Re: A Model of System Structure and Program Behavior

[Marcus Brinkmann]

At Thu, 12 Jul 2007 17:50:24 +0200,
Neal H. Walfield wrote:
> 
> System Structure
> ----------------
> 
> A general-purpose system consists of a number of computational
> activities (hereafter referred to simply as activities).  Typically,
> an activity has a single purpose: the delivery of some result to the
> activity that initiated it.  An activity may consist of multiple
                                  ^^^^^^^^

a program?

> activities.  These are typically loosely coupled.  That is, there are
> few interactions between the sub-activities.  This provides the view
> of a system as a nested hierarchy of activities.
> 
> This nesting of activities can be observed by considering a typical
> desktop scenario.  A user's shell is an activity that acts on behalf
> of the user and is the ultimate parent of all activities that run on
> the user's behalf.  A user may have a number of programs running on
> her behalf.  For instance, a web browser, an editor, an email client,
> an audio player, etc.  These programs are very loosely coupled at
> most.

I would agree, but want to point out that this loose coupling has been
source of considerable amount of frustration, and some people seem to
push towards more integration, not less.

Mmh, just to pick some random examples: GNOME.  The browser as a
platform.  More experimentally, the haystack project
(http://haystack.lcs.mit.edu/).

> Program Behavior
> ----------------

nice section

Marcus