macfs@levels.sait.edu.au (10/11/90)
I'm thinking of using ISIS for the practical work in teaching an Honours (4th year) distributed computing subject (one semester) next year. I'd be interested in any feedback from readers of this group as to the feasibility of doing this, and/or experiences from people that have used ISIS for teaching. Also any comments as to the required hardware configuration. Right now the only applicable hardware is a Sun 4/490. We also have some VAXes running VMS - I gather there's a VMS port on the way. I can probably also wangle access to one or two Sun 3/60's, and it may be possible to get either a Sparcstation or a Mac running AUX. So the worst case scenario is that only the Sun 4/490 could run ISIS, in which case there is no true distributed processing going on, which is hardly the way for students to get a feeling for the subject. (We also have lots of PC's running MSDOS and Macs running MacOS, but that's probably irrelevant). Thanks in advance, Chris Steketee, School of Maths and Computer Studies, S.A. Institute of Technology, The Levels SA 5095 Australia email: macfs@levels.sait.oz.au
ken@gvax.cs.cornell.edu (Ken Birman) (10/15/90)
In article <15516.27149de8@levels.sait.edu.au> macfs@levels.sait.edu.au writes: >I'm thinking of using ISIS for the practical work in teaching.... >....the worst case scenario is that only [a single] Sun 4/490 could >run ISIS, in which case there is no true distributed processing going on... My group has heard from at least five or six departments about ISIS-based courses. My own experience doing this has been quite good, provided that you don't change the system during the semester (around here, this happens quite often). Also, I usually ask people to implement some of the non-ISIS protocols or system interfaces (i.e. Byzantine agreement, Linda tuple space, etc) using ISIS as a communication environment only, so that they get some experience with alternatives to the ISIS style of programming. Regarding the single machine issue, this is not necessarily such a restriction. First, little ISIS code distinguishes the location of processes on a per-machine basis. So, your students will write exactly the same program whether they plan to run three copies on one machine or one copy on each of three machines. Also, ISIS is capable of simulating a multi-site configuration on a single machine. You use a slightly changed "sites file" format, in which the machine name is qualified by a number, i.e. 1: 2000,2001,2002 iserver.sait.edu.au/1 au 2: 3000,3001,3002 iserver.sait.edu.au/2 au 3: 4000,4001,4002 iserver.sait.edu.au/3 au notice that the port-numbers are not repeated and that each machine has a "private" name, if you count the /xxx part. You will get a warning about possible problems with "isis remote" when you start the system, but can ignore this. (However, don't use isis_remote in this configuration!). The above mechanism was broken for V2.0 but is fixed in the general ISIS V2.1 release. Ken