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Network Working Group A. Bhushan
Request for Comments: 578 N. Ryan
NIC: 19501 MIT-PTD (DMS)
October 1973
USING MIT-MATHLAB MACSYMA FROM MIT-DMS MUDDLE
An Experiment in Automated Resource Sharing
I. INTRODUCTION
This paper describes an experiment in non-trivial automated resource
sharing between dissimilar systems. The goal of the experiment was
to interface the MUDDLE system at MIT-DMS (Host 70.) to the MACSYMA
system at MIT-Mathlab (Host 198.), in such a manner that the MUDDLE-
user at MIT-DMS is not required to know anything about the ARPANET,
Mathlab, or even MACSYMA. In fact, the user need not be aware that
part of the computation is performed by MACSYMA on the Mathlab
computer.
This experiment differs from the MATHLAB-UCSB/OLS experiment (ref.
NWG/RFC 525, NIC 17161 "MIT-MATHLAB Meets UCSB-OLS" by Parrish and
Pickens) in several important respects. First, the use of the remote
network resource is *completely automated*. The human user does
nothing more than use a function in MUDDLE such as "INTEGRATE" which
requires the remote MACSYMA resource for computation. The program
performs all the required tasks of connecting to Mathlab, log in, and
using MACSYMA. (In the UCSB-OLS experiment, the user had to manually
connect to Mathlab, login, use MACSYMA, type the input in a form
suitable for MACSYMA, save the results in a file at Mathlab,
disconnect from Mathlab, start a retrieval job at UCSB to retrieve
the "saved" results, and finally submit the results to a local
program.) Second, the use of the remote resource is *completely
integrated* into the local MUDDLE system. The user can specify the
computations in a form that MUDDLE understands. The resource-sharing
program (whose existence the user need not be aware of) does the
translation from the MUDDLE "prefix" form to the MACSYMA "infix" form
on input, and vice-versa on output. This ability allows the MACSYMA
resources to be completely integrated into MUDDLE to the extent that
parts of the same computation can be performed by MACSYMA and others
by MUDDLE.
II. THE MACSYMA AND MUDDLE RESOURCES
Before proceeding to describe the resource sharing facility a
description of the two resources, MACSYMA and MUDDLE, is in order.
The MACSYMA system at Mathlab is a powerful resource for symbolic
manipulation of algebraic functions. It can, among other things,
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RFC 578 Using MIT-MATHLAB MACSYMA from MIT-DMS MUDDLE October 1973
perform symbolic integration and differentiation, expand series,
perform Laplace and inverse-Laplace transforms, solve equations and
systems of equations, and simplify rational functions. (A
description of MACSYMA's capabilities is given in "The MACSYMA Users'
Manual" available from the MIT-Mathlab group at Project MAC.)
The MUDDLE system provides a general-purpose environment suitable for
automatic programming, graphics, data management, "networking", and
mathematical computations. The MUDDLE language represents a powerful
extension of the list processing language LISP in the area of data
types such as strings, vectors, uniform vectors, and user definable
types. (MUDDLE is described in some detail in "The MUDDLE Primer"
(SYS.11.01) by Greg Pfister, available from the Programming
Technology Division at Project MAC.)
MUDDLE has extensive graphical and numerical computation facilities.
The user can display graphs on ARDS and IMLAC type consoles, and on
the Evans and Sutherland (E&S) display system. The MUDDLE console
graphics provide a facility to view graphical representation of
functions with overlay capability and automatic scaling that can be
controlled by the user. The E&S provides the user with a versatile
tool for studying the dynamic characteristics of graphs, curved
surfaces, and other three-dimensional objects. The combination of
MACSYMA, MUDDLE, and the E&S graphics capabilities represents a very
powerful resource for problem solving that is integrated and made
easily usable by the resource sharing facility.
III. THE AUTOMATED RESOURCE-SHARING FACILITY
The resource-sharing facility described herein uses the most easily
accessible communication path to MACSYMA, the TELNET connection to
the logger service on socket 1. No modifications were made to
MACSYMA, nor were any special programs created on the Mathlab
computer. The entire task of resource sharing is performed by
programs in MUDDLE. Let us say on the outset that we are not
advocating this mode of usage for automated resource sharing. A
resource-sharing protocol that allows convenient use of remote
resources via programs is a far more reliable and efficient way, but
that requires work on the part of server sites. The existing
protocols and systems FTP, RJE, RSEXEC, and the Datacomputer cater to
a limited subset of easily managed resources. We register here our
desire for uniformity (which alas is lacking) in the current systems,
and work along the direction of general-purpose resource sharing. In
the absence of a general resource-sharing protocol and a MACSYMA
server to go along with it at Mathlab, the TELNET connection is the
best a user can do.
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RFC 578 Using MIT-MATHLAB MACSYMA from MIT-DMS MUDDLE October 1973
The resource sharing facility comprises of several independent but
integrated parts. These are:
1) Connecting to Mathlab, login, and invoking MACSYMA.
2) Conversion of MUDDLE's prefix to MACSYMA's infix form.
3) Generation of MACSYMA input.
4) Interpreting MACSYMA's results including errors and comments.
5) MACSYMA infix to MUDDLE prefix conversion.
6) Plotting graphs for the functions.
7) Allowing human intervention if desired.
8) Disconnect from MACSYMA.
The user (assuming that he has loaded the necessary programs in
MUDDLE) to integrate the function "3*X" has only to type:
<INTEGRATE '<* .X 3>>$
where '