Hi Chris Mattmann, Chris A (388J) wrote: >> How can you implement the GeoSPARQL spec without (re)using a SPARQL >> query engine (such as ARQ)? > > I need that too :) I just don't understand it as well (and understand the > Any23/Tika > and SIS part better). I'll have to learn Jena it looks like though, you game > to > help me out?
ARQ has a couple of extension points which are useful here: Filter Functions http://incubator.apache.org/jena/documentation/query/extension.html#filter-functions Property Functions http://incubator.apache.org/jena/documentation/query/extension.html#property-functions You can find examples of FILTER functions here: http://svn.apache.org/repos/asf/incubator/jena/Jena2/ARQ/tags/jena-arq-2.9.0-incubating/src/main/java/com/hp/hpl/jena/sparql/function/library/ You can find examples of property functions here: http://svn.apache.org/repos/asf/incubator/jena/Jena2/ARQ/tags/jena-arq-2.9.0-incubating/src/main/java/com/hp/hpl/jena/sparql/pfunction/library/ http://svn.apache.org/repos/asf/incubator/jena/Jena2/LARQ/trunk/src/main/java/org/apache/jena/larq/pfunction/ https://github.com/castagna/GeoARQ/blob/master/src/main/java/org/openjena/geoarq/pfunction/NearbyPropertyFunctionEval.java The GeoSPARQL spec available at http://www.w3.org/2011/02/GeoSPARQL.pdf describes FILTER functions: ogcf:relate, ogcf:distance, ogc:buffer, ogcf:convexHull, ogcf:intersection, ogcf:union, ogcf:difference, ogcf:symDifference, ogcf:envelope and ogcf:boundary Does GeoSPARQL requires FILTER functions only? At the moment, I have no idea how you would deal with WKT and GML. Also, I have no idea if SIS provides all the necessary spatial capabilities necessary for a GeoSPARQL implementation. It is still not clear to me, how a GeoSPARQL implementation would support a use case such as this: "John is in Cardif and he wants to find two or three restaurant close to where he is."? Does anyone know if there is any GeoSPARQL implementation elsewhere? Paolo
