Introduction to accessible web development
Why are we concerned about accessibility?
- Legal reason: Section 508, 504, Title III (U.S.), similar laws worldwide.
- Real reason: human needs, described by the World-Wide Web Consortium
2.0 principles. Web sites must be:
- Perceivable in whatever mode a person can use (video, audio, braille, etc.),
- Operable by whatever means are available to the person (keyboard, mouse, etc.),
- Understandable within the person's ability, and
- Robust enough to work with different present and future web technologies.
What do we have to do?
- Make accessibility an integral part of our development process.
- Since barriers on the Web are not obvious like stairs,
guidelines tell us what "ramps" are needed for web users.
How do we do it?
- Four-stage mental model of the development workflow, platform independent. All but the
first stage employ WCAG
2.0 sufficient techniques.
- Content: raw material, not yet organized, possibly in text or other forms.
Not accessible or usable by anyone.
- Structure: content organized in logical order, structure
marked up for the computer in HTML. The most important level, accessible to
everyone even if not pretty yet.
- Markup is used by assistive technology, especially alt-text, headings mode,
list mode, forms mode.
- Presentation: primarily the visual component, specified for the
computer in style sheets (CSS).
a similar language. Enhancement for those who can use it, but must be designed carefully.
- We'll illustrate with the fictitious University of
Lompoc home page.
When is it right?
- If a Web site meets the Level "A" WCAG 2.0
success criteria, it meets most human needs and the legal requirements
of U.S. Section 508.
(see Prof. Wayne Dick's proof
of this statement).
- No automatic software program can verify this; it takes human intelligence. We use a variety
of techniques including a simplified standards-based protocol that we call
(Demonstration to follow; draft review form is also available.)