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Re: What is Dynamic Content?

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From: Jukka K. Korpela
Date: Jan 1, 2003 7:28AM

On Tue, 31 Dec 2002, Frank Gaine wrote:

> could anyone give me examples of 'dynamic content' as it
> relates to 6.2 of the WAI Checkpoints?

The techniques notes that the checkpoint refers to
discuss applets and "programmatic objects", frames, and
scripts, but it's difficult to say what kinds of content is
really regarded as dynamic here. The glossary of the document
does not define "dynamic", except in the sense that the phrase
(marketing term) "Dynamic HTML" is described.

(Guideline 4 says: "Clarify natural language usage", but the
more specific guidelines, or "checkpoints" as they call them,
are rather technical in nature and miss the most important point:
terms that might not be understood by readers or that might
be misunderstood should be defined or explained, within reasonable
limits - and phrases commonly used as vague buzzwords surely
fall within the limits. The guidelines document itself actually tries to
explain the terms it uses, via the glossary mainly, but there are
important omissions, like "dynamic content".)

Etymologically, "dynamic" (from Greek "dynamis" 'power, force') means
'powerful, powered'. But it's become a buzzword that often means that
something _changes_. (The connection is that changes can often be thought
of as caused by some force.) In the Web context, some kind of interaction
is usually implied, either with the user or with something external to a
Web page, such as a database, newsfeed, or camera. So it could be almost
anything; it's the opposite to a static page, such as a simple HTML
document, the content of which does not change unless edited by the page
author. (This is a bit odd. A page is probably considered as "dynamic", if
it is generated from a database whenever a browser requests for the page,
and "static" if it is changed only so that a person edits it directly.
Yet, the actual update rate could be once a year for the former, once a
day for the latter.)

But in the context "Ensure that equivalents for dynamic content are
updated when the dynamic content changes", we probably need no go very
deep into this conceptual mess. It actually boils down to a simple
principle that can be written more generally: Make sure that the fallback
content (to be used in graceful degradation) is as up-to-date as the
primary content. For example, if you write an applet, you should specify
an adequate fallback for non-Java presentations (though, in special cases,
the fallback content could be empty, just as alt="" can be adequate);
checkpoint 6.2 reminds that if you change the applet, you should also
change the fallback accordingly.

The practical importance of this rule stems from the fact that even if
authors realize why fallback content is needed, they often tend to regard
it as something extra, to be handled with the little finger of one's left
hand (oops, I mean 'less skilled hand' :-)). It's easy to forget to update
it when in hurry and rush, i.e. in the normal condition of Web authors.


--
Jukka "Yucca" Korpela, http://www.cs.tut.fi/~jkorpela/


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