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In my graph I have the following assertions

  @prefix :     <http://www.example.org/~joe/contact.rdf#> .
  @prefix foaf: <http://xmlns.com/foaf/0.1/> .
  @prefix rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .

  :joesmith a foaf:Person ;
        foaf:givenname "Joe" ;
        foaf:family_name "Smith" ;
        foaf:homepage <http://www.example.org/~joe/> ;
        foaf:mbox <mailto:joe.smith@example.org> .

I loaded the graph in GraphDB.

If I point the GraphDB's Visual Graph to :joesmith, I would like to see all the triples but I see this graph

enter image description here

foaf:givenname and foaf:family_name are not shown in the graph but they are in node details tab, and it's ok.

Instead the node http://www.example.org/~joe/ is not connected to :joesmith. It seems pretty wired, since there is an explicit assertion belonging to :joesmith

Is this a bug or a problem in my data?

floatingpurr
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3 Answers3

2

This is definitely a bug. This bug affects Visual Graph functionality only. In the SPARQL results view, everything is fine.

The problem seems to be complex. There are two factors:

  • This namespace — <http://xmlns.com/foaf/0.1/> — is hardcoded somewhere.

  • This namespace is not proceeded correctly.

Let us consider the following examples.
Before each example, clear your repository and delete prefixes created in Setup > Namespaces.

Case 1

@prefix :     <http://www.example.org/~joe/contact.rdf#> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
@prefix rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .

  :joesmith a foaf:Person ;
        foaf:givenname "Joe" ;
        foaf:family_name "Smith" ;
        foaf:homepage <http://www.example.org/~joe/> ;
        foaf:mbox <mailto:joe.smith@example.org> .

As you have pointed out, <http://www.example.org/~joe/> is not shown.

Case 2

@prefix :     <http://www.example.org/~joe/contact.rdf#> .
@prefix foo: <http://xmlns.com/foaf/0.1/> .
@prefix rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .

  :joesmith a foo:Person ;
        foo:givenname "Joe" ;
        foo:family_name "Smith" ;
        foo:homepage <http://www.example.org/~joe/> ;
        foo:mbox <mailto:joe.smith@example.org> .

In this case, <http://www.example.org/~joe/> is not shown.

Case 3

@prefix :     <http://www.example.org/~joe/contact.rdf#> .
@prefix foaf: <http://xmlns.com/foaf/01/> .
@prefix rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .

  :joesmith a foaf:Person ;
        foaf:givenname "Joe" ;
        foaf:family_name "Smith" ;
        foaf:homepage <http://www.example.org/~joe/> ;
        foaf:mbox <mailto:joe.smith@example.org> .

In this case, <http://www.example.org/~joe/> is shown.

Case 4

@prefix :     <http://www.example.org/~joe/contact.rdf#> .
@prefix foaf: <http://xmln.com/foaf/0.1/> .
@prefix rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .

  :joesmith a foaf:Person ;
        foaf:givenname "Joe" ;
        foaf:family_name "Smith" ;
        foaf:homepage <http://www.example.org/~joe/> ;
        foaf:mbox <mailto:joe.smith@example.org> .

In this case, <http://www.example.org/~joe/> is shown.

I'll try to contact their support team directly by sending email.

UPDATE 1

They say there are four kinds of RDF terms:

  1. URIs
  2. Literals
  3. Blank nodes
  4. URIs considered by their team as "not real".

From GraphDB query logs, one can ascertain what URIs are of the fourth kind.

BIND (strstarts(str(?p), "http://purl.org/dc/terms/") ||
      strstarts(str(?p), "http://dbpedia.org/ontology/subsidiary") AS ?isMeta)
    FILTER(!strstarts(str(?p), "http://www.w3.org/2002/07/owl#")
              && !strstarts(str(?p), "http://www.w3.org/1999/02/22-rdf-syntax-ns#")
              && !strstarts(str(?p), "http://www.w3.org/2000/01/rdf-schema#")
              && !strstarts(str(?p), "http://www.openrdf.org/schema/sesame#")
              && !strstarts(str(?p), "http://www.ontologydesignpatterns.org/ont/dul/DUL.owl")
              && !strstarts(str(?p), "http://www.w3.org/ns/prov")
              && !strstarts(str(?p), "http://dbpedia.org/ontology/wikiPage")
              && !strstarts(str(?p), "http://dbpedia.org/property/wikiPage")
              && !strstarts(str(?p), "http://www.omg.org/spec/")
              && !strstarts(str(?p), "http://www.wikidata.org/entity/")
              && !strstarts(str(?p), "http://factforge.net/")
              && ?p != <http://dbpedia.org/property/logo>;
              && ?p != <http://dbpedia.org/property/hasPhotoCollection>;
              && ?p != <http://dbpedia.org/property/website>;
              && ?p != <http://dbpedia.org/property/homepage>;
              && ?p != <http://dbpedia.org/ontology/thumbnail>;
              && ?p != <http://xmlns.com/foaf/0.1/depiction>;
              && ?p != <http://xmlns.com/foaf/0.1/homepage>;
            )

UPDATE 2

In GraphDB 8.3, it was fixed in some way:

GDB-2076 - Visual graph: consistent handling of foaf/dbpedia predicates that point to IRIs but are treated as literals

Stanislav Kralin
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2

The Visual graph functionality shows resources (= things that have IRIs) and how they are connected. Since foaf:givenname and foaf:family_name point to literals they aren't shown in the graph. You are right that foaf is handled specially. The properties foaf:homepage and foaf:depiction are treated as if they point to literals (and hence are not shown) because they are used to refer to URLs on the internet and not as real RDF IRIs pointing to other resources in the graph. No other foaf properties are treated specially.

In a future version of GraphDB you'll have a more fine grained control over what's omitted.

Edited: not showing foaf:homepage in the side panel (where literals are shown) is inconsistent with hiding it from the graph. This will be addressed in the next version.

Pavel Mihaylov
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  • Another thing: if we are to be consistent we should do the same with foaf:mbox as it points to an email address and not an RDF resource. – Pavel Mihaylov Jul 14 '17 at 12:50
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    According to this logic, shouldn't you consider as an literal any dereferenceble URI? Anyway, if `foafname:homepage` value is "in fact" a literal, why it is not displayed in the right sidepanel? – Stanislav Kralin Jul 14 '17 at 13:04
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    @PavelMihaylov, as Stanislav mentioned, in the side panel we can see only `foaf:givenname` and `foaf:family_name` as predicates ranging to a literal but `foaf:mbox` is not displayed there. If I search for `http://www.example.org/~joe/` in the VisualGraph, it appears as a disconnected node... – floatingpurr Jul 14 '17 at 13:28
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    Unfortunately there is no way to tell if a given IRI (something stored as an IRI and not a literal) was meant to refer to an RDF resource or be used as a URL. In the case of foaf:homepage we have used some human reasoning with the idea to have clearer graphs. Not displaying it in the side panel is definitely a bug and will be addressed in the next release. – Pavel Mihaylov Jul 14 '17 at 14:44
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Since GraphDB 8.3 you configure all of the queries of the Visual Graph by creating your own Visual Graph Config. Check the documentation here. http://graphdb.ontotext.com/documentation/enterprise/devhub/custom-graph-views.html?highlight=visual%20graph%20config

There is also a webinar. https://www.ontotext.com/custom-graph-views-webinar-recording/

Desislava Hristova
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    Please just note if you want to promote or recommend your own product/blog, there are some [guidelines in place](/help/promotion) for doing so. Following them will help you avoid giving the impression that you're spamming. Could you please edit to explicitly state your affiliation? (If you're not actually affiliated, it may be worth mentioning that as well.) – Filnor Dec 17 '18 at 10:36