The WSTIERIA project recently participated in a webinar which showcased a number of different approaches to federating access to geospatial (OGC) web services. An OGC press release describes the event and its potential significance for future access to (inter) national geospatial data in Europe.
We presented the facade approach developed previously, demonstrating single sign-on from an unmodified desktop GIS client application (QGIS), to two separate OGC Web Map Services (WMS), with authentication taking place separately in a standard browser. These were unmodified services, with access controlled by IP address in one case and a developer API key in the other. Two facades were put up for the event, additionally enabling federated access to these services.
It was interesting to see the range of other approaches that were presented. A number of commercial vendors demonstrated prototype versions of their desktop GIS client offerings, modified to forward authentication requests from web services (via the ECP protocol or otherwise) to an identity provider selected from those listed in a given federation's metadata by using a built-in graphical user interface. In several cases, the authentication forwarding was based on template open-source Java software developed by Andrew Seales and others in the EDINA geospatial team. One participant demonstrated access to federated web services from unmodified desktop clients by means of a facade application locally installed on the client system, which proxies federated services to plain HTTP localhost-only ports (a flexible approach we also considered earlier in WSTIERIA).
Many thanks to Chris Higgins of the EDINA geospatial team for inviting WSTIERIA to take part in this event. He is involved both in WSTIERIA and in the OGC Interoperability Experiment and EDSIN projects described in the press release.