Re: [dotNetRDF-Support] How to validate RDF/XML with DotNetRdf

[Rob V. <rv...@do...>]

Good point

There may be a real bug which is that element names are resolved as
relative URIs rather than being resolved as QNames, I will look into this
further and report back

Your comments about remarks on the methods and warnings are good ones, I
will make a note to do as you suggest

Rob

On 9/24/12 12:44 PM, "Uldis Bojars" <cap...@gm...> wrote:

>Hi Rob,
>
>Thanks for looking into this.
>
>> The RDF/XML specification has the following to say on relative URI
>> resolution:
>
>It might be more of a problem with what is allowed in the RDF Property
>element name than with relative URIs (which, indeed, are fine as the
>program is allowed to determine the base URI itself).
>
>At least a modified example with xml:base added still produces same
>W3C RDF validator warnings:
>
><rdf:RDF xmlns:dc="http://purl.org/dc/elements/1.1"
>xml:base="http://captsolo.net/"
> xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
>   <rdf:Description rdf:about="http://localhost:8081/data/obj/1000">
>     <error>no info how to convert this element: creator</error>
>   </rdf:Description>
> </rdf:RDF>
>
>Error: {W104} Unqualified property elements are not allowed. Treated
>as a relative URI.[Line = 4, Column = 13]
>Error: {W136} Relative URIs are not permitted in RDF <error>[Line = 4,
>Column = 13]
>
>> When invoking the parser directly it does not assign a Base URI to the
>> Graph hence URI resolution fails and you get a parsing error.
>
>As noted above it might be something else (at least for W3C validator)
>but as long as DotNetRDF is able to notify about issues like this (it
>is, provided the parser method is used) I have nothing to complain
>about. :)
>
>> So this behavior is a little inconsistent and confusing but it is
>>somewhat
>> by design, the LoadFromFile() and FileLoader.Load() methods are designed
>> to be user friendly abstractions which remove some of the complexity of
>> selecting a parser and invoking it while also protecting users from some
>> common errors e.g. missing Base URI by setting up the parser invocation
>> appropriately.
>
>Would it make sense to document this difference in behavior? (E.g.,
>add a notice / warning to user-friendly methods saying the warnings
>will be hidden)
>
>It would help in cases like mine when looking for a parser that would
>warn of malformed RDF and other errors (to use as an RDF validator).
>In this case a user-friendly parser is not helpful at all and it is
>good to know one has to look at the parser method instead.
>
>> We could change the behavior to make it consistent (invoking a parser
>> directly on a file would set the Base URI for the Graph) but then we are
>> hiding errors from advanced users.
>
>Hiding errors from advanced users does not sound good :)
>
>Also, setting the Base URI might not get rid of the warning (maybe it
>does, I did not try the modified version on DotNetRDF yet).
>
>> With regards to warnings I don't have an example but it uses the
>>standard
>> .Net event pattern, Warning is an event defined by all IRdfReader
>> implementations and you add an event handler to it like any other .Net
>> event
>>
>> parser.Warning += new RdfReaderWarning(handlerMethod);
>
>I'll have to explore it. I have a reasonably good knowledge of RDF but
>a very limited knowledge of .Net or C#.
>
>Thanks,
>Uldis