Re: Support Existing Content (was: Proposed Design Principles review)

On Apr 29, 2007, at 7:50 AM, Murray Maloney wrote:

> At 04:09 PM 4/28/2007 -0700, Maciej Stachowiak wrote:
>> I agree the POV seems off. However, this principle has very important
>> implications for language design. How about like this:
>> Support Existing Content
>> SupportExistingContent: HTML5 should be designed so that user agents
>> conforming to it can still handle existing web content as intended.
>> In particular HTML5 should make it possible to process web documents
>> and applications via an HTML5 implementation even if they were
>> authored against older implementations and do not specifically
>> request HTML5 processing.
>> All changes and additions could cause some content to malfunction at
>> least in theory, but this will vary in degree. We need to judge
>> whether the value of the change is worth the cost. Cross-browser
>> content on the public Web should be given the most weight.
> I would feel better about this as a design principle if you used  
> the words
> that I sent you,

More specifically, here are my problems with your suggested wording:

> SupportExistingContent: The HTML WG will document the usage of HTML
> as it is practiced by popular web browers, and deployed on the web  
> and on
> intranets throughout the world. Our goal should be to facilitate  
> understanding
> of extant content, even in the face of unusual and unexpected  
> syntax or position.
> If any user agent is capable of an understanding an HTML construct,  
> it would
> be ideal for all user agents to be capable of that understanding.

1) Usage of HTML is not practiced by web browsers. I'm not sure it is  
grammatically correct to say it is practiced by anyone, but surely it  
is content authors who create specific HTML documents.

2) "Facilitate understanding of extant content" waters things down  
too much - we need existing content to behave and look basically the  
same in HTML5 UAs.

3) I'm not sure what "unusual and unexpected syntax or position" means.

4) Your last sentence is about interoperability, not compatibility; I  
agree with it but it does not belong in this principle.

> or you wrote words that related HTML 5 to extant HTML
> and left the implications as an exercise for the browser designer.

The fact that you did this is what waters down the principle too  
much, I think. The implications for browsers and other UAs are  
exactly what make this principle important, and I don't think it  
helps to leave that vague.

> I think that the meaning of this principle should boil down to "We  
> are not
> going to change the spelling of "align" or "p" or any other  
> language element
> that have come to be expected in desktop UAs, the web, or intranets  
> worldwide."
> Am I missing something?

Yes. Besides spelling, it is important not to incompatibly change  
behavior or appearance. For instance, requiring "p" to have no  
default margins would be unacceptable. Saying <input> with no type  
attribute should render as a button, not a text field, would be  
unacceptable. The principle really is very closely tied to what  
implementations will do with the spec.

> P.S. I am totally in support of defining a set of "Browser Design  
> Principles"
> I think that the world would be a better place if you guys could  
> agree on those.
> I would prefer that browser and language design principles not  
> become confused.

This one wouldn't even make sense as a browser design principle. If  
HTML5 requires things that are incompatible with existing HTML  
content, how could browsers use their HTML5 implementation to render  
today's content?

That being said, the rules for browsers are generally expressed as  
specifications. If the specs are precise enough, there is no need for  
additional guidelines.

I feel like there is some reluctance here to acknowledge that  
browsers exist, and to take explicit consideration of them in the  
design of the language. I don't think that makes sense - you can't  
design the web without thinking about the way most users are going to  
experience it.


Received on Sunday, 29 April 2007 22:54:56 UTC