RE: Server Side Magic.

I'd just like review some of the comments on this thread and my own two
pence. As I see it there are two ways of making content available on
multiple devices - content specialization and content generalization. 

If we momentarily forget there are devices that do not understand HTML then
content generalization becomes an attractive strategy. Specifically there
has been a lot of work done by the W3C on accessability under WAI. This work
is highly relevant to multiple device delivery - for example the use
alternate text, avoiding the use of frames, the use of stylesheets and
providing a document that degrades to a sensible serial form are all useful
techniques. As Tom points out pages using these techniques are much more
likely to be usable on PDA style devices. The downside of this approach is
lots of people need to support devices that do not support HTML When WAP 2
comes out and more devices use XHTML / CSS, this approach will have wider
applicability. 

Then there is the content specialization method using XML / XSL in an
architecture like Cocoon. This has the advantage that it can target multiple
devices that understand multiple languages so lots of people are using this
approach. However IMHO writing XML / XSL is harder than writing HTML.
Specifically if you want to avoid the situation of having a stylesheet for
ever page (p) and every device (d) i.e. p*d stylesheets you need to
introduce some abstractions. Typically this involves use of techniques like
modes or generation of stylesheets via stylesheets in XSLT. These are
complex programming techniques that are hard for content authors. There are
ways of overcoming this; one way is replacing adhoc user defined XML with an
XML compliant standardised device independent markup language. This means
choosing abstractions and writing stylesheets for devices will only need to
be done once so the content authors can get on with writing content. I think
this is what Juha was referring to in his original post. As far as I know
there are no open languages like this although some members of the W3C
device independence working group have expressed the opinion that they would
the WG to develop one. 

In addition to this there's the issue that the current generation of WAP
phones suffer usability problems and vary widely in how they implement the
WAP standard. This means that it is very hard to create a site in WML that
will work on all phones, never mind XML / XSL. Architectures like Cocoon are
not a magic bullet for this - unless you want to write a stylesheet for
every device. As the WAI activity has highlighted, accessability is just as
much the responsibility of the person who wrote the browser as the person
who wrote the content.

For more background on this please see my report at
http://www-uk.hpl.hp.com/people/marbut/currTechDevInd.htm. I also recently
put together some additional material for the device independence working
group based on some comments I received from Graham Klyne. They may also be
useful to folks here so they should be available from my web page from
tomorrow  http://www-uk.hpl.hp.com/people/marbut/currTechExtra.htm
regards
Mark H. Butler
Hewlett Packard Laboratories Bristol

Received on Friday, 22 June 2001 06:04:10 UTC