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From: davidh@dent.Berkeley.EDU (David S. Harrison)
Newsgroups: comp.sys.misc
Subject: Re: What is UNIX? Re: Is SUN a "PURE PLAYER" in window systems - SunView or OpenWindows??
Message-ID: <20997@pasteur.Berkeley.EDU>
Date: 4 Jan 90 19:58:25 GMT
References: <.3ZB2Cxds13@ficc.uu.net> <9001021449.AA21356@super.super.org>
Sender: news@pasteur.Berkeley.EDU
Reply-To: davidh@dent.Berkeley.EDU (David S. Harrison)
Lines: 37

In article <.3ZB2Cxds13@ficc.uu.net>, peter@ficc.uu.net (Peter da Silva)
writes:
> The first rule of system design is: make the easy things easy, then make
> the hard things possible. This is best done by providing a simple unifying
> concept that defines the system. I've not heard a lot about Apollo
Domain, but
> what I have heard is typical of pre-UNIX proprietary systems: lots of
> complex system calls and data structures, I/O tied closely to the hardware.
> And X is certainly complex to use.
> 
> Am I wrong? What's the simple unifying concept for DomainOS? Or X?

Personally, I don't see a simple unifying concept in NeWS either.
Basically, window systems are complex because they are asked to
provide a wider range of functionality than most systems.

I am also not convinced of your rule of system design.  Complex tasks
are most often successfully tamed using a layered approach.  I like
to think of networking protocols as a good example.  TCP/IP is built
on a number of protocol layers each providing a higher level of
abstraction.  Building TCP/IP from scratch is quite difficult and
error prone.  Good layered systems tend to use the concept of
mechanism vs. policy.  The low-level framework of your system
should be designed so that *all things are possible* (mechanism)
and higher levels should use this lower level to provide convenient,
application dependent access to your system (policy).  This way, if
someone wants functionality that is not present at higher levels,
they can use lower levels to implement it.  I claim both X and NeWS
are the low-level framework of a user-interface system.  As such,
I think X is the better design because it allows greater freedom
(through lower-level access) to design high-level toolkits. I won't 
belabor the point since much of this discussion is highly religious
and I doubt anyone is about to change their convictions.

			David Harrison
			UC Berkeley Electronics Research Lab
			(davidh@ic.Berkeley.EDU, ...!ucbvax!ucbcad!davidh)