Re: Another suggestion & a question for Eric Miller (Was RDF Display Vocabulary Second Draft)

From: Stefano Mazzocchi <>
Date: Wed, 13 Oct 2004 15:09:58 -0400

David Huynh wrote:

> David R. Karger wrote:
>> I'm not certain the distinction between "view" and "lens" can really
>> be formalized---obviously, every view is only showing some aspect of
>> the object. But there do seem to be very different ends to the
>> spectrum, that perhaps need to be handled differently?
> In practice, when one writes a lens in Haystack, it is often with hopes
> that the lens can be used for more than one type of information (e.g.,
> an "address" lens can be used for people and companies). When writing a
> view, it is often with concession that it can only be used for one type
> of information, in a limited context, for a particular task. The view is
> specially laid out and cannot be guaranteed to generalize.

Right on! I like the idea of separating between a view and a lens based
on its rate of generalization.

On the other hand, I can't stop thinking that this "degree of
generalization" is really a float and not a boolean.

> When we created the view architecture, we conceded that we did not know
> how to separate content (e.g., set of property-value pairs to show) from
> presentation. Then we created the lens subsystem and tried to ignore
> presentation altogether (i.e., we laid those pairs in a table,
> regardless of whether there were more effective layouts). That is, a
> lens is a selection of content to be shown, while a view is both a
> selection of content and a (specialized) layout of that content.

I think we are converging on the idea that there are at least two layers
for content:

  [selection] ---> [presentation]

and the scope of this effort is to trying to minimize the ontology so
that it works in the [presentation] layer.

Note that there are three aspects that we still haven't considered:

  - adaptation: the act of adapting the content to some given needs
  - interaction: the act of capturing user events and translate them
into further selection or adaptation
  - modification: the act of modifying the content in a persistent way

I was talking to David yesterday and we agreed that while we should try
to modularize the ontologies as much as possible, it's also pretty hard
to draw a line without knowing where the other things on the table would
go when needed.

What do you people think about that?

Stefano Mazzocchi
Research Scientist                 Digital Libraries Research Group
Massachusetts Institute of Technology            location: E25-131C
77 Massachusetts Ave                   telephone: +1 (617) 253-1096
Cambridge, MA  02139-4307              email: stefanom at mit . edu
Received on Wed Oct 13 2004 - 19:09:59 EDT

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