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

[Uldis B. <cap...@gm...>]

This section looks related:

http://www.w3.org/TR/rdf-syntax-grammar/#section-Identifiers

Uldis

On Mon, Sep 24, 2012 at 10:55 PM, Rob Vesse <rv...@do...> wrote:
> 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
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