Henri Sivonen wrote:
On Feb 18, 2009, at 16:15, Sam Ruby wrote:
Henri Sivonen wrote:
While HTML5 parsing as defined today supplies namespace information
for each element and attribute name, it doesn't supply
xmlns:foo-based namespace mapping context for resolving prefixes in
attribute content on the application layer.
If you could put aside your understandable dislike for prefixes in any
form for a moment:
How would renaming xmlns:foo="bar" to prefix="foo=bar" (or
whatever) address the issue you describe above?
Case xmlns:foo="bar" gets the following treatment:
With XML parsing and the XOM model, there is no attribute "xmlns:foo".
That is, there'd be no arguments for getAttributeValue() (on an Element
object) that would return "bar". However, getNamespaceURI("foo") would
return "bar".
With HTML parsing and the XOM model, getNamespaceURI("foo") would return
null. Depending on parser configuration, there either would be nothing
in the model corresponding to xmlns:foo="bar" or
getAttributeValue("xmlnsU00003Afoo") would return "bar".
Thus, the model would be inconsistent in the HTML and XHTML cases.
(Unless HTML5 parsing is changed to accommodate RDFa.)
Case prefix="foo=bar" would get the following treatment both for XML and
HTML parsing:
In XOM, getNamespaceURI("foo") would return null.
getAttributeValue("prefix") would return "foo=bar".
Hence, the model would be consistent in the HTML and XHTML cases without
changes to HTML5 parsing.
SAX2 would work in an analogous way.
XML is defined in terms of the W3C DOM. HTML5 is defined in terms of
the W3C DOM. Applications built only only W3C DOM interfaces can be
completely unaware of the differences between the HTML5 and XHTML5
serializations as long as they limit themselves to the non-NS-suffixed
APIs. Correct?
XOM and SAX2 are alternate mechanisms for accessing XML. I'm not aware
of HTML5 equivalents. But if there were equivalents for these two, it
is an open question as to whether such interfaces would behave the same
as if they were handing XML documents, or if they could be optimized
based on additional constraints on how attributes are used.
- Sam Ruby
