the supported FeatureTypes (using either GET or POST methods) via a GetCapabilities request and the attribute names via a DescribeFeatureType request. Following, a GetPropertyValue request will be provided to derive the attribute values. Last, using a GetPropertyValue filter request, it will be possible to derive a desired subset of the attribute values or else acquire further knowledge about the content and distribution of those values, which is the main objective of this thesis.
At this point, the application will not provide geometrical feature manipulation via features' geometry filter extraction. It can be included in a future extension of the application. The application aims explicitly in the extraction and filter of WFS features' values.
| # | WFS Url | Service Id | Accept Versions | Service Provider | Operations Metadata | Filter Capabilities | typenames / FeatureTypeList | valueReferences | individual DescFeatType requests | POST |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | http://daim.lfv.se/geoserver/wfs | 7 | 3 | 9 | 8 | yes all | 36 | yes | yes | yes |
| 2 | http://data.gov.au/geoserver/ballarat-corner-shops/wfs | 7 | 3 | 9 | 11 | yes all | 1 | yes | no | no |
| 3 | http://geoserv.weichand.de:8080/geoserver/wfs | 7 | 3 | 8 | 8 | yes all | 5 | yes | no | yes |
| 4 | http://kls.pria.ee/geoserver/pria_avalik/ows | 7 | 3 | 3 | 8 | yes all | 6 | yes | yes | no |
| 5 | http://sdi.gdos.gov.pl/wfs | 7 | 3 | 3 | 8 | yes all | 16 | yes | no | yes |
| 6 | http://inspire.geop.sazp.sk/geoserver/ows | 7 | 3 | 7 | 8 | yes all | 3 | yes | yes | yes |
| 7 | https://demo.mapserver.org/cgi-bin/wfs | 7 | 3 | 4 | 6 | no functions | 2 | no | no | yes |
| 8 | http://inspire.sthelens.gov.uk/geoserver/ows | 7 | 3 | 6 | 11 | yes all | 4 | yes | no | yes |
| 9 | http://tips.noveltis.com/geoserver/tips/wfs | 7 | 3 | 6 | 11 | yes all | 5 | yes | no | no |
| 10 | http://inspire.dundeecity.gov.uk/geoserver/inspire/wfs | 7 | 3 | 8 | 8 | yes all | 21 | yes | no | yes |
| 11 | http://maps.gns.cri.nz/geology/ows | 7 | 3 | 6 | 8 | yes all | 55 | yes | yes | yes |
| 12 | http://www.geo-spatial.org/geoserver/ows | 7 | 3 | 6 | 8 | yes all | 15 | yes | yes | no |
| 13 | http://stadtplaene.ulm.de/geoserver/geoportalUlm/wfs | 7 | 3 | 7 | 11 | yes all | 32 | yes | no | yes |
| 14 | http://kort.strandnr.dk/geoserver/nobc/wfs | 7 | 3 | 8 | 8 | yes all | 9 | yes | no | yes |
| 15 | http://gis.epa.ie/geoserver/wfs | 7 | 3 | 9 | 8 | yes all | 362 | yes | yes | no |
| 16 | http://mapfog.com/ows | 7 | 3 | 5 | 11 | yes all | 140 | yes | yes | yes |
At the moment the user or the developer has to visit the following page at https://cors-anywhere.herokuapp.com/corsdemo to request temporarily access to the demo server. This allows developers to try out the functionality, to help with deciding on self-hosting or looking for alternatives. You can find more in this thread.
clone the project
select master branch
Navigate to the root folder:
yarn install
yarn start
browser listens to http://localhost:3000 as default port.
npm test
npm run test:coverage
GetPropertyValue Filter get requests can not be made on Chrome (version 87.0.4280.141 & above) and Opera (version:73.0.3856.284 & above) due to this known issue. As a result other browsers should be used to make these requests. It has been tested and works without any issues on Firefox (version 84.0.2) and Safari (version 14.0.2).
The app needs a proxy in order to get data from servers with a different domain from the one used to run WFS Spy. For the first version of the application, the one with the old stack, a proxy written in Perl was used along with local apache configuration to run proxies. For the new stack, the following solutions were tried:
The first was eventually used despite tring other proxies, although restrictions in usage were imposed, because it seems to be the most reliable in terms of getting correct server responses from the servers listed on WFS metadata statistics section. A future goal will be to develop something like a proxy middleware solution in order not to rely on external proxies.
Other solutions can be found in this article.