Yes - this sounds very interesting. I can help with moving this forward,
as either contribution or extending project. There is something to be
said for starting separately (release is not coupled to Jena release
cycles) then contribute if you want to go that route.
It would be useful whether it has index support or not.
JTS now that is available under EDL form is OK. IIRC when jena-spatial
was done, it was LGPL so it had to be an optional extra.
The LGPL for GeoTools is something to work on but it can be done.
Is there anything in the Eclipse location domain that can provide some
of what GeoTools is used for? If so, geotools can be an optional extra
which is the normal way to deal with the situation.
Andy
Someone recently collected all the Apache projects logos and created the
"powered by" versions:
https://www.apache.org/logos/comdev-test/poweredby/jena.png
On 24/08/18 19:38, ajs6f wrote:
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 <[email protected]> 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: [email protected]
(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
