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A fork of CQELS (Continuous Query Evaluation over Linked Data)

Home Page: https://code.google.com/p/cqels/

License: GNU Lesser General Public License v3.0

Java 100.00%
rdf stream-processing

cqels's People

Contributors

garayzuev avatar kmax avatar

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Watchers

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Forkers

garayzuev jpcik eschwert eugenesiow rita-zgheib

cqels's Issues

Performance of BIND

Running the CQELS engine with a query that requires a BIND drastically reduces performance. For example, the query:

CONSTRUCT { [] ?p ?o . }
WHERE {
   STREAM <http://example.org/stream> [RANGE 1s] {
      ?s ?p ?o .
   }
}

is many times faster than:

CONSTRUCT { ?bnode ?p ?o . }
WHERE {
   STREAM <http://example.org/stream> [RANGE 1s] {
      ?s ?p ?o .
   }
   BIND(BNODE() AS ?bnode)
}

In my particualr use-case the latter form introduced an extra 250-350 ms delay per result. Is there an explanation for why BIND is so slow?

Also, the first query seems to reuse the same blank node for all evaluations: is this the expected behavior?

It's not possible to unregister a continuous query (select or construct)

We call ExecContext.registerSelect(String) or ExecContext.registerConstruct(String) to register a continuous query, but there is no API that could unregister it.

Implement two methods in ExecContext:

  • ExecContext.unregisterSelect(ContinuousSelect)
  • and ExecContext.unregisterConstruct(ContinuousConstruct).

Compile Error in HeuristicRoutingPolicy

The following method is causing a compile error:

    @Override
    public void removeRouter(OpRouter from, OpRouter to) {
        next.remove(from.getId(), to);
    }

next is a HashMap that takes only one parameter to remove an element.

Where is the main-class?

hello, i am really appreciate that the code you just share with us.
but i am really confused that i don't find the main function?
how could i do the experiments?
And also i download the csparqls.jar at the google code, in the MANIFEST.MF, it says the main-class: eu.larkc.csparql.readytogopack.CSPARQL,while couldn't find it in the source file.
Thanks for your help.

Performance of CQELS

Hi,

In your tests, you didn't use any extensive data sets, and I was wondering If you have any concrete performance measures for large amount of data sets. Cheers

Update httpclient

Need to update version of the dependency with groupId org.apache.httpcomponents and artifactId httpclient on 4.3.1 from 4.2.6. You see error if you added a new Test to RemoteSPARQLEndpoint, e.g.:

@Test
public void simpleRemoteTest(){
    final String rmtService = "http://dbpedia.org/sparql";
    RDFStream stream = new DefaultRDFStream(context, STREAM_ID_PREFIX);

    ContinuousSelect query = context.registerSelect(""
            +"PREFIX rdf:<http://www.w3.org/1999/02/22-rdf-syntax-ns#>"
            + "SELECT ?x ?y ?z ?p WHERE {"
            + "STREAM <" + STREAM_ID_PREFIX + "> [NOW] {?x ?y ?z}"
            + "SERVICE <"+rmtService+"> { ?x rdf:type ?p} "                
            + "}");

    SelectAssertListener listener = new SelectAssertListener();
    query.register(listener);

    stream.stream(new Triple(
            Node.createURI("http://www.w3.org/2002/07/owl#inverseOf"),                
            Node.createURI("http://example.org/ontology#hasValue"),
            Node.createLiteral("123")));
    List<Mapping> mappings = await().until(listener, hasSize(1));
    List<Node> nodes = Helpers.toNodeList(context, mappings.get(0));

    Helpers.print(context, mappings);
    assertEquals("http://www.w3.org/2002/07/owl#inverseOf", nodes.get(0).getURI());
    assertEquals("http://example.org/ontology#hasValue",
            nodes.get(1).getURI());
    assertEquals("123", nodes.get(2).getLiteralValue());
    assertEquals("http://www.w3.org/1999/02/22-rdf-syntax-ns#Property", nodes.get(3).getURI());
}

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