Hi Paolo, On Apr 2, 2012, at 2:31 AM, Paolo Castagna wrote:
> 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 > Thanks I will check out the above! > Does GeoSPARQL requires FILTER functions only? Good question -- I'm still reading through the spec for GeoSPARQL so not sure as of yet. > > At the moment, I have no idea how you would deal with WKT and GML. SIS has a goal of dealing with WKT: https://issues.apache.org/jira/browse/SIS-10 One thing in my mind related to this is the work that I am doing to integrate GDAL into Tika, here: https://issues.apache.org/jira/browse/TIKA-605 If I can get that done up, then I can use it to plug into SIS and load data into the quad tree. > > Also, I have no idea if SIS provides all the necessary spatial capabilities > necessary for a GeoSPARQL implementation. Neither do I, but I know it has a goal of being able to support something like it and that GeoSPARQL is a great use case. I know that SIS provides a Quad Tree implementation that is storable to an index on disk, and that does point/radius and bbox queries, based on data loaded from GeoRSS and is already released in 0.1 format (and is currently being VOTED for the 0.2 release candidate). So it's starting to gain traction and I would love to use this as a case for making SIS more relevant, so that's my intention. > > 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."? I guess we'll have to find out :) > > Does anyone know if there is any GeoSPARQL implementation elsewhere? Nope, I'm not aware of one, but that doesn't say much since I'm new to GeoSPARQL :) Cheers, Chris ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Chris Mattmann, Ph.D. Senior Computer Scientist NASA Jet Propulsion Laboratory Pasadena, CA 91109 USA Office: 171-266B, Mailstop: 171-246 Email: [email protected] WWW: http://sunset.usc.edu/~mattmann/ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Adjunct Assistant Professor, Computer Science Department University of Southern California, Los Angeles, CA 90089 USA ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
