Re: Formatting Objects considered harmful

Subject: Re: Formatting Objects considered harmful
From: Alex Milowski <milowski@xxxxxxxx>
Date: Tue, 27 Apr 1999 09:49:55 -0700 (PDT)

On Tue, 27 Apr 1999, [iso-8859-1] Håkon Wium Lie wrote:

> James Clark wrote:


>  > but it's
>  > no basis for the claim that XSL Formatting Objects are harmful.
> If servers output XFO instead of (X)HTML (or other globally known,
> abstract formats) harm is done.

It would make absolutely no sense to do this.  The formatting object are
a collection of instructions to a formatter and provide no real value
when they are realized as an XML document because:

   1.  It is not a linear interpretation of the formatted result (see
       flows, regions, and flow maps).

   2.  They are just instructions that have to be formatted into areas
       and placed in a region.

In XSL there is a concept of a flow and flow map.  Hence, it is possible
to specify as siblings in an "FO document" that is placed in
two different regions on a page.  

Given this, realizing a document as an FO document would provide little
value to a client browser because the browser would still have to do the
layout and placement of areas within the regions and also deal with the
non-linear aspects of the flows.  If a browser could do all this, then
applying the tree construction portion of XSL should be trivial.

IMHO, the sane way to view this is:

   1. XSL on the server that produces a dead format--from XHTML with
      CSS to PDF ("dead" meaning less semantically rich with no ties to
      the original structured content).

   2. XSL on the client with browsers that actually format documents--not
      just XML-to-XML transformations.

Now, don't read this the wrong way.  Browsers do some kind of formatting
today with HTML and CSS.  XSL just goes beyond this in the specification
of format and layout.

Given the above, I don't think we should worry too much about people
shipping FO documents around.  It really isn't practical.

R. Alexander Milowski                                         alex@xxxxxxxxxxxx
               Remember: Stressed spelled backwards is desserts.

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