- From: Scott Luebking <phoenixl@netcom.com>
- Date: Fri, 19 Nov 1999 15:03:10 -0800 (PST)
- To: w3c-wai-gl@w3.org
A dynamic web page is one which is created just before being sent to the
user. The server which creates the web page basically gathers
information from one or more data sources like databases, XML documents,
real time data suppliers, dynamic data generators, etc; analyzes the
information as appropriate; decides the format to present the
information and then creates the web page in the format selected.
A key advantage to this process is that each web page can have such
aspects like content/information, layout/organization, etc, customized
or tailored to each user's needs or preferences. This technology will
be playing a key role as the web starts developing the more
personal/individual focus that Bill Gates described in his talk at the
recent Comdex conference.
The flexibility of generating web pages dynamically can be used to
benefit blind users to improve their efficiency when using web pages.
As Len Kasday has written:
" ... you can get optimal accessibility by generating pages
dynamically, tailored to the needs of the particular user "
This optimal accessibility is extremely important to blind users when in
competitive environments like work or school.
Static web pages, i.e. web pages which are created at an previous time
and then retrieved from storage when users request the pages, have an
inherent disadvantage in that it takes much effort to maintain different
versions of static pages. When information on one version is changed,
all the other versions also need to be changed. Unfortunately, this
provides opportunity for version skews to develop when accidently the
changes don't get added to all the versions.
The alternative to providing multiple versions of static pages is to
have a single static version which can support different types of users.
This strategy works unless the needs/preferences of the users are in
conflict with each other. For example, by the nature of web pages, they
have what could be called a "visual imperative", that is they often need
to be visually attractive/interesting and use the functions of vision to
navigate about the page. The web page designer usually relies on
aspects of layout, color, font, images, alignment to address the needs
arising from the visual imperative.
Unfortunately, some of those those attributes which web page designers
need to create visually interesting web pages can be in conflict with
the accessibility needs of the blind web page users. A significant
example of this type of problem is the use of tables, especially nested
tables, when creating visually appealing pages. Sometimes tables are
used to create visual symmetry where the left and right columns have a
similar structure and function while also serving as a frame around the
middle. Another example of tables is to create a particular construct
that is repeatedly used on the page. The repetition gives visual cuing
about what the construct would be used for while at the same time
enhancing the feeling of unity in the design. (Kind of like
alliteration in writing with the same sound being used repeatedly.)
When tables are used for layout, they add to the complexity of the
layout and can be hard for blind users to understand what is being
displayed in the tables while at the same not being very beneficial to
blind users. Blind web page users often prefer a layout which is single
column with the most important information at the beginning of the page.
A conflict here is that the extreme simplicity of the layout which is a
benefit for blind users is often limited in being visually interesting
and therefore at odds with the visual imperative of web pages.
On web pages where there is this type of conflict, decisions need to be
made. However, often the decisions are not in favor of accessibility
for blind users. The visual imperative is so compelling for a number of
reasons including business needs, small size of the blind user base,
etc, that it will be hard for a web page designer to give up what they
believe is visually appropriate for a web page in order to accomodate
blind users.
Dynamically generated web pages can help avoid these conflicts which can
occur in the development of "static" web pages. When a sighted person
requests a web pages which is generated dynamically, the server can
present the information in a format which is very graphically appealing.
Similarly, if a blind user requests the information, the server can
present the information in a format which will be more efficient for the
blind person to use. As a result, dynamically generated web pages avoid
the problem of compromising the visual imperative of web pages or the
accessibility needs of blind users.
It is helpful in a dynamically generated web page which is being
customized for a blind user that the layout take in consideration the
following:
1. a very linear format where information can be in order of
importance and grouped by functionality
2. Searching in a web page is much slower for blind people than sighted.
If the page is new, knowing what to search for is harder.
The page should be designed to help minimize the need to search.
3. Jumping back and forth on a page is much easier for sighted people
than blind people. The page should be structured to minimize
the need for that.
4. A sighted person can scan over a page which a blind person can't.
It is harder for a blind person to search a page based on concept
rather than eaxct words. If a web page is divided into categories,
it is easier for a blind person to decide what to look at.
5. Sighted people can often find the end of the form by some
visual cuing. Blind people often assume that encountering
a submit button is the end of the form. This can be in error
if there is more than one submit button or if there are more
form elements after the submit button. Blind users can benefit
from clear indication about the end of the form being reached.
6. A sighted person can quickly skip over a group of radio
buttons or identify which radio button is selected.
A blind person often prefers a drop-down selection list.
It is easier to skip over and the user can quickly identify
what the current choice is.
7. Decorative images can be left out since they can be distracting
to blind users with little useful information.
8. If the page is from a catalog where description is important, the
dynamically generated web page could have a detailed description of
the coat instead of an image on pages for sighted people. The
description should be integrated into the text flow for easier reading.
However, not only can the format/layout be chosen to be more effective
for blind users, additional features can be included when the browser
supports them. Here are some examples:
1. Both sighted and blind people need to get a sense of context from
each page. A sighted person can quickly scan to see what the page
is about. A blind person has to grope through the page
to get a sense of what is there in order to get a better understanding
of the context. This approach is slow and cumbersome. Also,
a blind person may jump to a conclusion to early. A blind person
can benefit from being able to hit a key and a summary of the page
appears in a pop-up box.
2. Sighted people can often find links more easily than blind.
If a page has some very popular links, it might be easier for blind
users to have keys activate the popyular links to reduce the
time searching.
3. It is often easier for sighted people to find forms on a
page than blind people. Blind users can benefit from having keys
which will automatically scroll the page to a particular form.
4. While sighted people can quickly skip over links at the top of
a page, it is harder for blind people to do that. An alternative
design would be to put groups of links at the bottom and have
keys which will scroll the page to the desired group of links.
5. Informational images might be better handled by having alert boxes
which have a long description that can be accessed on demand.
A question that could be asked is whether these suggestions listed above
make the web pages easier to navigate. The best way is to take output
from a search engine and rewrite it using the suggestions above. Then
try using the two versions with a screen reader and see what the
differences are. One way to measure efficiency is to count how many
keystrokes are needed to operate the browser/ screen reader combination
for each of the versions of web pages. (Doing a visual comparison of
the web pages can be informative, but will not show the full impact of
changes on blind people when using the web pages.)
A programmer who has programmed dynamically generated web pages will
find it fairly easy to program dynamically generated web pages
customized for blind users. If existing software is being used, it is
probably already set up to dynamically generate web pages of different
types. The structure of the web pages is usually fairly simple
consisting of text with form elements sometimes. Most of the time, the
programmer doesn't need to worry about such things as colors, fonts,
images, alignment of parts of the web page, etc. The simplicity of the
web page customized for blind users also means that teaching programmers
what is needed shouldn't be that hard in most situations.
Having dynamically generated web pages customized for blind users will
ease the burden of the web page designer. The designer won't have to
make compromises for accessibility, plus try to write the HTML so that
the results are accessible. It might even be a time saver since the web
pages for blind users are so simple.
Instead of the programmer creating alternate formats for blind users,
some combination of CSS, XSL, XSLT, XPath could be used. However, since
dynamic pages are generated to be used once and then discarded, it might
be easier to just generate the page initially in the desired format.
This would avoid problems of having to maintain different versions of
CSS, CSL, XSLT, etc, files. Also, it avoids problems of differences on
how developers may have written each tool, e.g. Internet Explorer
inplementing CSS differently than Netscape Navigator.
Why won't screen readers be able to do the same thing? The answer is
related to a current core limitation of computers. (My apologies to the
non-technical readers.) Computers have a hard time working with
concepts, especially given little information from which to extract the
concepts. Since computers have a hard time with concepts, they are
limited in what they can do in determining the purpose or intent of
something. This in turn means they have problems grouping things by
related functions or assigning importance to the functions. Until this
kind of problem is solved for computers in general, access technology
will have the same problems. Screen readers will have a hard time
deciding what is the most effient way to present the information since
it will have a hard time determining what is important.
For example, a web page has 40 links. Screen readers will have problems
categorizing the links functions. The result is that the blind user has
to slog through the links. It can be argued that blind users can do
that, but each time they are confronted with issues like that they will
be less productive and therefore less desirable in the workplace or less
competitive in academoic environments.
The issue of the concept-limitation of computers is often a hard one for
most people to recognize. This challenge is a key reason why the
concept of an expert system has migrated more to one of an assist
system. Computers are better at searching and conducting comparisons.
They are not as good at determining what should be searched for or what
needs to be compared.
I believe that web pages which are customized for blind users can help
avoid that "concept barrier" which will cause blind people to be less
productive and less competitive.
Received on Friday, 19 November 1999 18:03:51 UTC