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Re: Important Question re. WebID Verifiers & Linked Data

From: Mo McRoberts <mo.mcroberts@bbc.co.uk>
Date: Thu, 22 Dec 2011 16:05:43 +0000
Cc: public-xg-webid@w3.org
Message-Id: <E508BE3F-0836-4618-9838-31EE53308453@bbc.co.uk>
To: Kingsley Idehen <kidehen@openlinksw.com>

On 22 Dec 2011, at 15:42, Kingsley Idehen wrote:

> On 12/22/11 9:57 AM, Patrick Logan wrote:
>> OK, that seems manageable, assuming it all specs out.
>> 
>> So looking at the 12 December 2012 draft (
>> http://www.w3.org/2005/Incubator/webid/spec/#in-portable-contacts-format-using-grddl
>> ), it looks like (2) RDFa and (4) RDF/XML are in the draft, but (1)
>> HTML+Microdata and (3) Turtle are not.
>> 
>> In particular the two most relevant sections look to be:
>> 
>> ========
>> 3.2.4.1 Processing the WebID Profile
>> 
>> The Verification Agent must be able to process documents in RDF/XML
>> [RDF-SYNTAX-GRAMMAR] and RDFa in XHTML [XHTML-RDFA]. The result of
>> this processing should be a graph of RDF relations that is queryable,
>> as explained in the next section.
>> ========
>> 
>> How should that read instead?
> 
> ========
> 3.2.4.1 Processing the WebID Profile
> 
> The Verification Agent SHOULD be able to process at least one of the following structured documents types: RDF/XML
> [RDF-SYNTAX-GRAMMAR], RDFa in XHTML [XHTML-RDFA] or HTML, Turtle, and Microdata in HTML. The result of
> this processing should be a graph of RDF relations that is queryable,
> as explained in the next section.
> ========


It needs to be tighter than that. If there is to be support for multiple formats (and IMO there should be), the flexibility needs to happen on the publisher side, not the consumer side — otherwise you end up with the situation where people publish things perfectly conformantly and they can't be processed by consumers which are equally conformant. WebID is useless if it only works some of the time.

Assuming Microdata is baked in:—

========
3.2.4.1 Processing the WebID Profile

The Verification Agent MUST be able to process the following structured document types:

* RDF/XML [RDF-SYNTAX-GRAMMAR]
* RDFa in XHTML [XHTML-RDFA]
* Microdata in HTML [HTML5]

A Verification Agent MAY also support the processing of other structured document types.
========

========
2.2 Publishing the WebID Profile Document

The protocol does not depend on any particular serialisation of the graph, provided that agents are able to parse that serialisation and obtain the graph automatically. Technologies such as GRDDL [GRDDL-PRIMER] for example permit any XML format to be transformed automatically to a graph of relations. Yet for reasons of interoperability is has been decided that the document must be published at least in one of RDFa [XHTML-RDFA], RDF/XML [RDF-SYNTAX-GRAMMAR], or Microdata in HTML [HTML5]. HTTP Content Negotiation [SWBP-VOCAB-PUB] can be employed to aid in publication and discovery of multiple distinct serialisations of the same graph at the same URL. A WebID Profile Document MAY also be published in other formats, provided it can be retrieved by resolving the WebID URI.
========

Similarly, there needs to be working somewhere which makes HTTP and HTTPS a MUST with other schemes a MAY, but reading the spec I couldn't figure out entirely where to insert it -- I think the first couple of paras of §2.1 may need rewording to make clear the relationship between the SAN URI and the document.

There should also be a note, somewhere near the top, to the effect that future versions of the specification will very likely revise which types of structured document and which protocols are a MUST and which aren’t. This is 1.0. You should be able to know that a WebID 1.0 VA can handle RDF/XML, RDFa and Microdata for definite, and — for example — that if you want to only bothering to publish Turtle, your WebID will only work with WebID 1.1 VAs (for example).

M.

-- 
Mo McRoberts - Technical Lead - The Space,
0141 422 6036 (Internal: 01-26036) - PGP key CEBCF03E,
Project Office: Room 7083, BBC Television Centre, London W12 7RJ



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Received on Thursday, 22 December 2011 16:06:28 GMT

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