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Way back in the olden days
when we were developing XHTML Modularization and then XHTML2, the
group recognized that there were lots of pieces of XHTML2 that were
generally useful and that it should be possible to publish them
separately. The concept was that since these were modules
they would be assembled by host language authors as needed, and
then at some point pulled together into XHTML2. Obviously
XHTML2 never came to be, but a lot of the pieces did get worked on
and pulled into other work (e.g., RDFa, Role, all sorts of stuff in
HTML5 although no one will ever admit that).
Today I wanted to talk about the Role Attribute. This piece
of XHTML2 is a deceptively simple attribute. It's purpose is
to help content authors label an element with it's role or roles
within a document. Why do elements have roles? Well -
that's complicated. First, some (more) history...
Sometimes W3C working groups have face to face meetings. At
one such meeting of the XHTML working group (at the AOL
headquarters in Virginia I think) a group member was wearing their
liaison hat between the XHTML working group and the group
responsible for accessibility. They REALLY wanted to be able
to have sections of the document labeled so that assistive
technologies (ATs) could more easily help people with various
disabilities use the web more efficiently. In particular,
things like navigation areas, headers, footers, content,
sidebars... and of course controls. The accessibility
liaison thought it was important that we define a base collection
of roles, but also that it be possible to dynamically extend that
collection of roles easily. The group thought this was a fine idea,
and added the role attribute to XHTML2. The base collection
has been modified over time - you can see its current form in the
Vocabulary Document.
Fast forward to today.
The W3C has today published the Role Attribute as a Candidate Recommendation. A lot has happened in
the W3C community since we started work on this simple attribute,
but the basic form of the Role Attribute and its capabilities has
not changed much at all. There is an attribute named 'role'.
It takes a list of zero or more values. These values
are either pre-defined TERMs (the things in that vocabulary
document), a URI, or a CURIE (a CURIE is a compact URI - a concept
defined by RDFa Core). Assistive Technologies can
use the values of role, in conjunction with other information from
the ARIA
Attributes, to more-or-less automatically make pages more
accessible. RDFa processors can use the information in role
attributes to automatically learn more about the semantics of a
page.
This specification is stable
now. The attribute works in all modern user agents now.
It's values are interpreted by many assistive technologies
already. It is already supported by some RDFa processors,
with more on the way. Even though the W3C says people
shouldn't rely upon stuff in Candidate Recommendations because they
might not be fully cooked yet, I say go for it. Role works
and it can't hurt. RDFa works well, and is processed by
popular search engines like Google and Bing. Telling the
browser (and any Assistive Technologies that might be looking at
the browser) what the role of the various parts of your web page
isn't just polite, it might help someone use your site more
effectively!
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Today the W3C published new versions of RDFa Core and XHTML+RDFa.
These versions are the result of 10 months of work by the W3C RDF
Web Applications Working Group, and are expected to be in their
nearly-final form. You can see the full announcement at http://www.w3.org/blog/SW/2012/01/31/new-rdfa-drafts-published/
You have three weeks to look these over and raise comments.
Otherwise, forever hold your peace. We look forward to
your input!
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After ages of development work and negotiation, the W3C's RDF Web Applications
Working Group is finally almost done with RDFa 1.1. This
seemingly simple, incremental change to RDFa 1.0 has taken about a
year longer than I expected it to, but the work is solid and has a
lot of community support. We pushed new working drafts recently of
RDFa Core 1.1, XHTML+RDFa 1.1, RDFa Lite 1.1, and the RDFa Primer. We are looking
for feedback on these over the coming weeks, with a plan to
progress to Last Call in mid-January.
P.S. Yes, I forgot that I had this blog I should be updating.
My bad!
P.P.S. Hooray for the Oxford Comma!
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The W3C's Protocols and Formats working group has been working hard
to accumulate the requirements for media accessibility. A few
months ago I took over as editor of the document. That
document has now been released as a 'First Public Working Draft' to
get feedback from the community. From the abstract:
This
document aggregates the accessibility requirements of users with
disabilities that the W3C HTML5 Accessibility
Task Force has collected with respect to audio and video on the
Web.
It
first provides an introduction to the needs of users with
disabilties in relation to audio and video.
Then
it explains what alternative content technologies have been
developed to help such users gain access to the content of audio
and video.
A
third section explains how these content technologies fit in the
larger picture of accessibility, both technically within a Web user
agent and from a production process point of view.
This
document is most explicitly not a collection of baseline user agent
or authoring tool requirements. It is important to recognize that
not all user agents (nor all authoring tools) will support all the
features discussed in this document. Rather, this document attempts
to supply a comprehensive collection of user requirements needed to
support media accessibility in the context of HTML5. As such, it
should be expected that this document will continue to develop for
some time.
Please take a look.
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After a couple of weeks of furious editing and publishing, the
XHTML2 work is FINALLY done! You can see most of the gory details
at the W3C.
What that article does NOT say, however, is that the working group
also completed its work on the RelaxNG implementations of XHTML and
XHTML Modularization. You can find that work as a free-standing
document.
Unfortunately, one thing that did NOT get updated is the XHTML
Media Types note. There are various corrections to this that were
pending, but in the end it was too difficult to get it published
before the end of the year. In the near future, I plan to publish
those changes independently (and maintain the document as guidance
to people who want to write XHTML and have it just work in current
user agents). You can see the latest
draft of this document if you are interested.
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It's been a long road. I first started working with the W3C and
it's XHTML2 (then HTML) Working Group on 27 August 1998. At the
time, I didn't know that it would become the work of 12+ years.
Sure, I had been involved in standards for a long time. I started
with the IEEE POSIX activity before it was even called POSIX
(anyone remember IEEEIX?) - sometime in 1985. That hobby spiraled
into a career, and has served me very, very well.
So, it is with some regret that I look to the end of my work on
XHTML at the W3C. We did a lot of good work. Some of that work has
been overcome by events, of course. This industry never sits still.
But, for the record, here are some of the important things this
activity developed and delivered:
HTML 4.01 - last updated
in 1999, but still the basis of most of the web.
XHTML 1.0 - the first
baby step toward a well-formed, valid web. At its inception, we
were all convinced that XML would rule the world, and HTML needed
to be based upon XML if it was to survive. We were a little bit
wrong.
XHTML Media
Types - a Note that explained how to deliver the new XHTML
documents to legacy user agents. Still relevant and widely used
today. We have a small update for it that might still get published
- you can see it here.
XHTML
Modularization - a set of building blocks and rules that
language designers could use. M12N is the basis for many activities
within and outside of the W3C. It continues to be used all over the
place. It started out being used only for XML DTDs, but was
expanded to XML Schema (finally published recently, but complete
for many years). In the next weeks we will release a final
installment of this, XHTML
Modularization for RelaxNG.
XML Events - a
declarative way to define events and bind them to elements and
observers. It's first version was published by the XHTML activity.
It has now been taken over by the XForms activity. I hope that they
will get XML Events
2 out the door at some point.
XHTML 1.1 - a tight,
XML-centric version of XHTML based upon XHTML Modularization. We
published an update to this last week, but it is a stable grammar
that can be used anywhere. It is also the basis for many extended
XHTML Grammars. The update last week makes it possible to validate
using XML Schema, and also to use the 'lang' attribute to improve
use of XHTML 1.1 documents by assistive technologies.
XHTML Basic - a
version of XHTML targeted at the mobile community.
XHTML Print - a
version of XHTML targeted at rendering consistently on
printers.
XForms - an independent
activity, but one that started within the XHTML activity.
XHTML+RDFa - another
independent activity. Originally a joint task force of the XHTML2
and Semantic Web working groups. The latest version builds up this
early work, but continues to take advantage of XHTML Modularization
for its definitions.
CURIEs - a compact
expression syntax for URIs. Used by RDFa, but also potentially by
other specifications that need to readily reference resources
without using long URIs in attributes.
The Role Attribute
module - an independent module to add a role attribute. Useful
for accessibility, but also for general semantic notation. This
work has been taken on by the Protocols and Formats Working
Group.
The Access module -
an independent module to add an access element. This element would
allow binding of 'keys' and events to elements. The original module
has no owner, but the general work has been picked up by the
Protocols and Formats Working Group.
XHTML 2 - a sweeping
revision of XHTML. This work was never completed, but will be
published in its current state as a Note.
XHTML
Modularization 2.0 - an update to the modularization framework
to accompany XHTML 2.
XFrames - an improvement
on traditional HTML framesets.
XHTML 1.2 -
a version of XHTML that added the role attribute, the access
element, RDFa, and ARIA. This was never a formal deliverable, but
was a logical extension of the work.
Wow. I have never typed that all out before! Along the way we
developed an entire publication infrastructure, including our own
internal markup language (xhtmlspec) for annotating sources. I am
proud to have served with my colleagues on this activity. I think
we did solid work. While some of this work will never come to
fruition, most of it was and will continue to be used throughout
the internet every day.
I will of course continue to work with this community going
forward. I remain active in the RDFa and Protocols and Formats
activity. I hope to assist ISO in its publication of the RelaxNG
Modularization framework. And I am keeping an eye out for the next
interesting 12 year project. And no, it's not HTML5!
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The web is getting better and better. Search is getting
smarter. Google's 'rich snippets' and Facebook's Open Graph Protocol are great
examples of how the industry is helping web developers make their
content more machine-readable. Industry-standard
'vocabularies' like FOAF, Dublin Core Terms, Good Relations, and
Schema.org are helping developers ensure that their content just
makes sense. And all of those technologies are based largely upon,
and designed to support other technologies that use, RDF.
What is RDF? RDF stands for "Resource Description Framework",
and an excellent overview of it is in the RDF Primer
the W3C has published. If you don't want to dig that deeply,
just know that RDF is a method for describing in a very standard
way the relationship between x and y. Moreover, it can also
describe the relationship between y and z. And so on and so
on, until you get all the way down to some well-known, standardized
'term' that has absolute meaning to something like the Google
search engine.
How is this useful? Well, it means in part that I can say
something like "Shane McCarron is the author of this article".
And, because the concept of an author is a well-known,
standardized 'term' that has an absolute meaning, and because this
article has a permanent URI, anything that can understand RDF will
immediately *know* this. Further, if I also say "Shane
McCarron" is identified by some other URI (e.g.,
http://blog.halindrome.com) RDF-aware processors will automatically
associate the author with that URI.
That's all great, I hear you saying. But how do I, as a web
developer, *tell* Google things about my web pages? Enter
RDFa. RDFa stands for "RDF in attributes" (some people might
argue about that, but I was in the room and that's what I
remember). It is a way to embed RDF information right into
your web page in a pretty straightforward way. And, if you do
it right, it means that search engines like Google and Facebook
will know *more* about your web site and its information than they
will know about your less-savvy competitors who don't bother to put
this data in.
There are a lot of great resources out on the web that can help you
get your annotations right. I have included a list of some at
the end of this article. However, just to get you started,
here is a simple example.
Let's say you have a picture you want to include on your web site.
You want people to be able to use that picture, but you want
them to know what it is a picture of and who took it. You
could say something like:
<span about="#myPicture">
<img id="myPicture"
alt="Cabin on the lake"
src="http://www.example.com/images/picture.png">
<span property="dc:title">Cabin on the lake</span>
by
<span property="dc:creator">Shane
McCarron</span>
</span>
In that example we use terms from the
"Dublin Core" vocabulary. These are well-known terms.
Any knowledge engine will know exactly what you are talking
about. If you wanted to be more explicit about who the
creator was, you might extend that definition like:
<span about="#myPicture">
<img id="myPicture"
alt="Cabin on the lake"
src="http://www.example.com/images/picture.png">
<span property="dc:title">Cabin on the lake</span>
by
<span rel="dc:creator"
typeof="foaf:Person">
<span rel="foaf:homepage"
href="http://blog.halindrome.com"
property="foaf:name">Shane
McCarron</span>
</span>
</span>
Now we have also
mixed in some terms from the "Friend of a Friend" vocabulary to say
that the dc:creator we talked about before is a "Person" who has a
"homepage" and a "name". These are also well-known terms and
will help the knowledge engines make better inferences about who
"Shane McCarron" is. If there are other things out there for
which a 'foaf:Person' with those attributes is listed as the
'dc:creator', they were likely created by the same "Shane
McCarron".
There are LOTS of ways to use RDFa in your
web pages and articles. I plan to write more on this in the
coming weeks. For now, here are some resources that can help
you get started.
General information on RDFa at http://rdfa.info/
The RDFa Primer
An interactive checker at http://rdfa.info/play/
Google's checker at http://www.google.com/webmasters/tools/richsnippets
Help for creating licenses at http://creativecommons.org/choose/
Information on vocabularies at http://www.schema.org/
Next up: How the W3C is using RDFa to help ensure its own documents
are well annotated.
RDFa
is (still) the best way to improve your SEO by Shane McCarron
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