[comp.os.mach] Which is better, process-based OS or object-based OS?

malcolm@oahu.cs.ucla.edu (Malcolm Lui) (03/15/90)

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?

Could you also please explain why?

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'm sure that processer-based OS have their advantages, but I
am not familiar enough with them.

Do you have any opinion on either type of OS?

Thanks for your time and ideas.

Malcolm Lui

E-mail: malcolm@CS.UCLA.EDU  or  ...!{trwspp,cepu,uclachem}!ucla-cs!malcolm

jnixon@andrew.ATL.GE.COM (John F Nixon) (03/15/90)

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

raveling@isi.edu (Paul Raveling) (03/23/90)

In article <33030@shemp.CS.UCLA.EDU>, 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?

	I'm not familiar with Cronus, and am probably out-of-date
	on Mach, but it might be worth putting in 2-bits-worth.
	What I consider the ideal environment is process-oriented,
	but operates in a way that makes it easy to run object-oriented
	applications by mapping each object onto a process.

	The bottom line from our experience with non-UNIX systems
	in the '70's was that Process-Oriented-Programming was a
	big winner, even without formal inheritance mechanisms.
	It's possible that the main challenge in combining process-
	and object-oriented approaches is to reap the benefits of
	inheritance without letting it get in the way.


----------------
Paul Raveling
Raveling@isi.edu