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

From: David R. Karger <karger_at_mit.edu>
Date: Mon, 18 Oct 2004 00:28:48 -0400

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   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.

True, but we achieve some generality by writing views for superclasses
of common types. For example, one can craft a "message view" that is
simultaneously appropriate for emails, IMs, and RSS postings.

   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.
Received on Mon Oct 18 2004 - 04:28:47 EDT