Re: How are default profiles normatively established?

On Aug 23, 2010, at 14:08 , Richard Cyganiak wrote:

> I can't quite tell what the model for default profiles is.
> 
> Is it essentially a normative external profile document that is in effect for the entire document tree?
> 

That is my understanding...

> Or is it essentially a set of mappings that are normatively defined in the host language's specification document, and SHOULD also be available in an informative profile document, purely for consistency?
> 

*Conceptually* the answer is (in my view) the previous, ie, default term settings for a host language does not require any new/different mechanism from what we already have. In practice, of course, implementations may hardwire the default profile content in their parsing because there is also a note somewhere in the text that default profile specifications are not supposed to change, ie, processors are advised to cache them somehow. (Sorry not to refer to a particular place, I have a very bad connection today due to some networking change at my home.)

Whether a host language specification documents the content of the default profile becomes an editorial issue.

> Sections 7.5 makes it sound like the former, 7.2 makes it sound like the latter.
> 
> This matters for a few corner cases:
> 
> - What happens if the default profile document is unavailable due to server outage?
> 

If the caching mechanism works the processor should be able to go on happily...

> - Is the default profile in effect while processing *another profile document*?
> 

I think the answer is a clear no. Any effect of profiling is local to the document that refers to it; any profile document is an RDF(a) document on its own right, completely independent of the caller. Ie, I may process an SVG document with RDFa, using a default SVG profile for the SVG part, but referring to an external profile document in XHTML+RDFa. Clearly, the SVG default profile should have no effect on the XHTML+RDFa one.

I would think that is already clear from the document *if* the default profile is just a profile, ie, does not rely on any extra mechanism.

> I submit that the confusion has two sources:
> 
> 1. The terms “RDFa Profile” and “RDFa Profile Document” are used interchangeably, making it unclear what a “Default RDFa Profile” is. (My intuition is that a profile is an abstract data structure, while a profile document is a way of establishing a profile.)
> 
> 2. The section that explains RDFa Profile Documents does not explain how these documents relate to default profiles. (I think it should state that host languages SHOULD provide a profile document for their default profile, but that the profile document is never used in parsing.)
> 

Something like that is probably necessary, you're right.

Ivan


> Best,
> Richard


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