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Re: ISSUE-4: html-versioning / ISSUE-84: legacy-doctypes - Straw Poll for Objections

From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Date: Sat, 14 Aug 2010 05:03:24 +0200
To: Adam Barth <w3c@adambarth.com>
Cc: "Roy T. Fielding" <fielding@gbiv.com>, Robin Berjon <robin@berjon.com>, Maciej Stachowiak <mjs@apple.com>, HTML WG <public-html@w3.org>
Message-ID: <20100814050324568313.aa2652c2@xn--mlform-iua.no>
Adam Barth, Fri, 13 Aug 2010 19:23:52 -0700:
> Hi Roy,
> I looked on the results page for the ISSUE-4 questionnaire, and I
> didn't see your objections to my change proposal noted there.  It's
> unfortunate that you were not able to participate in the decision
> process up to now.  Rather than drag this issue through another
> centithread, perhaps the chairs would be willing to accept your
> response to the questionnaire even though the deadline has past?


> Adam


> On Fri, Aug 13, 2010 at 4:20 PM, Roy T. Fielding <fielding@gbiv.com> wrote:
>> On Aug 13, 2010, at 5:39 AM, Robin Berjon wrote:
>>> On Aug 12, 2010, at 19:41 , Roy T. Fielding wrote:
>>>> On Aug 12, 2010, at 5:55 AM, Robin Berjon wrote:
>>>>> On Jul 22, 2010, at 11:02 , Maciej Stachowiak wrote:
>>>>>> The poll is available here, and it will run through Friday, July 30th:
>>>>>> http://www.w3.org/2002/09/wbs/40318/issues-4-84-objection-poll/

>>>>>> Please read the introductory text before entering your response.
>>>>>> In particular, keep in mind that you don't *have* to reply. You 
>>>>>> only need to do so if you feel your objection to one of the 
>>>>>> options is truly strong, and has not been adequately addressed 
>>>>>> by a clearly marked objection contained within a Change Proposal 
>>>>>> or by someone else's objection. The Chairs will be looking at 
>>>>>> strength of objections, and will not be counting votes.
>>>>> I was on vacation while this poll was open, but I wanted to 
>>>>> register my strong objection to the addition of a versioning 
>>>>> indicator of any kind. It is an approach that with respect I can 
>>>>> only deem naïve and that adds complexity without addressing the 
>>>>> issue of compatible behaviour across change.
>>>>> I have covered the topic previously, going into some lengths to 
>>>>> describe architectural issues with version indicators as part of 
>>>>> a discussion with the TAG in 
>>>>> http://lists.w3.org/Archives/Public/www-tag/2009Dec/0116.html, as 
>>>>> well as in a lighterweight description that ends with a decision 
>>>>> tree about the cases in which you need a version indicator at 
>>>>> http://berjon.com/blog/2009/12/xmlbp-naive-versioning.html.

>>>> I find it incredible that such a large group of people can manage
>>>> to make identical "strong objections" based on an argument that
>>>> only holds true if browsers are the only consumers of HTML.
>>>> For all other consumers and producers, every objection made in
>>>> that poll is demonstrably false.  The problem is that none of
>>>> the other implementors of HTML bother to participate here because
>>>> their requirements are routinely ignored.
>>> My argument very definitely does not come from any manner of 
>>> browser-oriented point of view. My background here is entirely in 
>>> robust processing of evolving vocabularies (typically XML) in 
>>> situations that don't even remotely involve a browser. I have seen 
>>> no convincing argument that what applies to the processing of XML 
>>> would not apply equally to HTML, whether in a browser context or 
>>> not.
>> Your argument does not apply to the processing of XML in general.
>> It presumes the recipient is processing the document for uniform
>> interpretation of presentation (i.e., what browsers do).
>>> Speaking of arguments, since you seem to disagree with the stated 
>>> objections and since you claim that every objection in this poll is 
>>> "demonstrably false" why not bring forward said demonstration? I'd 
>>> be thrilled to see proof of its existence as life would indeed be a 
>>> lot simpler if version indicators provided a usable solution to 
>>> versioning problems.
>> That is a paper tiger.  The issue is not about versioning problems,
>> let alone finding a universal design solution for versioning languages.
>> Issue 4 is "Should the new HTML language bear a version mechanism?" and
>> Issue 84 is "Should spec discourage use of legacy doctypes?"
>> There have been extensive discussions on the mailing list, including
>> many examples where an *optional* but standard way of indicating an HTML
>> language version is useful for authoring tools and systems that allow
>> workflows to be established based on such version indicators.  Such an
>> indicator is not intended to solve versioning in general -- it is intended
>> to record metadata about the rules followed during mark-up generation.
>> It is useful for any application of HTML that may process the language
>> differently (for its own reasons) based on the value of that indicator.
>> The fact that it is not useful for specific applications that intend
>> to provide uniform processing of all versions of a language does not
>> in any way detract from its usefulness for other types of applications
>> that have an equal right to influence HTML as a language.  Applications
>> that don't use the version will ignore the indicator.  Applications that
>> do use the version need to have a defined, compliant place to find it
>> in a standard way so that authoring and workflow tools built by
>> independent vendors can interoperate.
>> In regard to your argument:
>>> Versioning, as explained previously, is important enough that it 
>>> deserves to be done right. Yet some languages have taken a rather 
>>> naïve approach to it typically consisting in a version attribute on 
>>> the root element or other such simplistic schemes built on the 
>>> presence of a version indicator. That is fine if the purpose is to 
>>> die immediately when a given version is not supported (in which 
>>> case simply changing the namespace would be less verbose and just 
>>> as effective), but will not produce any useful effect if the intent 
>>> is to allow processors to work across versions.
>> Of course not, since that isn't the intent of the version indicator.
>> Version handling in HTML includes things like "ignore all unknown tags"
>> and other default rendering algorithms.  The version indicator in HTML
>> is only useful during the authoring process, wherein custom edit dialogs
>> are frequently enabled/disabled based on the chosen version, and custom
>> workflow actions can be triggered or alternatively processed based on
>> the chosen language version (usually in the form of strict validation
>> instead of non-strict, though there is no limitation on such processing
>> in general).
>>> Indeed, what is such a processor to do if it sees a version 
>>> attribute with a value greater than the version it supports?
>> Whatever it wants to do.  Browsers will of course want to ignore this.
>> Editing tools might dynamically load (and thereafter "know") a set of
>> instructions for version-specific handling, or they might simply adopt
>> the highest version they do support and highlight the language elements
>> that are not understood.  It is not the role of the language designer
>> to determine how all readers behave.
>>> Nothing useful comes to mind, short of warning the user that there 
>>> may be rendering issues, a message which said user will either 
>>> ignore, or will cause him to panic, but will not yield any useful 
>>> result.
>> Again, clearly written from the standpoint of a browser.
>>> Conversely, if the version attribute points to an earlier version, 
>>> should features from later versions be ignored? That would make 
>>> implementations unduly complex.
>> I suggest you consider what an editor would do with that information.
>> It is actually possible for an authoring system to attempt validation
>> of the same document according to every known variant of the language,
>> all in the background, and then provide a hint to the user if the document
>> is only valid under a later version.
>> And, no, this is not "unduly complex".  What would be unduly complex is
>> an authoring system that provides every potential language form to the
>> user, including options that are obsolete, when the user has already
>> configured the tool to only let them author in strict HTML6.
>>> Furthermore, if a language is extended in a modular fashion rather 
>>> than through linear versions, this approach breaks down with the 
>>> complexity of specifying the modules in use and their respective 
>>> versions.
>> Yes, which is why even modular frameworks end up being grouped together
>> at some point in the (standard) future and given a version indicator.
>>> When producing content, it is easily admitted that using the 
>>> smallest possible version that includes all of the needed 
>>> functionality is a good practice as it will enable the largest 
>>> usage by older implementations.
>> Only if you presume the earlier assumption that a version indicator
>> exists to cause the unknowing recipient to catch fire.
>>> But doing so properly requires authors to know for a given list of 
>>> language constructs which is the lowest version number that 
>>> comprises them all. That is asking a lot, and in practice authors 
>>> will likely fall back in such situations to using the highest 
>>> version number that they can get away with.
>> In practice, authors use tools.
>>> Either way, version information will often be out of synch (either 
>>> through error, or organic growth, or because the content is 
>>> composed from multiple sources) with the actual content. This 
>>> tendency is strong enough that relying on version metadata is 
>>> largely useless, unless applied to content that is exclusively 
>>> produced under tight control by programmatic means — a situation 
>>> that is exceedingly rare for web formats.
>> Actually, very little web content is produced via emacs and vi,
>> these days.  Most is generated using tools, translated from other
>> languages (that use strict versioning because they don't like entropy),
>> or dropped into fields within a template.
>> In any case, the purpose of the version indicator is to preserve intent,
>> which can then be mechanically checked against actual used syntax by
>> those few tools responsible for content maintenance.  If there is no
>> specific intent, then the version indicator is not used.
>>> But even without consideration that include hard to demonstrate 
>>> behaviour from putative users, the following very short decision 
>>> tree can be followed when looking at whether a version indicator 
>>> would be useful:
>>> Are processors expected to process content across version boundaries?
>>> No.
>>> Then each version is actually a different language (i.e. it is not 
>>> mutually intelligible). Just change the namespace (or if there is 
>>> no namespace, any other global indicator such as the root element 
>>> or media type and extension). You don't need a version indicator.
>>> Yes.
>>> The processors will have to be defined so that they can apply 
>>> lacunae values, language-level error handling, and other similar 
>>> rules intended to render unknown constructs sufficiently 
>>> intelligible. There is nothing which a version indicator could add 
>>> on top of what they already do. You don't need a version indicator.
>> Again, entirely based on the assumption that the processor is a browser
>> (or the equivalent read-only, uniform rendering machine that you refer
>> to as an XML processor).
>> ....Roy
Received on Saturday, 14 August 2010 03:04:00 GMT

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