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From: brian@babbage.csus.edu (Brian Witt)
Newsgroups: comp.lang.eiffel
Subject: Re: Inter-Process Communication
Summary: on a hypercube/1
Keywords: parallel processing, IPC
Message-ID: <1990Jun10.210541.2656@csusac.csus.edu>
Date: 10 Jun 90 21:05:41 GMT
References: <230@rossignol.Princeton.EDU>
Organization: California State University, Sacramento
Lines: 43

In article <230@rossignol.Princeton.EDU> cwc@cs.Princeton.EDU (Chris Clifton) writes:
>Has anyone written any sort of inter-process communication
>primitives in Eiffel?  Preferably something based on UNIX
>sockets (I'd also like inter-processor communication eventually.)
>I'd be interested in hearing experiences and getting suggestions,
>even if you aren't in a position to share actual code.

For a class project, a friend and I created
several classes to provide inter-nodal communications on
an Intel HyperCube/1.  Since the HyperCube/1 is 16-bit and Eiffel is 32-bit,
we ran the code on a simulator.  We created two class pairs; one a high level
interface, and another a low level interface.  The high level provided
functions like send-message and get-message.  Basic nodal routing was
provided.  These routines called methods in the low-level portion
that actually got the work done.  The goal here was to create something
that was independent of the OS functions.

The other class pair concerned messages.  Our messages were like
postal envelopes: they contained some data, and routing instructions.
There was an input buffer and an output buffer.
The user's application had to copy out of these buffers to use the
data, since doing  ringleft.receive  overwrote the contents of the
buffer.

Our goal of OS independent messaging on arbitrary parallel processing
topologies was easily acheived.  Tony (my partner who wrote these
interface routines) said Eiffel ensured he wrote correct code, and
the system worked stright out.  The pre- and post-conditions helped
out tremendously.  Multiple inheritance allowed us to create message
classes that could message (from one class), and also know about
a topology (another class).

We also created a feature that allowed us to peek into the actual
storage of an ARRAY object.  It's very nasty, and I won't force
it on anyone -- mail if you'd like a copy.  maybe I'll post it
if I feel brace enough.  It is _very_ nasty.


>Thanks-
>-Chris Clifton (cwc@Princeton.EDU)

--- brian (now with better objects) witt
brian@babbage.ecs.csus.edu   -or-  seer.UUCP!rael!aleks