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proposals for meta-applications, frameworks, windows...(long message)

    Date: Tue, 14 Jul 1992 17:17+0200
    From: Scott McKay <SWM@stony-brook.scrc.symbolics.com>

    No deep thought has been spent in this area.  Nobody with a vested
    interest has submitted any proposal in this area, never mind a coherent
    proposal.  As usual, concrete proposals are welcome.

I haven't though deeply either, however, I think CLIM has a concept of
applications (at least a word for the concept, cf
define-APPLICATION-framework...).

I think it's adequate. But...

1- proposal for a meta-application
----------------------------------
For multiple instanciations of applications (select-c-?), there should
be a "higher thing" if there is a need to control all the applications.
I can imagine several applications using common information - something
like a central database.  The specific application information can be
stored in state variables (things like "preferred view" for visual
representations,...) and that's good.  But for the moment, the only way
to share between applications is by using global variables, which is too
"high level", I think.

The "higher thing" could be named something like a meta-application, or
an application-manager,...

It should have state variables of its own and, at least, a list of
applications that it "manages".


2- proposal for DAs
-------------------

CLIM also has concepts of frameworks, panes and windows.  I must
admit that I've long been mixed up with these and I'm not sure I can put
all the pieces in the correct places yet.

First it seems to me that clim-windows are not the same as
things-usually-called-windows (in X, Mac, ...).  If I am correct, these
systems all talk about a root window (one per screen??) that has
child windows (for the mac, the root window could be the desktop).

I think that the questions of applications and visible objects have to be
separated.

So what we need could be (this is my first try):

Preliminary:
Since everybody uses the same words in various senses, I'll try to use
words that mean nothing (don't say I always do!).  This way, the
confusion will be lessened and words will be found later for these
entities.  I'll talk about DAs (for display areas).  They need not be
real DAs, they could be virtual and/or infinite (as with clim's drawing
panes).

   a level0-DA: the ancestor of all level1 DAs (has pointers to
                       them)
   a level1-DA: the most general area where display can occur (it can
	be shared by various machines - useful for future very heavy
	applications that use multiple machines to cooperate in the
	display of something).  In the X world, all the
	network-distributed windows could be part of the same level1-DA.
	This could also be called something like "virtual distributed
	desktop".

   a level2-DA: the total area a single machine can access
	locally (the generalized desktop, maybe displayed on more than
	one screen - cf a mac with several screens) 

   a level3-DA: this could correspond to the area displayed by a unique
	screen on one single machine.  This is the first DA not to be
	virtual (or could there be virtual screens?).
	
   a level4-DA: could be a single visible object (a window in most
        window systems, but also a framework in clim's terms if my
	understanding is correct).

   a level5-DA: a subdivision of level4-DA (panes for clim).

   etc...


Now I'm asking the specialists: will there be a mapping from all other
systems' concepts (X-root window, X-window, mac desktop, mac window,
clim's frame, panes, views, viewports, menus, dialogs, sheets,...) to
these????

>From there, one could see where the connection between applications
(processes,...) and DA is best done.  Does an app manage leveli-DA?
etc...

These are my first thoughts...  Please comment on these.

vk
===============================================================
Keunen Vincent                  Network Research Belgium
R&D, Software Engineer          Parc Industriel des Hauts-Sarts
keunen@nrb.be                   2e Avenue, 65
tel: +32 41 407282              B-4040 Herstal
fax: +32 41 481170              BELGIUM
===============================================================
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