Pekka Latvala (National Land Survey of Finland)
Many statistical datasets contain information, such as postal area or municipality codes, through which they can be joined with spatial datasets. The combining of statistical and spatial datasets enable the phenomena in question to be analyzed spatially and visualized on a map interface that can bring new insights. The Table Joining Service (TJS) is a service interface that has been originally standardized by the Open Geospatial Consortium (OGC) in 2010. The TJS can be used for joining attribute data e.g. statistical data with spatial datasets. There is currently an ongoing work in the OGC for updating the TJS standard. The TJS 2.0 specification will be based on a modular core + extensions architecture where the core functionalities can be later extended by providing additional modules. The core module of the new TJS specification will contain functionalities for joining attribute data from csv files either directly with GeoJSON files or with spatial datasets that are available on the server.
The National Land Survey of Finland has developed an application that demonstrates the functionalities of the new TJS specification. It contains an easy-to-use interface and it uses the GeoServer application to create OGC’s WFS and WMS interfaces for the joined datasets. The combined data can be downloaded in various formats via the WFS interface and visualized on a map through the WMS interface. The demo application contains also support for map styling via the OGC’s SLD standard.