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Re: conformance checker for HTML+ARIA?

From: Felix Sasaki <fsasaki@w3.org>
Date: Wed, 01 Oct 2008 08:57:43 +0900
Message-ID: <48E2BCF7.7020900@w3.org>
To: Henri Sivonen <hsivonen@iki.fi>
CC: W3C WAI-XTECH <wai-xtech@w3.org>, www-validator Community <www-validator@w3.org>, HTML WG <public-html@w3.org>

Henri Sivonen さんは書きました:
>
> On Sep 30, 2008, at 11:24, Steven Faulkner wrote:
>
>> Members of the development community are asking for a way to check
>> their HTML+ ARIA documents for conformance and one that does can be
>> used to check all flavours of (x)HTML without all ARIA associated code
>> being flagged as non conformant.
>
> Which is correct behavior, because ARIA markup is not valid according 
> to HTML 4.01 or XHTML 1.0. ARIA markup isn't valid according to the 
> current HTML5 draft, either, but HTML5 isn't done yet.
>
>> The experimental HTML5+ARIA checker developed by Henri Sivonen does 
>> this, but it is limited to the HTML5 doctype.
>
> I'm not convinced that the HTML5 doctype is a real problem in itself, 
> although I can see how it is problematic that HTML5 as currently 
> drafted doesn't make upgrading existing markup templates smooth by 
> obsoleting some popular attributes (such as the border attribute on 
> <img> and align attribute on <td>).
>
>> It also flags issues based on a set of rules, defined by Henri, on 
>> what constitutes conformant HTML5+ARIA (for example role="document" 
>> is not allowed) [2].
>
> I made up rules myself, because neither the ARIA spec nor the HTML5 
> spec was addressing ARIA in HTML integration in a satisfactory way. 
> The rules I made up were meant as an executable proposal to move this 
> issue forward. I got some feedback from individual PFWG participants, 
> but I didn't get feedback that could be considered as indication of 
> what PFWG intends to do about document conformance in the context of a 
> concrete host language.
>
> (Aside: After I made the executable proposal about HTML5+ARIA, I have 
> answered to inquiries about SVG+ARIA saying that it doesn't make sense 
> for me to give SVG+ARIA the same treatment of me making stuff up 
> before getting some sort of indication whether the PFWG agrees that 
> the general approach I proposed makes sense.)
>
>> Can we build ARIA checking into the W3C validator so that ARIA 
>> conformance can be checked seemlessly with HTML whatever the version?
>
> HTML 2.0, HTML 3.2 and HTML 4.01 are what they are, and they don't 
> allow ARIA markup--just like they don't allow <video>.
>
> Can we solve the practical problem here without backporting newer 
> markup features piecemeal and pretending (via "errata" or otherwise) 
> that old HTML specs allowed something they didn't allow? Surely the 
> label "HTML5" vs. "HTML 4" in the validator UI isn't the practical 
> problem?
>
> On Sep 30, 2008, at 12:26, David Dorward wrote:
>
>> The HTML Working Group is chartered to "maintain and produce incremental
>> revisions to the HTML specification"[1], which I would imagine HTML 4.01
>> + ARIA would fall under. I imagine you would raise the matter with them
>> and see if they would be willing to work with the WAI to publish a small
>> Recommendation which makes reference to ARIA and HTML 4.01, defines a
>> Doctype and includes a DTD.
>
> HTML 4.01 is so broken in so many ways that I think it doesn't make 
> sense to divert resources to put out individual fires.
>
> A bit over a year ago, I was advised against putting effort into 
> maintaining the HTML 4.01 and XHTML 1.0 functionality of Validator.nu. 
> I didn't take the advice back then, which is regrettable, because now 
> people ask me to put more and more effort into that dead end instead 
> of the users just using the HTML5.
>
> That is, it seems that people recognize that Validator.nu offers 
> better technology (datatype checking, etc.) compared to DTD-based 
> validation but, yet, shy away from HTML5 validation and instead want 
> the same improvements in schemas that are labeled HTML 4.01 or XHTML 1.0.
>
> Instead of changing the HTML 4.01 and XHTML 1.0 schemas to be even 
> further away from what those specs (vaguely) said while keeping them 
> labeled HTML 4.01 and XHTML 1.0 for marketing reasons, I would prefer 
> to find out what makes the HTML5 definition of validity impractical 
> for authors, remove those blockers and then talk about HTML5 
> validation instead of pretending that HTML 4 validation changed to 
> include new stuff.
>
> If we make one-off HTML 4 + Foo validation targets, but where do we 
> stop? Should we also have an HTML 4 + <canvas> validation target and 
> an HTML 4 + <video> validation target?
>
> On Sep 30, 2008, at 11:44, David Dorward wrote:
>
>> Steven Faulkner wrote:
>>> Can we build ARIA checking into the W3C validator so that ARIA
>>> conformance can be checked seemlessly with HTML whatever the version?
>>>
>> That wouldn't really make sense. It would be more logical to create an
>> HTML 4 + ARIA DTD and validate against that.
>
> Such a DTD could have holes that ARIA could drive through with error 
> messages removed, but DTDs are inadequate for actually validating 
> ARIA--i.e. detecting ARIA errors.
>
>>> People seem to want a form of checking provided by the W3C that will
>>> tell them (for example) that their HTML code is valid and their ARIA
>>> code is valid.
>>>
>> If it has ARIA in it, then their HTML (by any current W3C recommendation
>> that I know of) isn't valid.
>
> Right.
>
>> You can't fix this problem at the tool level, you need to address it 
>> at the standards level.
>
> Exactly. Asking people to produce the tools when the relevant working 
> groups don't work jointly on an actual normative conformance 
> definition doesn't really make sense. Or it makes sense on the 
> prototyping level but then what you get is the validator developer 
> making stuff up.
>
> On Sep 30, 2008, at 12:25, Gez Lemon wrote:
>
>> It doesn't resolve the whole issue of ensuring that ARIA is used
>> correctly with a native markup language, but if the ARIA specification
>> is available in a machine readable format (such as what attribute
>> values are valid for a particular attribute, and what attributes can
>> be used with particular roles in RDF), we could build a basic
>> validator to ensure at least the ARIA part is used according to its
>> specification.
>
> In my experience, the RDF definition was not useful when implementing 
> the HTML5+ARIA prototype. I looked at the English prose and the tables 
> instead.
>
> On Sep 30, 2008, at 12:38, Jason White wrote:
>
>> Yes, but unless the validator includes a Javascript interpreter and a 
>> DOM
>> implementation, all that can be checked are the Aria attributes of the
>> document prior to the execution of scripts that modify it.
>>
>> Anything involving live regions or Javascript functions that change 
>> states or
>> properties would largely escape any lesser validator. Maybe the 
>> validator
>> needs to be written as a user agent extension that can verify 
>> correctness as
>> changes are made.
>
> The validator doesn't need to run in the same process as the browser. 
> It would be sufficient for a browser to serialize a snapshot of the 
> DOM and send it over to another process for validation (e.g. over 
> HTTP). Currently, one can approximate this with bookmarklets and 
> Validator.nu. However, there is a problem that currently Validator.nu 
> supports input in the text/html and XML serializations, but neither of 
> those can express all the possible DOM trees, so to make things work 
> for all possible DOMs, a new format and a SAX parser (in Java) for it 
> on the Validator.nu side and a serializer in JavaScript for the 
> browser side would be needed.
>
> I have gotten inquiries about putting Validator.nu inside the browser 
> process. I think that embedding a JVM in the browser process would be 
> unnecessarily heavyweight. If someone wishes to pursue the in-process 
> path with Validator.nu, I suggest using the compiler from Google Web 
> Toolkit as a means of taking Java code and loading it onto the 
> JavaScript VM of the target browser.
>
> On Sep 30, 2008, at 14:10, Michael(tm) Smith wrote:
>
>> I would think it'd be doable to add support in validator.nu
>> experimental support for validating XHTML 1.0 and HTML 4.01
>> documents containing ARIA markup.
>
> It's possible to backport the ARIA stuff to the legacy schemas, but 
> wouldn't it make more sense to forward port this stuff from HTML4 that 
> keeps people from upgrading to HTML5 as their validation target?
>
>> But I think it might be worthwhile to have a discussion with Henri 
>> about whether those rules can or should be adjusted.
>
> They can be adjusted. I was trying to poke the relevant working groups 
> into saying how by showing an executable proposal.
>
>> And/or we should discuss the idea of actually
>> defining a spec for HTML 4.01 + ARIA, without reference to DTDs or
>> perhaps without reference to any normative formal schema language
>> at all.
>
> I think we should instead put that effort into producing proper spec 
> text defining conformance criteria for HTML5 + ARIA.
>
> On Sep 30, 2008, at 14:22, David Dorward wrote:
>
>> Michael(tm) Smith wrote:
>>> That said, there's nothing blocking anybody interested in pursuing
>>> the idea of producing a DTD for HTML 4.01 + ARIA and negotiating
>>> with the validator.w3.org maintainers to add support for it.
>> A DTD is a DTD. The validator works with DTDs, explicit support doesn't
>> need to be added. (Although, if its popular, it might be worth adding it
>> to the local catalogue (for speed) and the list of possible Doctype
>> overrides).
>
> Aside: Validator.nu allows user-provided RELAX NG and Schematron 
> schemata.

And this functionality, btw., is used within at least one W3C working 
group for a specialized, multilingual, XHTML-based document format. See
http://www.w3.org/2007/02/japanese-layout/docs/aligned/#documentgeneration
http://www.w3.org/2007/02/japanese-layout/docs/aligned/check

Felix


>
> On Sep 30, 2008, at 15:07, Aaron M Leventhal wrote:
>
>> We do need a solution soon. This keeps coming up.
>>
>> I think W3C should drive this, since developers want the official W3C 
>> stamp of approval.
>
> Perhaps past emphasis on a W3C stamp of approval is part of the 
> problem.His
>
>> W3C can use a multi-pronged solution:
>> 1. Short term: create new DTD and ask W3C to host it. It can be 
>> considered "beta" for now. It needs to include HTML 4 + tabindex 
>> changes (allow negative numbers and on any element) + WAI-ARIA.
>> 2. Medium term: DTD's are of limited value, and W3C can utilize 
>> something that provides more in-depth checking. Perhaps Validator.nu, 
>> but certainly at least looking at Henri's approach
>
> The W3C is already hosting an instance of the Validator.nu software as 
> a back end to a development version of the W3C Validator.
>
> If you use the HTML5 doctype, you can get the same ARIA validation at 
> http://qa-dev.w3.org/wmvs/HEAD/ that you can get at 
> http://html5.validator.nu/.
>
> Why promote a less expressive DTD approach?
>
>> Getting around validation by inserting content via script is 
>> happening. I'm seeing developers recommend that ARIA is inserted 
>> dynamically onload, just for that reason. Seems not to be useful.
>
> Agreed.
>
> On Sep 30, 2008, at 15:39, Michael(tm) Smith wrote:
>
>> I'd suspect that the
>> difficult part is getting agreement about what exactly the
>> specific validity constraints in the DTD should be. I mean, I get
>> the impression from the message that Steven cited that there's not
>> agreement on the schema that Henri made.
>
> Right. The problem of the spec missing can't be fixed by switching to 
> legacy validation technology. :-)
>
>>
>
> Furthermore, trying to get the W3C Validator to add a new DTD would 
> presumably involve putting a non-standard doctype on the documents to 
> be validated. If authors were willing to do that, why wouldn't they be 
> willing to use the doctype <!DOCTYPE html> if the validity definition 
> of HTML5 were tweaked along the lines I suggested in
> http://lists.w3.org/Archives/Public/public-html/2008Aug/0958.html
>
> On Sep 30, 2008, at 16:11, Michael(tm) Smith wrote:
>
>> I think having a normative spec for ARIA is HTML 5 is absolutely 
>> something that the HTML WG needs to produce.
>
> Hopefully together with the PFWG.
>
>> But having a spec of HTML 4.01 + ARIA is not.
>
> Agreed.
>
Received on Tuesday, 30 September 2008 23:58:22 GMT

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