Project Athena ( was Re: Non Destructive Version of rm)

[Brendan Kehoe]

In <12074 at mentor.cc.purdue.edu>, asg at sage.cc.purdue.edu writes:
Henry Mensch wrote:
>}this is not a distributed computing environment.  replacing character
>}terminals with x terminals (did you know that the x window system came
>}from project athena and is an athena network service?) does not make a
>}distributed computing environment.
>}
>Well, then i guess I do not have the correct definition of distributed
>environment. The effect is basically the same though as I see it.

   I'd suggest you ftp pub/usenix/network_services.PS from
  athena-dist.mit.edu and give it a read. (If you don't have
  Postscript, you can do some creative vi or emacs replacments and
  have it in a roughly readable form.) You might have a different
  opinion of what a distributed system is and how Athena's net
  services model really cooks. (This is simply my impression -- I've
  never had any direct contact with them.)

>}->We also have it here at GE where each person who has a workstation
>}->can still log into anny workstation and be able to access his disk without
>}->having to do mounting all over the place. If I want to get to a directory
>}->/tmp on the system a294 I do cd //a294/tmp - no problem.
>}
>}and how do you think //a294/tmp gets there?  magic?  maybe the
>}workstation *gasp* mounts a filesystem there for your use when you
>}make such a request.  maybe they're using an automounter?
>
>May be, but I am still not allowed to decide where to mount file system's
>(that is preordained) and I do not have the root password.

  If you're on a client (and not a critical server), sure, it'd cause
  problems, but it would not be out of the question.

>}->Oh, I like your setup even better now. Give all the users root! 
>}
>}you obviously don't understand that (with single user hosts) any user
>}can become root with little/no effort.  project athena's architecture
>}gets over this by making root (on a workstation) a commodity of
>}limited value.  our users don't get root privileges on servers (where
>}data are kept and network services originate from).
>
>This is not neccessarily true. Please explain to me why it is 
>impossible to keep a single user system secure. in any event, 
>using Xterminals with some centralized system, it IS possible
>to keep people from becoming root.

   Oh? And what's to stop someone from hacking into the centralized
  server and completely crippling *ALL* computing ability on your
  entire network? I can imagine some of the people on that Sequent
  that had Xterms hanging off of it would be mighty perturbed.
   While I can't say that the Athena method of distributing the server
  responsibilities among a bunch of machines is far better than others
  (I haven't the experience with both setups to make such a
  statement), I can say that simple logic shows how it works. (And a
  little reading about distributed systems in general helps, too.)

>}bruce, you might do well to have a chat with the manager of UNIX
>}systems at the computing center ... i know he has some clues about
>
>Here we go again. Did you learn that tactic from Jon? Just because
>I disagree with you does not mean I am incapable of understanding.
>I know full well the merits of Athena's setup.

  If you did, then you wouldn't be making such erratic hits at it.

>1) If I am using Xwindows, and I do something CPU-intensive, I cannot
>  even get my pointer to move around at times, much less iconify
>move or size windows. With Xterminals, since the graphics are handled
>by the terminals processor, the function of your windowing environment
>is (somewhat) independant of the load on the man system.

  'Scuse me? How would running a CPU-intensive thing on an Athena
  client effect overall service?

>2) Athena's setup does not take advantage of unused resources when
> only a few people are logged in. My machine is just as slow when
>I do a CPU intensive job whether all 1000 workstations are in
>use, or if only 100 are in use. With the method that I advocate however,
>My job can take advantage of those unused resources. 

  Somehow I doubt that the system stays at precisely the same load
  when usage grows exponentially.

-- 
     Brendan Kehoe - Widener Sun Network Manager - brendan at cs.widener.edu
  Widener University in Chester, PA                A Bloody Sun-Dec War Zone
      "Does this person look relaxed to you?  Well, it's actually an
              experiment of Contour's new 565-E chair!"