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From: jnixon@andrew.ATL.GE.COM (John F Nixon)
Newsgroups: comp.os.mach,comp.os.v
Subject: Re: Which is better, process-based OS or object-based OS?
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Date: 15 Mar 90 13:59:07 GMT
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malcolm@oahu.cs.ucla.edu (Malcolm Lui) writes:
>In your opinion, which type of operating system do you think is
>better, process-based OS such as Mach, or object-based OS such as
>Cronus?

In my opinion, Cronus isn't an Operating System.  Cronus simply
provides some abstractions across a network of computers; it cannot
run without the assistance of some underlying OS.  Cronus/Posix would
be such a combination, but then Cronus/Posix isn't object based.

I would also argue that Mach is object based in some sense.  Mach has
task objects with threads running inside, so you really do not have an
indivisible "process" in Mach.  Unix (any flavor) would be an example
of a process based OS.

>I feel that object-based OS may have the edge due to:
>		 - Capabilities for control of object access and modification
>		 - Encapsulation that allows for easy design of objects.
>		 - Nested objects

I cannot yet speak from long experience, but I like both Mach and
Alpha (Alpha is another example of an object based OS, and has more of
an object flavor to it than Mach).  The natural way that capabilities
fall out of object based OSes is nice.  The fact that the OS ensures
object separation can be a property of either a process or an object
based OS; you just think of a process based OS as having only one
"thread" per object (process).  I haven't yet seen an OS that allows
nested objects (I *think* Smalltalk allows this, but I am not familiar
with Smalltalk).

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jnixon@atl.ge.com                    ...steinmetz!atl.decnet!jnxion