RE: ISSUE-41/ACTION-97 decentralized-extensibility

On Thursday, October 01, 2009 11:53 AM, Maciej Stachowiak wrote:
> On Oct 1, 2009, at 11:05 AM, Adrian Bateman wrote:
> > Currently, IE doesn't support the DOM APIs related to namespaces.
> > Currently the other browsers support these APIs but don't have a
> > mapping to the HTML serialisation (and don't process the xmlns in
> > the way IE does). This proposal aims to bring the two together. It's
> > true that we're not aware of a current implementation that does both.
> 
> Besides the different DOM, IE doesn't seem to do any namespace
> processing of attributes. Thus, the following paragraph in the
> proposal seems incomplete:
> 
> "The proposal as stated closely matches behavior that Internet
> Explorer has had for a number of releases, reducing compatibility
> concerns. While true that Internet Explorer does not currently allow
> prefixes to be defined anywhere other than the root element in the
> document, lifting this restriction is not believed to present any
> significant compatibility risk."
> 
> There seem to be a lot of differences besides lifting the root element
> restriction.
> 
> It would be good to document what IE actually does, so we can clearly
> understand the differences and assess the compatibility impact.

IE has some arbitrary restrictions today. Most of these are based purely on limitations in the implementation of our current DOM and what we proposed removed those restrictions (for example we had nowhere to store the namespace relationship on our attributes).

We talked about many of the limitations in the discussion with the HCG:
http://lists.w3.org/Archives/Member/w3c-html-cg/2009JulSep/0075.html
http://lists.w3.org/Archives/Member/w3c-html-cg/2009JulSep/0086.html

The key differences:

* We don't support nested namespace declarations where one should override another
* We don't support the namespaces on attributes
* We only allow prefix declarations on the root element

These were generally limitations from a time/resources perspective rather than a conscious choice for compatibility. Of course, they could be considered as alternatives to the proposal document.

Regards,

Adrian.

Received on Thursday, 1 October 2009 20:25:07 UTC