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Re: [SVGMobile12] Error handling is a "SHOULD"?

From: Ian Hickson <ian@hixie.ch>
Date: Wed, 21 Sep 2005 21:28:47 +0000 (UTC)
To: Jon Ferraiolo <jonf@adobe.com>
Cc: www-svg@w3.org
Message-ID: <Pine.LNX.4.62.0509212108441.423@dhalsim.dreamhost.com>

On Tue, 20 Sep 2005, Jon Ferraiolo wrote:
> This is the SVG Working Group response to your comment found at:
>   http://lists.w3.org/Archives/Public/www-svg/2005May/0144.html
> With more recent versions of the SVG spec, we have changed the wording and
> believe it addresses the problems that have been identified. It now says:
> -------------------
> When a document is in error, the User Agent shall provide a highly 
> perceivable indication of error. The following error handling behavior 
> represents a recommended approach that User Agents may choose to 
> implement: [...]

Are user agents also allowed to (in addition to showing a "highly 
perceivable" indication of error, such as, I assume, an entry in the 
browser's error console), make error recovery attempts?

Most SVG UAs today seem to use error recovery with no error indication at 
all, which has led to significant amounts of SVG content having errors 
(most commonly errors as serious as missing namespaces). This content 
renders in UAs because they have all been reverse-engineering each other's 
error recovery rules (I am aware of this having occured several times in a 
couple of UAs, and it seems safe to assume it has happened with other UAs 
too). Could the working group please clarify whether this behaviour is 
acceptable or not? If it is acceptable, could the working group please 
specify how a UA should recover for each case of the document being in 
error? This would avoid requiring UA vendors to reverse engineer other 
UAs, a situation that has led to the current Tag Soup mess with HTML.

> We did not feel it was appropriate to define a required approach to 
> error handling because implementation experience shows that this is a 
> difficult implementation area

On the contrary, it is my opinion that it is specifically with the 
difficult implementation areas that the implementors need the most 

It is therefore my opinion that this does not address my concerns.

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Wednesday, 21 September 2005 21:28:57 UTC

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