Post on 10-Apr-2018
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Why HTML5?Why not XHTML2?
Learning from history how to
drive the future of the Web
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Michael(tm) Smith
mike@w3.org
http://people.w3.org/mike
sideshowbarker on Twitter, GitHub,&c
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HTML Working Group
Web Applications WorkingGroup
CSS Working Group
SVG Working Group
more...
W3C Interactiondomain
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From 1997 through
the end of 2006, work
on HTML within theW3C focused
exclusively on the XHTML dialect .
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A government inexile...
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From June 2004 to
March 2007, work on
the (non-XHTML)HTML language took
place outside of theW3C .
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About HTML5 (and HTML forms)...
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HTML5 in the words
of the W3C HTML
WG...
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HTML designprinciples
http://w3.org/TR/html-design-
principles/
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HTML design
principlesSupport existing contentEnsure interoperability
Precisely define UAbehavior
Handle errors (non-
draconically)
Evolution not revolution
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³Draconically´=
³Draconian´=
³catch fire and fail´
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About XHTML2 (and XForms)...
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XHTML2 in the words
of the W3C XHTML
WG...
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XHTML2 Design Aims
http://w3.org/TR/xhtml2/introduction.html#ai
ms
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XHTML2 Design
Aims U se existing XML facilities
rather than duplicating them(implies namespace support)
Less scripting (vs declarative
approach )
I ntegration with Semantic Web
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What does³declarative´ mean?
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Declarative programming
success story: SVG
(XSLT also? XForms?)
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HTML5 and XHTML2 in contrast...
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Things HTML5 doesn¶t
doDoes not favor XMLfacilities
Does not avoid scripting
Does not consider
integration with the
SemWeb a priority
No arbitrary namespaces
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Things XHTML2 did not
do Does not support existing
content in the same way that
HTML5 does Does not precisely define UA
behavior
Does not handle errors non-
draconically (uses ³catch fire
and fail´ error handling)
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Important point:
XHTML2 was adifferent language than
XHTML1
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...³different language´ in
that XHTML2 does notfully support existing
XHTML1 content (notbackward compatible)
rtant point: XHTML2 isa different language
than XHTML1
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A representative statement aboutthe difference in philosophy:
³HTML is the assembly
language of the Web.´
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Important point: In some
cases HTML5 offers a
choice of both declarative
and scripting
approaches.
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About error handling...
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Well-formed XML:<input disabled ="disabled">
E mpty attribute: <input disabled > Without quotes: <input value=yes>
Single quotes: <input type='checkbox'>
Double quotes: <input name="be evil">
Which of these are errors?
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<i><b>misnested
tags< /i>< /b>
This is a real error
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HTML5 parsers can
handle real errorsinteroperably and
gracefully.
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Why is it important tohandle errors?
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More than 93% of
Alexa Top 500 sitescontain HTML
conformance errors.
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A little history...
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(About draconian error handling in XML)
I think users and application builders
should have a choice with what they
do with invalid data... I therefore
plan to continue to provide it even if the spec says that this is non-
conforming.
April 1997 I think users and application builders should have a choice with what they do with invalid data.
I cannot see how a user or application builder can be disadvantaged by being provided with this choice, and I
therefore plan to continue to provide it even if the spec says that this
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After careful consideration, theHTML Working Group has decided
that the goals for the next generation
of forms are incompatible with
preserving backwards compatibility
with browsers designed for earlier
versions of HTML.
August 1999
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W3C has no intention to extend
HTML 4 as such. Instead, further
work is focusing on a reformulationof HTML in XML
November 1999
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...while the ancestry of XHTML 2
comes from HTML 4, XHTML 1.0,
and XHTML 1.1, it is not intended to
be backward compatible with its
earlier versions
August 2002
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XHTML 2.0 seems to me the live
proof that something is going wrongat W3C... I strongly suggest
dropping all XHTML 2.0 efforts in
favor of a new ³xHTML 5.0´language. Clearly a successor to
HTML 4, feature-oriented, made for
the web.
December 2002
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The W3C had so far failed to
address a need in the Webcommunity: There is no language for
Web applications... I intend to do
something about this (hopefullywithin a W3C context, although that
will depend on the politics
of the situation).
January 2004
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The dream of a new web, based on
XHTML+SVG+SMIL+XForms, is justthat ² a dream... The best way to
help the Web is to incrementally
improve the existing webstandards... so that web content
authors can actually deploy new
formats interoperably.
June 2004
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We need to specify error handling
behavior to ensure interoperability
³even in the face of documents that
do not comply to the letter of the
specifications´.
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Authors will write invalid content
regardless of what we spec. So the
spec states ³what authors must notdo, and then tells implementors what
they must do when an author
does it anyway´.
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It is necessary to evolve HTML
incrementally. The attempt to get the
world to switch to XML, including
quotes around attribute values and
slashes in empty tags and namespaces
all at once didn¶t work...
October 2006
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more HTML history
http://w3.org/html/wg/wiki/Histo
ry
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HTML5 has a major focus
on facilitating use of a
browser as a Webapplication platform (or
Web application runtime
environment).
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XHTML2 had a major
focus on providing a
general-purpose documentlanguage with declarative
mechanisms to enable
interactive features.
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HTML5 support specific native browser
support being implemented
by all major browser vendors
spec remains in activedevelopment
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XHTML2 support no specific client-side native
browser support from any
major browser vendor
« but was intended to be
possible to ³bolt on´ some level
of support using CSS+JS
last WD: 2006
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The bottom line...
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HTML5 is the only
HTML dialect that will
be natively supported in
browsers on the client
side.
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S ome HTML5 differences...
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HTML5 defines HTML as an abstract
language with two standardsyntaxes supported by browsers:
a text/html syntax, with parsing rules defined by the HTML5 spec
an XML syntax, with parsing rules defined by the XML spec
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Similarly, applications can
potentially represent HTML in
memory in any number of ways.
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http://software.hixie.ch/utilities/js/live-dom-viewer/
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However, there¶s only one standard
in-memory representation supported
by browsers: The W3C DOM.
The HTML5 spec precisely defines
the DOM representation that
browsers must use to represent
HTML content in memory.
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<!DOCTYPE html PUBLIC"-//W3C//DTD XHTML 1.0
Transitional//EN"
"http://www.w3.org/TR/xhtml1/
DTD
/xhtml1-transitional.dtd">
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<!DOCTYPE html>
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<meta http-equiv="Content-Type"
content="text/html; charset=utf-
8">
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<meta charset="utf-8">
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I mportant point:
HTML5 includes XHTML
(but not XHTML2 ...)
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Frequently Asked
Questions (FAQ) about
the future of XHTML
http://www.w3.org/2009/06/xhtml-
faq.html
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Ez minden.That¶s all.
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Köszönöm szépen.Thanks.
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Michael(tm) Smithmike@w3.org
http://people.w3.org/mike
sideshowbarker on Twitter, GitHub,&c