Greg-- That sounds like a great contribution, although it might indeed make a lot of sense as a sidecar module, or even built up as a package with Fuseki and jena-spatial. Are your modules "pure" functions (i.e. agnostic to backend) or do they take advantage of Jena's spatial index module?
JTS is Eclipse-licensed [1], which (IIUC) should be cool, but GeoTools seems to use LGPL [2], which I believe may present some problems for Jena (which is, of course, licensed as Apache 2.0). ajs6f [1] https://github.com/locationtech/jts/blob/master/LICENSES.md [2] http://docs.geotools.org/latest/userguide/faq.html#q-what-licence-does-geotools-use > On Aug 24, 2018, at 2:14 PM, Greg Albiston <greg_albis...@hotmail.com> wrote: > > Hello, > > Since the topic has come up. I've put together an implementation of all the > GeoSPARQL modules which I was getting around to discussing contributing. > > It has dependencies on JTS, for spatial relations and distances etc., and > GeoTools, for coordinate reference system conversions. I think the remainder > are Apache dependencies. > > The only item to implement was additional unit tests. > > Would this be suitable for incorporating into Jena or better as an extending > project? > > Also, the GeoSPARQL function namespace mentioned by the OP seems incorrect. > The published namespace is: > > geof: http://www.opengis.net/def/function/geosparql/ > > Thanks, > > Greg > > > From: Andy Seaborne > Sent: Friday 24 August, 18:29 > Subject: Re: Spatial distance in Fuseki > To: users@jena.apache.org > > > (PS JENA-664 is the open JIRA for GeoSPARQL) A complete example with imports > etc: https://gist.github.com/afs/a8dfe6680324110bdb675190f9c73035 and also > below. This is for doing everything in one java program. It is the simplest > way and runs in an IDE for debugging. > My main problems in understandig are: > > - where to put the java code and how to name it It will have a URI name. > From the example below: // Register the function FunctionRegistry ref = > FunctionRegistry.get(); ref.put("http://my/num";, MyFunction.class); using the > global function registry (you can have one uique to the dataset if you want > as well but the joy of globally unique URIs is that putting it the > JVM-registry just works. > - how to include it with Fuseki The example below > is the simplest way using embedded Fuseki. It's a plain Java program and > avoids the need to repack jar files which for development makes things easier > and can be debugged in an IDE. If you want to create a packaged standalone > jar file, this is a a template: "basic" is a standalone jar using embedded > Fuseki and with a command line interface. > https://github.com/apache/jena/tree/master/jena-fuseki2/jena-fuseki-basic It > makes: > http://jena.apache.org/documentation/fuseki2/fuseki-embedded.html#fuseki-basic > so using that, adding your own code and making the command line start > register the function should work. > - how to call it in the SPARQL query > Functions are invoked like: (?Z) which is URI + arguments. The URI can a > prefixed name as well; prefixes and expanded during parsing and it is the URI > that matters. BIND ((?Z) AS ?X ) FILTER((?Z) = "number") Andy > ------------------------ > https://gist.github.com/afs/a8dfe6680324110bdb675190f9c73035 and with slight > reformatting: public class FuFunctionEx { /** Our function */ public static > class MyFunction extends FunctionBase1 { @Override public NodeValue > exec(NodeValue v) { if ( v.isNumber() ) return > NodeValue.makeString("number"); return NodeValue.makeString("not a number"); > } } public static void main(String...a) { FusekiLogging.setLogging(); // > Register the function FunctionRegistry ref = FunctionRegistry.get(); > ref.put("http://my/num";, MyFunction.class); int PORT = > FusekiLib.choosePort(); // Some empty dataset DatasetGraph dsg = > DatasetGraphFactory.createTxnMem(); FusekiServer server = > FusekiServer.create() .setPort(PORT) .add("/ds", dsg) .build(); > server.start(); // Test query. String queryString = StrUtils.strjoinNL( > "SELECT * { " , " VALUES ?Z { 123 'abc'}" , " BIND ((?Z) AS ?X )" ,"}" ); try > { String url = "http://localhost:"+PORT+"/ds";; // Connect to the server and > execute the query. try ( RDFConnection conn = > RDFConnectionFactory.connect(url) ) { // Using Java8 features. > conn.queryResultSet(queryString, ResultSetFormatter::out); // Without Java8 > features try ( QueryExecution qExec = conn.query(queryString) ) { ResultSet > rs = qExec.execSelect(); ResultSetFormatter.out(rs); } } } catch (Exception > ex) { ex.printStackTrace(); } finally { server.stop(); } } } Andy >
