W3C Workshop on Metadata for Content Adaptation - October 2004
Position paper prepared by
Al Gilman
As an individual. This material has not been reviewed by nor
consensed on by the Protocols and Formats Working Group or anyone else
representing the W3C or WAI.
Mapping the demand and
supply properties domains to the point of interoperation
Take-Aways
Meta-Negotiation: sharing decision capability information,
negotiating binding responsibilities
Mark Birbeck, speking at the 2004 W3C Technical Plenary, raised the
idea of "Defer decisions when you know downstream processors can handle
them." This leaves us with two questions: How can the
upstream processor know that the downstream processor can handle this
decision? How much does the upstream processor need to know to
trust that the downstream processor can handle this decision
better? There is clearly risk, from the perspective of the
upstram decision process, in deferring. So there has to be a
material expectation of gain (better results) to offset this.
Data thesaurus: compare and contrast of terms and scales incumbent
in demand (UI, preferences) and supply data domains
In principle we could compare and contrast and reduce until we had
accomplished a definitive mutual data normalization for the property
terms used in user interfaces and their adjustments and in media
objects and their transforms. But not fast. For the near
terms we need to begin to recognize where scales touch aspects in
common and roughly how they map. Because initially we will have
much more oppotunity to adapt at the server out of information entered
for other reasons at the client, and to rescue a failing presentation
on the client with the aid of gross choices and rough characteristics
available from the server, not everything you ever wanted to know.
What's Old
Author Proposes, User Disposes
In the Device Independence Concepts, a distinction is drawn between an
optimized presentation and a functional presentation. The point
is made that the user should be given the option of re-binding UI
effects so as to restore a functional presentation if what someone had
thought would be an optimized presentation is not going to work at
all. Giving the user control over presentation options has been
developed in the User Agent Accessibility Guidelines [UAAG10], and
providing the assets needed to populate these alternate views in the
Web Content Accessibility Guidelines [WCAG10, WCAG-WG]. In the
development of W3C Format Specifications, where a format was about to
violate these principles the Protocols and Formats WG has generally
been able to gain remedies by appealing to these principles [someWAI].
A Rationalized Development Process Aids Multi-Channel Delivery
Let's just hit the high spots:
- Re-use constituents of content appropriate to applications
- Re-use assembly patterns appropriate to delivery contexts
- Reduce data errors or conflicts
- Reduce missing features in dialog facilitation (menus, links,
etc.)
This applies to serving uses with different devices, and it applies to
serving users with different needs and preferences. This is
recognized in the work of the Device Independence Working Group and of
the Authoring Tool Accessibility Guidelines Working Group.
What's New
Disaster Management adds a Market
Recent attention has focused on infrastructure for public information
in emergencies and particularly disasters - emergencies affecting large
numbers of people and quite possibly affecting the communications
infrastructure as well. Here is an application where a
command-and-control communications and intelligence infrastructure has
to be rapidly configured out of assets of opportunity - what terminal
devices people actually have and pay attention to - and what
communication network assets survive. A functional presentation
is what is desired, not spit and polish. In its requirement for
"readiness to operate in alternate modes" it is almost exactly like
accessibility in its push to build Device Independence capability into
a broad range of information dissemination systems.
Education has a Proposal for us
Since the last time I got to discuss this with many of you at WWW2003
[DevDay], the education community has made considerable strides in
bringing forward proposals for accessibility metadata [IMS
ACLIP]. This material has to be considered and compared with the
spectrum of needs across different applications and particularly the
decisions involved in optimizing a presentation to the level of being
commercially competitive. But the bottom line is still "Here's a
way to do it. Best it or use it."
Analysis
Decisioning: Think Globally, Act Locally
Cascading Style Sheets is set up on the premise that 'rendering' takes
place one 'canvas' at a time. I have been trying to assert that
decisions about styling, what presentation effects to use to represent
which content distinctions, should be decided from a broader
perspective to meet WAI needs. I finally think that I have the
'toy example' it takes to explain why. This is the sheaf of cards
that is sent to a WAP1 browser, if I recall correctly. Here there
are a tuple of views. Always the same kinds of views. Part
of the user interface is knowing what aspects of a situation are
addressed in what views. In such a delivery context, there are
things that have to be emphasized or distinguished to the user.
But not in all views. Some distinctions will be prominent in one
view and suppressed in another, because the aspects emphasized in each
view are comprehended by the user after a few dialogs. A screen
reader session works much the same way. There is a screen-review
view, a list-of-links view, a tables mode and a forms mode. Each
of these views has its own listen and feel. It doesn't make sense
to make un-coordinated presentation policy decisions in each view; the
criticality of a given distinction for the aspect at the heart of each
view should be considered in allocating vocalization effects to
different qualities of the content.
That's fine in principle. What could be done about it in
practice? Perhaps the user-defined test variables in SMIL give us
a clue. The global analysis could create an allocated climate of
decision-conditioning parameters for the styling of each canvas, or a
profile of content-model properties to be exposed (with emphasis
gradations) in each sub-view. This is a wild guess, but that is
an example of how global conditions are conveyed to local decisions in
one W3C technology.
Warning: The term 'delivery context' could get us talking past one
another
A naieve or demand-side reading of that term would mean the conditions
under which the user interaction takes place. Yes it includes
devices, user, and environment. But it includes all aspects of
these that could fuel a better adaptation, and to enough precision so
that more information would not lead to better results.
If I have it straight, the way this term is used in the Device
Independence documents, it referes to a collection of parameters which
contribute some information about selected aspects of the 'delivery
context' as conceived in the first paragraph above. There is no
warrantee as to how precisely, how accurately, or how thoroughly.
For the purposes of this workshop, I think we need to keep in mind that
there is an approximation relationship between these two, and it is the
proper business of the workshop to enquire whether there are aspects
that should be better covered in order to yield a more effective
adaptation end-to-end or a more cost-effective negotiation of what
adaptation gets done where. So somehow we need to devise a
provisional vocabulary that will allow us to talk about either of the
above concepts and not get confused about which we are addressing.
Optimization uses finer characterization of [supply, demand]
properties than survival does
Accessibility is an 'ility' and tends to ask the questions: "Is there a
way to achieve a functional presentation? Can the user steer the
process into such a configuration? On the other hand, the
commercial customers of Device Independence techniques are generally
interested in having their services presented in a way that is
competitive with other services hand-crafted for each of the several
channels addressed. [With important deviations, such as
enterprise functions, hospital infrastructure for patient orders,
etc.] However I will persist in the generalization. To do
the Device Independence job, you prepare a variety of image options and
you are seeking to select the best one for the current delivery
context. So you need to know enough about each to understand the
tradeoffs down to the point of "which is best." This is more
information that what is generally needed to discover "is there one
there that I can make do?"
My prejudice would be that we should go ahead and use the more
fine-grained scales that address the commercial demand where they
exist, and infer functional success or failure from abstractions of
these finer properties. This still may leave the accessibility
community seeking coverage for aspects, such as interpretation of
words, that aren't yet covered by commercial practice in multi-channel
delivery of services. [But globalization is a tide floating
translation and internationalization boats.]
Bits and Pieces
User runs out of 'contrast' adjustment
This may be apocryphal, but somewhere I think I heard that the DI
concept (or is it the current core presentation properties schema)
doesn't address environmental factors. Here is a little use
case. Suppose a user is using a graphical PDA in a situation
where there is a lot of glare from the environment and the screen is
hard to read. No, the device doesn't have an ambient glare
sensor. But if the user exercises the contrast control repeatedly
until running out of adjustment capability, we might reasonably infer
that a content adaptation would be appropriate. An upstream event
asking if the upstream processes could format the material to be less
dependent on device contrast capability might bring down a
high-contrast version that would save the day.
'Usable at' size range
At present we have content asserting a fixed size for itself, in the
area of images. In actual practice even pixel-array images are
zoomed by screen magnifiers and in other situations as well.
Vector graphics are inherently scalable in terms of device
capabilities, but still aren't usable below a given size. The
accessibility problem -- can we get to a working adaptation -- would be
advanced if we could get images rated as to the min and max size over
which range they constitute a 'functional presentation.' This
doesn't have to keep us from setting a 'best at' size property, but it
would help to understand what range of transformations they would
tolerate reasonably well, and what transforms could be know ahead of
time to be useless. It could help in optimizing page layouts as
well, such as guiding the rollover between full image and line-drawing
morphs.
Even checkpoints (success criteria) can be too coarse for some uses.
There is a use in the educational arena as follows. The
instructor in a course is using SCORM [SCORM] educational modules as
assignements for her students. One of the students in the course
has a disability. One of the modules the instructor would like to
use has problems for this individual. How can the instructor find
an alternate assignment to reach the same educational objectives?
Here it may be overly broad to know "this module is missing text
equivalents for some non-text media objects." For a specific
student, it may make all the difference in the world whether the media
objects missing their alternatives are visuals or audio tracks.
When there is no course-level sequence that a) follows the instructor's
tailored syllabus and b) meets the needs of all students for all
lessons, then it is reasonable to try to rescue off the scrap heap
module-by-module enough lesson plans to put together an alternate
course of study that works for this specific student.
Readings
[UAAG10]
User Agent
Accessibility Guidelines 1.0
[WCAG10]
Web Content
Accessibility Guidelines 1.0
[WCAG-WG] The Web Content Accessibility Guidelines
Working Group is working toward a
second-generation WCAG.
[someWAI]
some
WAI comments on Device Independence
[DevDay] collected presentations from the WWW2003
Developers
Day Track 6
[IMS ACLIP] IMS AccessForAll
Meta-data
Specification
[SCORM] Shareable Content Object Reference Model Initiative (
SCORM )