[whatwg] Clarifying the use and requirements of Data URL

[Ian Hickson]

On Wed, 18 Aug 2010, Peter Beverloo wrote:
>
> Currently the specification requires the use of Data URLs for 
> canvas.toDataURL[1] and refers to usage of them a number of times as 
> well[2][3].  While steps describing how to generate a Data URL are 
> defined in the specification[4], they are not being referenced by the 
> other occurrences.  These steps seem to be identical to the contents of 
> RFC 2397[5], "The "data" URL scheme" by Larry Masinter.
>
> [1] http://www.whatwg.org/specs/web-apps/current-work/#dom-canvas-todataurl
> [2] http://www.whatwg.org/specs/web-apps/current-work/#submit-data-post
> [3] http://www.whatwg.org/specs/web-apps/current-work/#sandboxOrigin
> [4] http://www.whatwg.org/specs/web-apps/current-work/#submit-data-put
> [5] http://tools.ietf.org/html/rfc2397

The steps you cite as [4] have now been removed.


> Next to that, the specification does not list when Data URLs should be 
> supported by an User Agent. WebKit, Gecko and Presto seem to accept them 
> as any resource, including locations entered via the address bar, while 
> Trident only accepts Data URLs for images and scripts.

That seems out of scope of the specification. Which protocols a user agent 
supports is a matter for the specifications of those protocols, not a 
matter for the HTML specification.


> I believe the use and requirements of Data URLs in the specification
> could be clarified by:
>   - Referring to RFC 2397 for information about their composition and
> syntax *or* generalize the steps described in the form submission
> algorithm[4], so they can be applied on the entire document.

I believe proper reference is now made to the RFC wherever relevant.


>   - Extend the accepted values of @src, @href, @action et al to
> include support for data: URLs.

Support for data: is required to the same extent as support for http: is 
required in those contexts.


On Tue, 24 Aug 2010, Julian Reschke wrote:
> On 18.08.2010 15:21, Peter Beverloo wrote:
> > Currently the specification requires the use of Data URLs for
> > canvas.toDataURL[1] and refers to usage of them a number of times as
> > well[2][3].  While steps describing how to generate a Data URL are
> > defined in the specification[4], they are not being referenced by the
> > other occurrences.  These steps seem to be identical to the contents
> > of RFC 2397[5], "The "data" URL scheme" by Larry Masinter.
> 
> I raised <http://www.w3.org/Bugs/Public/show_bug.cgi?id=10399>, but it 
> appears Ian thinks that not citing RFC 2397 is ok.

That was for a different section, which no longer exists (and for which 
citing the RFC normatively was superfluous, since no normative conformance 
criteria from the RFC applied to that section).

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'