No prefixes can be used at this point

Enable support for:

• Websockets
• Polling HTTP
• File
• Server sent events
• Kafka

Make sure parsed queries with dataset clause create SDS themselves, while queries missing the clause require the registration of the SDS manually in the Taskbuilder.

Hello!

I am trying to install RSP4J using Eclipse Maven project. As soon as I add the dependency to com.github.streamreasoning.rsp4j:yasper:1.0.0 using Maven --> Add Dependency dialog I get the following error message in the pom file: Missing artifact it.polimi.sr.rsp:api:jar:1.0.0
(I have the jitpack.io repository already added. Additionally, I could not find this library anywhere.)

Many thanks in advance for the help.

Valentina

In RSP4J, when I try to use CSPARQLEngineRSP4J with Jena related objects (for example, JenaRDFParsingStrategy), I get below exception.

Exception in thread "main" java.lang.NoSuchMethodError: 'java.lang.Object org.apache.jena.atlas.lib.Cache.getIfPresent(java.lang.Object)'

Code fragment :

CSPARQLEngineRSP4J csparql = new CSPARQLEngineRSP4J();

JenaRDFParsingStrategy parsingStrategy = new JenaRDFParsingStrategy(RDFBase.TTL);

String filePath = "stream.log";
FileSource fileSource = new FileSource(filePath, 100, parsingStrategy);
csparql.register(fileSource);

DataStream outputStream = new DataStreamImpl<>("http://out/stream");
csparql.setSelectOutput(outputStream);

ContinuousQuery<Graph, Graph, Binding, Binding> cq = csparql.parseCSPARQLSelect(some_query);
ContinuousQueryExecution<Graph, Graph, Binding, Binding> cqe = csparql.parseSelect(cq);

fileSource.stream();

Note that CQELSEngineRSP4J works fine with Jena related objects in RSP4J.

Make sure that the window clause in the WHERE clause is processed for one or multiple window clauses containing triple patterns.

Pending tasks for RSP4J:

• Task abstractions
• Publication abstraction
• Mapping support
• RSP-QL query loading
• Window generalization
• Stateless functions (map, filter,..)
• Remove observer pattern
• Write javadoc
• Update wiki
• Write Tests

In RSP4J when we stream triple having data value as double, as shown below, we get an exception.
Please note that we observe this exception when the data value is part of the select query result.

Query:
SELECT ?s ?p ?o
from stream http://test/stream [RANGE 10s STEP 1s]
WHERE {
?s ?p ?o
}

Relevant code fragment :
graph.add(instance.createTriple(instance.createIRI("http://test#S1"), instance.createIRI("http://test#hasValue"), rdf.createLiteral("56.1519", Types.XSD_DOUBLE)));
OR
graph.add(instance.createTriple(instance.createIRI("http://test#S1"), instance.createIRI("http://test#hasValue"), rdf.createLiteral("56.1519", instance.createIRI("http://www.w3.org/2001/XMLSchema#double"))));

Exception:
[com.espertech.esper.Timer-default-1] ERROR com.espertech.esper.core.StatementResultServiceImpl - Unexpected exception invoking listener update method on listener class 'QueryListener' : IllegalArgumentException : Illegal character in path at index 0: "56.1519"^^null
java.lang.IllegalArgumentException: Illegal character in path at index 0: "56.1519"^^null
at java.base/java.net.URI.create(URI.java:906)
at org.apache.commons.rdf.simple.IRIImpl.(IRIImpl.java:33)
at org.apache.commons.rdf.simple.SimpleRDF.createIRI(SimpleRDF.java:82)
at org.streamreasoning.rsp4j.api.RDFUtils.createIRI(RDFUtils.java:48)
at org.streamreasoning.rsp4j.csparql.CSPARQLEngineRSP4J$WrappedSelectListener.update(CSPARQLEngineRSP4J.java:120)

As debugging showed, the problem seems to be in repository/com/github/pbonte/CSPARQL-engine/csparql-sparql-jena/0.9.5.1-pomfix/csparql-sparql-jena-0.9.5.1-pomfix.jar!/eu/larkc/csparql/sparql/jena/JenaEngine.class in evaluateQuery function that is called by repository/com/github/pbonte/CSPARQL-engine/csparql-core/0.9.5.1-pomfix/csparql-core-0.9.5.1-pomfix.jar!/eu/larkc/csparql/core/engine/CsparqlEngineImpl.class in update function on line 437 (RDFTable result = this.sparqlEngine.evaluateQuery(csparqlquery.getSparqlQuery());)

For inspiration look at the jgrapht wiki

In Csparql 1.0, we execute query over data source (static knowledge) as below:

String generalQuery = "SELECT ?val FROM http://localhost:8080/csparql_web_server/demo.rdf "
+ "WHERE {" + rdf.createIRI("http://test#Person") + " " + rdf.createIRI("http://test#hasBrother") + " ?val }";

String updateQuery = "PREFIX : http://www.streamreasoning.org/ontologies/sr4ld2014-onto# "
+ "INSERT DATA "
+ "{ GRAPH http://streamreasoning.org/roomConnection { :room :isConnectedTo :room2 } }";

RDFTable queryResult = engine.evaluateGeneralQueryOverDatasource(generalQuery);
engine.execUpdateQueryOverDatasource(updateQuery);

How do we do similar to above using CSparql 2.0 in RSP4J?

At this point no projections are supported

We had to remove csparql1.0 and cqels from the build process as the maven server for csparql1.0 went down.
We need to fix the dependencies for csparql1.0

Hi,

We have a use case where we use geospatial coordinates and as such I was wondering if you support functions like those of GeoSPARQL (the basic SPARQL engine is not designed to calculate trigonometric functions)?

If not, it seems that you are working with JENA and maybe this module could be not too difficult to integrate:
https://jena.apache.org/documentation/geosparql/index.html

Best,

The UnitTests in the IO packages are forced to time out in the automated build. They should be retaught.

Currently, Task API uses strings to refer to operator names, but it is very error prone

transform this

   TaskAbstractionImpl<Graph, Graph, Binding, Binding> t =
            new TaskAbstractionImpl.TaskBuilder(prefixes)
                    .addS2R(":observations", w1, "window1")
                    .addS2R(":tracing", w2, "window2")
                    .addR2R("window1", bgp)
                    .addR2R("window2", bgp2)
                    .addR2S("out", new Rstream<Binding, Binding>())
                    .addProjectionStrings(List.of("?s","?o","?s2"))
                    .build();

into this

TaskAbstractionImpl<Graph, Graph, Binding, Binding> t =
            new TaskAbstractionImpl.TaskBuilder(prefixes)
                    .addS2R(observationStream, w1)
                    .addS2R(outStream, w2)
                    .addR2R(w1, bgp)
                    .addR2R(w2, bgp2)
                    .addR2S(outStream, new Rstream<Binding, Binding>())
                    .addProjectionStrings(List.of("?s","?o","?s2"))
                    .build();

Currently, in the windowing operator, the tick is used after the report. According to SECRET semantics, tick should define when an operator acts on its input. Thus, the ticker must be brought out of the Windowing operator, and be used to regulate the operator's execution.