Registering .owl as RDF/XML

[Andy Seaborne]

I wrote a test program (at end) to investigate the difference when .owl 
is registered as RDF/XML format and it is not.

The difference turns the case where the system has no idea of the 
language into trying RDF/XML.

When the app provides a suggested language, this is used unless the far 
end gives a non-text/plain content type. "text/plain" is too unreliable 
to assume anything as it's what you get if you do nothing.  RIOT does 
not assume ISO-8859-1 in this case either.

In both cases, the server declared type is used.  This covers the case 
where the publisher changes the content type of a URL wihtou braking the 
application that used to work.

        Andy

== .owl not registered

URL=http://example/file.owl
Content-type=null
Lang=null
  ==> null

URL=http://example/file.owl
Content-type=null
Lang=Lang:Turtle
  ==> Lang:Turtle

URL=http://example/file.owl
Content-type=text/plain
Lang=null
  ==> null

URL=http://example/file.owl
Content-type=text/plain
Lang=Lang:Turtle
  ==> Lang:Turtle

URL=http://example/file.owl
Content-type=application/rdf+json
Lang=null
  ==> Lang:RDF/JSON

URL=http://example/file.owl
Content-type=application/rdf+json
Lang=Lang:Turtle
  ==> Lang:RDF/JSON



== With .owl registered

URL=http://example/file.owl
Content-type=null
Lang=null
  ==> Lang:RDF/XML

URL=http://example/file.owl
Content-type=null
Lang=Lang:Turtle
  ==> Lang:Turtle

URL=http://example/file.owl
Content-type=text/plain
Lang=null
  ==> Lang:RDF/XML

URL=http://example/file.owl
Content-type=text/plain
Lang=Lang:Turtle
  ==> Lang:Turtle

URL=http://example/file.owl
Content-type=application/rdf+json
Lang=null
  ==> Lang:RDF/JSON

URL=http://example/file.owl
Content-type=application/rdf+json
Lang=Lang:Turtle
  ==> Lang:RDF/JSON

public static void main(String ... argv) throws Exception
{
    test("http://example/file.owl";,
         null, null) ;
    test("http://example/file.owl";,
         null, Lang.TTL) ;

    test("http://example/file.owl";,
         WebContent.contentTypeTextPlain, null) ;
    test("http://example/file.owl";,
         WebContent.contentTypeTextPlain, Lang.TTL) ;

    test("http://example/file.owl";,
         WebContent.contentTypeRDFJSON, null) ;
    test("http://example/file.owl";,
         WebContent.contentTypeRDFJSON, Lang.TTL) ;
}

public static void test(String url, String ctStr, Lang lang) {
    System.out.printf(
        "URL=%s\nContent-type=%s\nLang=%s\n", url, ctStr, lang) ;
    Lang lang2 = RDFDataMgr.determineLang(url, ctStr, lang) ;
    System.out.println("  ==> "+lang2) ;
    System.out.println() ;
    }