XHTML and XForms

Steven Pemberton, CWI, Amsterdam and W3C
Chair, W3C HTML and Forms Working Groups

The XHTML Family

XHTML is a family of XML-based markup languages being designed.

Currently it consists of:

Example of XHTML running on a phone

An XHTML site from 1999 viewed on a mobile phone

XHTML 2

The new member of the XHTML family is in our minds the real XHTML.

Our aims are:

In fact, many of these things are intertwined.

Aim: Generic XML

By 'generic XML' we mean: if a facility exists in XML technologies, and it is suitable, use it and not a special-purpose XHTML facility. Try to get missing functionality added to XML.

Advantages: less variability; more interoperability; much of XHTML 2 works already; opportunity to make a cleaner break.

Aim: Less presentation

Remove all presentation-only markup.

Use stylesheets to define presentation.

Advantages: possible to author once, and display on different devices; better presentation possibilities; device presentation not hardwired; CSS has support for devices; more accessibility.

The power of CSS is currently seriously underappreciated.

(Note: doesn't require CSS to be implemented; just uses its model)

Aim: More structure

Add more semantically-oriented markup to make documents richer.

Examples: <l> element instead of <br>. <section> and <h> elements instead of <h1> <h2> etc

Not

I think that I shall never see<br>
A poem lovely as a tree

but

<l>I think that I shall never see</l>
<l>A poem lovely as a tree</l>

Advantages: more presentational opportunities (folding, marquee, numbering)
[More shortly]

Aim: More usability

Forrester Research did research on why people go back regularly to some sites and not others. They found only 4 important reasons:

(the rest is noise: 14% and lower)

More usability for: the author, the surfer

As an example of poor usability, current frames are a disaster! We are currently defining XFrames, a replacement for Frames.

Aim: More accessibility

One day we will all be grateful for accessible websites. Maybe even today.

The Kiss of the Spiderbot:

"Google is, for all intents, a blind user. A billionaire blind user with tens of millions of friends, all of whom hang on his every word. I suspect Google will have a stronger impact than [laws] in building accessible websites."

Karsten M. Self

Examples: more structure, navigation lists, better reatment of images

One day we will all be grateful for accessible websites. Maybe even today.

The Kiss of the Spiderbot:

"Google is, for all intents, a blind user. A billionaire blind user with tens of millions of friends, all of whom hang on his every word. I suspect Google will have a stronger impact than [laws] in building accessible websites."

Karsten M. Self

Examples: more structure, navigation lists, better reatment of images

One day we will all be grateful for accessible websites. Maybe even today.

The Kiss of the Spiderbot:

"Google is, for all intents, a blind user. A billionaire blind user with tens of millions of friends, all of whom hang on his every word. I suspect Google will have a stronger impact than [laws] in building accessible websites."

Karsten M. Self

Examples: more structure, navigation lists, better reatment of images

Aim: More accessibility

One day we will all be grateful for accessible websites. Maybe even today.

The Kiss of the Spiderbot:

"Google is, for all intents, a blind user. A billionaire blind user with tens of millions of friends, all of whom hang on his every word. I suspect Google will have a stronger impact than [laws] in building accessible websites."

Karsten M. Self

Examples: more structure, navigation lists, better reatment of images

Structure/Accessibility example

<h2>Chapter 1</h2>
...
<h3>Section 1</h3>
...

is now:

<section>
<h>Chapter 1</h>
....
   <section>
   <h>Section 1</h>
   ...
   </section>
</section>

More structure gives more accessibility.

Images

In designing XHTML 2 we decided to do away with a separate concept of an image altogether. Now we just say that there is an equivalence between an external resource and an internal one. For instance

<table src="temperatures.png">
<caption>Average monthly temperatures</caption>
<tr> <th>Jan</th> <th>Feb</th>....
<tr> <td>0</td>   <td>-4</td>...
</table>

A browser that can do images will display the image; others will display the table.

Advantages: device independence, accessibility, and even usability (since if the image is unreachable the document is still useful.)

Aim: Internationalization

Aim: Less scripting

Observe how scripting is currently used.

Identify missing markup/functionality.

Add it where possible; try to cover 80% mark

Examples: menus for navigation; forms data checking; folding presentation.

Advantages: more devices, more presentational variations, better search, better accessibility

Aim: More device independence

With an aim to single authoring

E.g.

Events

Current HTML events are a disaster

XML Events addresses these.

<a onClick="...javascript..." ...>

becomes

<a ev:event="activate" ev:handler="#hdlr" ...>

XForms

The Model

The Model contains a number of things:

The Model (more)

The User Interface

The User Interface binds into data in an instance.

The XForms set of UI controls are abstract controls, representing the intent of the control, not its look. You can then use CSS etc., for generating a presentation.

This means (amongst other things) that you can generate different presentations for different devices from the same form.

Control Example

For instance a select1 represents the notion of selecting a single value from a list. It can then be rendered as

You can even use different presentations for different devices.

XForms Demo

We are close to PR status. Three implementations taking part in interoperability tests. We know of more than 20 implementations currently, and some emerging large user groups.

(See conference exhibition for an example)

Conclusions

HTML was originally designed as a structure description language, not a presentational language.

The design of XHTML is truly 'radical': taking HTML back to its roots.

Device independence, accessibility and usability are surprisingly closely related.

Even though website builders may not yet know it, device independence, accessibility and usability have a major economic argument in their favour. Spread the word!

More information: www.w3.org/Markup,www.w3.org/Markup/Forms