SERVICE fails in empty context.

[afs]

Version

4.6.0-SNAPSHOT

What happened?

Executing a query involving SERVICE with an empty context does not work because there is no default service execution.

@Aklakan - for your improvements in this area, could you please ensure that it executes when the context does not have a setting for ARQConstants.registryServiceExecutors.

Relevant output and stacktrace

public static void main(String...args) {
        FusekiLogging.setLogging();
        FusekiServer server = FusekiServer.create()
                .port(0)
                .add("/ds",  DatasetGraphFactory.empty())
                .start();
        String SERVICE = "http://localhost:"+server.getPort()+"/ds";
        Node expected = NodeFactory.createLiteral("28181", XSDDatatype.XSDinteger);
        String queryString = "SELECT * { SERVICE <"+SERVICE+"> { VALUES ?x { 28181 } } }";
        // Empty context
        Context cxt = new Context();
        //Context cxt = ARQ.getContext().copy();
        RowSet rs = QueryExec.dataset(DatasetGraphFactory.empty())
                .query(queryString)
                .context(cxt)
                .select()
                .materialize();
        assertTrue(rs.hasNext());
        Node n = rs.next().get("x");
        assertEquals(expected, n);
    }

Are you interested in making a pull request?

No response

[Aklakan]

So the rules should be like follows - right?

• empty context → default behavior i.e. http service request should work
• context with present but empty service executor registry → error because no registered executor

[afs]

Yes.

"Empty context" here means no entry for ARQConstants.registryServiceExecutors. The rest of the context is not important.

This is motivated by the work elsewhere dealing with the context for query execution (other registries).

1. There is already a separate flag to turn SERVICE off completely.
2. "No entry" should give some default SPARQL execution as expected behaviour.

What happens if there is an empty service executor registry is less important. Your suggestion makes sense to me because it is a configuration error by the application.

[Aklakan]

I added a fix within #1388 - will test tomorrow.

[afs]

If you add "This fixes #1399" to the description, magic happens and this issue is automatically closed.