SHACL Problem : Shape with multiple types: <http://www.w3.org/ns/shacl#PropertyShape>, <http://www.w3.org/ns/shacl#NodeShape> #4287

volkerjaenisch · 2022-11-19T20:05:18Z

volkerjaenisch
Nov 19, 2022

Dear RDF4J Users!

Currently we am implementing SHACL for an OpenData portal (http://datenadler.de).
We are Python programmers so we planed to go with pySHACL. But our Plan B is RDF4J which we are currently using as our backend.

Testing our Plan B we stumbled over the following exception of RDF4J reading a SHAPE file.

javax.servlet.ServletException: org.eclipse.rdf4j.repository.RepositoryException: Shape with multiple types: <http://www.w3.org/ns/shacl#PropertyShape>, <http://www.w3.org/ns/shacl#NodeShape>
	org.eclipse.rdf4j.workbench.proxy.WorkbenchServlet.handleRequest(WorkbenchServlet.java:160)
	org.eclipse.rdf4j.workbench.proxy.WorkbenchServlet.service(WorkbenchServlet.java:112)
	org.eclipse.rdf4j.workbench.proxy.WorkbenchGateway.service(WorkbenchGateway.java:117)
	org.eclipse.rdf4j.workbench.base.AbstractServlet.service(AbstractServlet.java:129)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	org.eclipse.rdf4j.workbench.proxy.CacheFilter.doFilter(CacheFilter.java:64)
	org.eclipse.rdf4j.workbench.proxy.CookieCacheControlFilter.doFilter(CookieCacheControlFilter.java:56)

Root Cause

org.eclipse.rdf4j.repository.RepositoryException: Shape with multiple types: <http://www.w3.org/ns/shacl#PropertyShape>, <http://www.w3.org/ns/shacl#NodeShape>
	org.eclipse.rdf4j.http.client.SPARQLProtocolSession.execute(SPARQLProtocolSession.java:1095)
	org.eclipse.rdf4j.http.client.SPARQLProtocolSession.executeNoContent(SPARQLProtocolSession.java:1049)
	org.eclipse.rdf4j.http.client.RDF4JProtocolSession.upload(RDF4JProtocolSession.java:1103)
	org.eclipse.rdf4j.http.client.RDF4JProtocolSession.upload(RDF4JProtocolSession.java:928)
	org.eclipse.rdf4j.http.client.RDF4JProtocolSession.upload(RDF4JProtocolSession.java:919)
	org.eclipse.rdf4j.repository.http.HTTPRepositoryConnection.add(HTTPRepositoryConnection.java:447)
	org.eclipse.rdf4j.workbench.commands.AddServlet.add(AddServlet.java:94)
	org.eclipse.rdf4j.workbench.commands.AddServlet.doPost(AddServlet.java:53)
	org.eclipse.rdf4j.workbench.base.TransformationServlet.service(TransformationServlet.java:98)
	org.eclipse.rdf4j.workbench.base.AbstractServlet.service(AbstractServlet.java:129)
	org.eclipse.rdf4j.workbench.proxy.ProxyRepositoryServlet.service(ProxyRepositoryServlet.java:100)
	org.eclipse.rdf4j.workbench.proxy.WorkbenchServlet.service(WorkbenchServlet.java:215)
	org.eclipse.rdf4j.workbench.proxy.WorkbenchServlet.handleRequest(WorkbenchServlet.java:137)
	org.eclipse.rdf4j.workbench.proxy.WorkbenchServlet.service(WorkbenchServlet.java:112)
	org.eclipse.rdf4j.workbench.proxy.WorkbenchGateway.service(WorkbenchGateway.java:117)
	org.eclipse.rdf4j.workbench.base.AbstractServlet.service(AbstractServlet.java:129)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	org.eclipse.rdf4j.workbench.proxy.CacheFilter.doFilter(CacheFilter.java:64)
	org.eclipse.rdf4j.workbench.proxy.CookieCacheControlFilter.doFilter(CookieCacheControlFilter.java:56)

Can someone please explain what is going wrong.

The shape file comes from the EU
https://github.com/SEMICeu/DCAT-AP/blob/master/releases/2.1.1/dcat-ap_2.1.1_shacl_shapes.ttl

pySHACL reads and uses this file with no complains. I also checked graphDB (to make sure my RDF4J is installed correctly) with the exact same outcome.

Any help appreciated

Cheers,
Volker

barthanssens · 2022-11-19T21:15:28Z

barthanssens
Nov 19, 2022
Collaborator

Hi Volker,

could you tell us which RDF4J version you're using ?
Thanks

Bart

0 replies

volkerjaenisch · 2022-11-19T21:32:12Z

volkerjaenisch
Nov 19, 2022
Author

Dear Bart! Am 19.11.22 um 22:15 schrieb Bart Hanssens:

Hi Volker, could you tell us which RDF4J version you're using ? Thanks

I am using the code from yesterday :-) Application Information Application Name RDF4J Workbench Version 4.2.1 Cheers, Volker

…

-- ========================================================= inqbus Scientific Computing Dr. Volker Jaenisch Hungerbichlweg 3 +49 (8860) 9222 7 92 86977 Burggenhttps://inqbus.de =========================================================

0 replies

volkerjaenisch · 2022-11-19T21:33:30Z

volkerjaenisch
Nov 19, 2022
Author

Dear Bart! Application Information Application name: RDF4J Server Version: 4.2.1 Data directory: /var/lib/tomcat/.RDF4J/server Runtime Information Operating System: Linux 5.10.0-19-amd64 (amd64) Java Runtime: Debian OpenJDK 64-Bit Server VM 11.0.16 Process User: tomcat Memory Percentage in use: 4 % Used: 320 MB Maximum: 7.994 MB

…

-- ========================================================= inqbus Scientific Computing Dr. Volker Jaenisch Hungerbichlweg 3 +49 (8860) 9222 7 92 86977 Burggenhttps://inqbus.de =========================================================

0 replies

barthanssens · 2022-11-21T11:36:15Z

barthanssens
Nov 21, 2022
Collaborator

Thanks, I'll look into it in the afternoon

1 reply

volkerjaenisch Nov 21, 2022
Author

@barthanssens
Thank you so much!

barthanssens · 2022-11-21T12:29:11Z

barthanssens
Nov 21, 2022
Collaborator

Looks like RDF4J has an issue with sh:name: if I copy the DCAT-AP file and remove the sh:name property from all the shapes, the SHACL file is loaded without error

0 replies

barthanssens · 2022-11-21T12:41:58Z

barthanssens
Nov 21, 2022
Collaborator

Arguably this is not a bug, since, according to the SHACL ontology (https://github.com/w3c/data-shapes/blob/gh-pages/shacl/shacl.ttl), sh:name is (only) a property of a sh:PropertyShape

While the DCAT-AP shacl file uses it on sh:NodeShape, effectively turning it into a sh:PropertyShape as well (hence the exception being thrown)

3 replies

volkerjaenisch Nov 21, 2022
Author

Ah!
Thank you for the explanation. I understand the cause of the exception, now.
But how to proceed from here?

I may open a bugreport at DCAT-AP and address the ontology domain problem:

sh:name
	a rdf:Property ;
	rdfs:label "name"@en ;
	rdfs:comment "Human-readable labels for the property in the context of the surrounding shape."@en ;
	rdfs:domain sh:PropertyShape ;
	# range: xsd:string or rdf:langString
	rdfs:isDefinedBy sh: .

But I guess that the answer will be: "A SHACL entity given a sh:name then has an additional type, so what? Problem of your engine" :-).

And this argumentation is not completely nonsense. Is it justified to throw an exception in this case? Does having two types breaks SHACL. Since two other SHACL processors correctly using this shape file, I would think that this is not the case.

Also the DCAT-AP SHACL shape runs without flaw through the SHACL shape validator: https://www.itb.ec.europa.eu/shacl/shacl/upload.

Maybe this exception is really not necessary.

Cheers,
Volker

barthanssens Nov 21, 2022
Collaborator

Hi @volkerjaenisch

I've opened an issue SEMICeu/DCAT-AP#245 (so at least people are aware that it might be an issue in at least 1 engine)

While technically RDF4J is correct (IMHO), I do understand that it makes sense that this property is also present on NodeShapes
(this should be fixed by the W3C SHACL working group)

So we can look into a fix/work-around in RDF4J, just trying to find out what caused the issue.

Best regards

Bart

volkerjaenisch Nov 21, 2022
Author

👍

barthanssens · 2022-11-21T12:59:34Z

barthanssens
Nov 21, 2022
Collaborator

A workaround could be e.g. something along the lines of :

Model rules = Rio.parse(new FileReader("dcat-ap-221.ttl"), RDFFormat.TURTLE, (Resource) null);
rules.remove(null, SHACL.NAME, null);

connection.begin();
connection.add(rules, RDF4J.SHACL_SHAPE_GRAPH);
connection.commit();

2 replies

volkerjaenisch Nov 21, 2022
Author

Yes, that will surely workaround the exception, but on the other Hand the sh:name attributes are quite important for the human readability of the result report.

barthanssens Nov 21, 2022
Collaborator

Agree :-) But as mentioned, actually the SHACL specification itself should be updated to also allow sh:name on sh:NodeShape (instead of only on sh:PropertyShape) ...

The DCAT-AP shacl file somewhat incorrectly uses it on a sh:NodeShape

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SHACL Problem : Shape with multiple types: <http://www.w3.org/ns/shacl#PropertyShape>, <http://www.w3.org/ns/shacl#NodeShape> #4287

volkerjaenisch Nov 19, 2022

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