Re: Fresnel: Styles: summary and unsolved issues

From: Jacco van Ossenbruggen <>
Date: Mon, 25 Apr 2005 16:55:09 +0200

Emmanuel Pietriga wrote:

> Me: I see your point. But that seems to be were we diverge. I do not
> consider the CSS/SVG/whatever part of Fresnel styles to play a central
> role. That is not the most interesting part of Fresnel styles. In my
> opinion, Fresnel is not about defining how to layout data, or even how
> to *precisely* style it with instructions such as:
> "display:table-cell;padding-top:1em;border-bottom: 1px solid black".
> For me, Fresnel is about encoding display *knowledge*, not precise
> instructions. We are not inventing a new styling/layout language such as
> CSS, or even adapting it to RDF.

This is good to hear, but it is not the impression I got from reading
the paper and the manual document.
Maybe you should emphasize this more in the paper. For example, by
using the external CSS stylesheet with
the fresnel:styleClass as the main example instead of the current
fresnel:valueStyle and propertyStyle.
The latter could just be mentioned in the text. Maybe the role of the
box model should also be de-emphasized.

But most important, you should state very carefully what part of the
styling is the core of fresnel, and what is left for the application.
Again, the description of the box model and detailed CSS style property
specification in the example gave me the impression you are aiming for a
"complete" style solution that leaves very little or nothing to style
for the application.

> I am more interested in more abstract
> parts of fresnel styles, such as fresnel:contentBefore, fresnel:label,
> fresnel:value, etc., i.e. the part of Fresnel styles that are RDF
> specific. This is what counts for me, and this part *is* portable across
> representation paradigms. I find it to be useful. At least that is what
> I think.

I agree. And even in Stefano's lens-only model, you would need the
label part because once you are in XML-tree world you don't want to (or
cannot) query the RDF for the labels anymore. This is exactly what
happens in Noadster, where we query for the labels in the
RDF-graph-to-XML-tree phase, so that the CSS/XSLT styling phase can
freely choose to use or ignore the labels.

> Besides, I do not reject Stefano's proposal of an intermediate tree as
> the result of the selection process. I don't think this format has
> been clearly defined and I'd like to hear more about it. However I do
> have an question about what I've heard: this <div>-based tree
> structure just looks already too Longwell/CSS-oriented to me. Stefano,
> you've been arguing that Fresnel should not define an implicit layout
> method. I entirely agre with you. But doesn't this tree structure
> already goes down this path? I'm not saying it does; it is just the
> impression I get from it.

Maybe <div> has just too much HTML/CSS layout associations, what about
<g> (a la SVG)?
For me, and I assume Stefano agrees (lets hear it if he's not), the key
idea is that a lens can output an ordered tree. Graph-based tools may
choose to ignore the tree and just build a graph as theyt would from a
flattended output structure (but I can easily envision a graph tool that
uses the tree structure to allow folding and unfolding of subgraphs!).
But other tools may use the tree structure for building sections and
subsections etc in a document model or CSS-like box model.

Received on Mon Apr 25 2005 - 14:54:22 EDT

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