Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!world!bzs
From: bzs@world.std.com (Barry Shein)
Newsgroups: comp.society.futures
Subject: Musings on the future of computing... (REPOST)
Message-ID: <1991Feb6.165031.14655@world.std.com>
Date: 6 Feb 91 16:50:31 GMT
Organization: The World
Lines: 94

[This seems to have not made it out to USENET so I am reposting -bzs]


Two competing models of computing are currently polarizing development
directions in this field. One is characterized by large, centralized
servers with minimal power directly on the desktop (the "X-terminal"
model.) The other is characterized by the "killer micros" wherein
everyone has roughly equivalent and competent compute power on the
desk.

Each model has its proponents and its rationales.

At one extreme are projects such as Plan 9 at Bell Labs which utilizes
essentially X-terminals (although they don't run X, but devices
capable of running little else but a window system) and a system of
servers (compute, file, etc.)

The rationales for such an approach are:

	A) People should not (and do not want to) waste their
	time administering the system on their desktop. Powerful,
	self-reliant desktop systems are complicated and require
	constant care and attention. Efforts to eliminate or simplify
	this administration are futile. Mere software version updates
	can be a nightmare.

	B) Most cycles within an organization (and hence, most of
	the cost) is wasted if power is put onto the desktop. The
	assumption here is that one can generally not utilize the
	idle power on someone else's system as effectively as they
	could a centralized server with the sum of many machines'
	power available in one large system.

	C) The complicated hardware spread across desktops is
	expensive and difficult to maintain.

	D) There are economies of scale available in centralized
	systems, such as large, centralized information repositories
	(eg. phone books, maps, textual materials etc.)

The other extreme is typified by the high-end workstation enviroment,
providing near-mainframe CPU performance and hundreds if not thousands
of MB of disk on every desk top.

The rationales for this approach are:

	A) Predictability of response, one is not captive to
	the whims of other users who might find a way to make
	life on a shared system miserable by constantly running
	large jobs.

	B) Distribution of political control: Centralized resources
	tend to build centralized control with all its political
	foibles. Usage becomes subject to least common denominator
	rules if resources become scarce in any way and these rules
	rarely take into account the actual nature of the job at
	hand being attempted by the individual user. Worse, centralized
	systems tend to breed a certain amount of pettiness and paranoia
	where real or imagined infractions are punished by denial of
	access in an attempt to maintain respect for "the rules".
	Yet worse, influential but corrupt or misguided administrators
	can easily make one's life hell by manipulating centralized
	resource allocations.

	C) Purchasing decisions become centralized and often
	devolve into reflecting ease of maintenance and administration
	rather than work goals. For example, hooking image scanners
	to centralized systems is often very cumbersome and tends
	to be avoided whereas hooking the same devices to desktop
	systems is almost trivial and any inconveniences (e.g. if
	the scanner causes the system to hang or crash occasionally)
	are borne by the owner of the system and not subject to
	group consensus.

	D) If the centralized system is unavailable then many
	people would be idled. In a more distributed system then
	fewer people are idled due to a machine becoming unavailable,
	often just the person who's machine has died.

One observation is that centralized systems tend to be information
oriented while decentralized systems tend to be compute oriented.

If the goal is to provide wide access to large bodies of information
then the centralized scheme tends to be attractive. If the goal is to
provide everyone with access to reliable amounts of computing power,
then decentralized schemest tend to be preferred.

Thoughts and expansion appreciated.

-- 
        -Barry Shein

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