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Re: XML Conformance Levels [Was: ERB Decisions of March 26th]



> The point here is that I would rely totally on a Java based solution at the 
> bottom layer.  It isn't possible to ask people to install a (platform-dependent)
> scheme compiler, Jade engine, etc.  This is 
> because I want my applications to work in a Java environment.  Maybe perverse,
> but I cannot expect my colleagues to download Jade and learn even simple DSSSL.
> Java is more distributable.

Sounds quite reasonable to me!  :-)

> > 
> > > 	- our community will take years to write in it.
> > 
> > I don't understand.  Are you saying it will take *years* to write stylesheets?
> 
> Probably.  Stylesheets are seen as publishers' tools or beautifiers for 
> display.  They are not seen as things which transform documents in a 
> discipline-relevant manner.  

Transformation are part of DSSSL as well.  ...but they are a different part of
the standard.  What does "discipline-relevant" mean?

> > 
> > > 	- they think that plugins and CSS will solve their problems anyway
> > 
> > Some, maybe, but it doesn't scale.  I'm both excite and disappointed 
> > about CSS.
> 
> This is only a small number anyway.  Most of them will probably not have 
> encountered stylesheets or will use them for simple font manipulation.
> [BTW I don't want to seem arrogant.  The problem is that documents are not
> seen as exciting, but data are.  Therefore people still write one-off programs
> to hack data.]  So the typical activities are EITHER:
> 	- download some html, and display it
> OR
> 	- download some data and crunch it.
> 
> If the html 'contains data' download it as a legacy file and write a one-off
> plugin to tweak it a bit.

The 'data crunching' seems to be what the transformation side of DSSSL is for.
Right now, I don't think there is sufficient momentum to get transformations
into XML.  I'd like to see that happen some day...

> > 
> > Note: Any CSS people can correct me if I'm completely off my rocker.
> > 
> > > 	- it offers no functionality *after* parsing (or at least after
> > > 		rendering) as far as I can see.
> > 
> > What do you mean?  After parsing?
> 
> This may be my ignorance (and the WG is not the place to work it out) but 
> I get the impression that stylesheets are primarily for transforming documents
> and formatting them, and not for adding behaviour.  For example, a lot of 
> our methods involve mouseUp(), etc. routines or discipline-dependent 
> processing.

No.  This is a common misconception about DSSSL.  The result of applying a
DSSSL stylesheet is a flowobject tree (or event stream as in Jade--an 
equivalent construct).   A flowobject is a "thing" that has properties.  Thus,
if your application flowobject has a "mouse-up" property, you can specify
what to do with that property.  

In DSSSL you need to separate the description of the data of the behavior
(e.g. what value my "mouse-up" property has) from the use of that
data (e.g. on a mouse up, take the image specified in the property value and
display it).  Formatting is just one kind of style semantic.  Browser
display semantics is another--and this is what you seem to be interested in. 

Once the flowobject has be built, something needs to supply semantics for
making it *do something*.  In jade, this is what the backends are for.  In
my DSSSL environment, that is what an exterior or interior does.

For an example from HTML, in DSSSL I could say:

;; a quick example (not complete)
(element A
   (let ((name (attribute-string "NAME" (current-node))))
      ;; check to see if the name has been specified
      (if name
         ;; make an anchor for a fragment
         (make html-anchor 
               name: name
            ;; other properties)
         ;; make a link to an HREF
         (make html-link
               target: (attribute-string "HREF" (current-node))
               mouse-over: (attribute-string "ONMOUSEOVER" (current-node))
               ;; other properties here)
         )))

This would be a way to transfer the data of an HTML anchor element to one
of two custom flowobject.  Now, there is a "link" flowobject in DSSSL, but this
certainly doesn't have a mouse-up property.

Note: There are many ways of doing the above.

==============================================================================
R. Alexander Milowski     http://www.copsol.com/   alex@copsol.com
Copernican Solutions Incorporated                  (612) 379 - 3608


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