perm filename DIALNE.MEM[DIA,JMC] blob
sn#304562 filedate 1977-09-08 generic text, type C, neo UTF8
COMMENT ā VALID 00009 PAGES
C REC PAGE DESCRIPTION
C00001 00001
C00003 00002 DIALnet Memo #1
C00004 00003 DIALnet Page 2
C00009 00004 DIALnet Page 3
C00014 00005 DIALnet Page 4
C00018 00006 DIALnet Page 5
C00022 00007 DIALnet Page 6
C00026 00008 DIALnet Page 7
C00030 00009 DIALnet Page 8
C00033 ENDMK
Cā;
DIALnet Memo #1
DIALnet
John McCarthy and Les Earnest
9/8/77
These protocols are being developed as part of the
DIALnet project at the Stanford University Artificial
Intelligence Laboratory supported by NSF grant MCS 77-02080
with John McCarthy as Principal Investigator.
DIALnet Page 2
The DIALnet Concept
DIALnet will be a set of protocols (like those of the
ARPAnet) enabling a computer user at a terminal attached to
his own computer to send messages to users of other
computers, to transmit files between his own and other
computers, and to use other time-shared computers directly -
all using the facilities of the ordinary dial-up telephone
network. His computer will need a telephone dialer and a
suitable modem and must implement the DIALnet protocols in
its operating system.
The Stanford University Artificial Intelligence
Laboratory, with support from the National Science
Foundation starting 1 July 1977, has begun an eighteen month
study which will design and experimentally implement
suitable protocols.
While we expect the main users of DIALnet to be
time-sharing systems, we hope the protocols will be
implementable by single user computer systems,perhaps even
down to the level of hobbyist computers. We call the system
DIALnet by analogy with ARPAnet, but unlike the ARPAnet, it
requires no administrator to "admit" new members; they need
only implement the protocols and know each other's telephone
numbers.
We need and solicit the co-operation of computer users
and manufacturers in developing protocols that will be
suitable for standardization. Mistakes made now may have a
long life.
The ARPAnet connects about a hundred computer
facilities involved in Defense Department supported research
and allows users of one system to log in on others, allows
transmission of messages between users of different
computers, and allows the transfer of files between
computers. More generally, it allows interaction among
programs in different computers.
These facilities have proven valuable in aiding
collaboration among computer scientists at different sites
and in permitting nationwide access to unique facilities
such as the MACSYMA system for computing with algebraic and
analytic expressions at M.I.T. They permit a new form of
publication in which documents are kept in the computer, are
continuously updatable, are immediately accessible
throughout the country, and in which comments from readers
are accessible to other readers.
The usefulness of the ARPAnet has prompted many
non-defense installations to try to connect to it, and in
some cases this has been possible, but usually the
institutional and financial obstacles have been insuperable.
DIALnet Page 3
The main financial obstacles are the need for a dedicated
computer called an IMP costing about $80,000 at each site
and the need for dedicated communication lines rented by the
Department of Defense at great expense from the telephone
companies. Other networks have been started, some for
particular user populations and others on as common
carriers. However, they have higher base and overhead costs
than can be achieved with direct use of the telephone system
and don't presently offer message, file transfer and login
services.
We propose to design protocols that can be implemented
at any time-shared computer installation or single user
computer system without joining any formal network. The
hardware cost will be from $500 to $5000 depending on the
type of system and how difficult it is to connect devices to
the computer. For timesharing systems, a telephone dialer
will be rented from the telephone company so that the system
can initiate calls. For small single-user systems where
economy is paramount, the user can do his own dialing to
initiate a call. There will be programs to transmit signals
and information according to the protocols. Any
installation implementing the protocols will be able to
communicate with any other. The only disadvantage compared
with the ARPAnet will be lower speed.
Like ARPAnet, DIALnet will be most useful to full
time-sharing systems or single user systems that operate 24
hours and have file systems. In such systems, each user has
named disk files that are kept in the system even when he is
absent (and therefore remotely accessible), and new files
can be created by file transfer from other machines and on
receipt of messages. The usefulness of the message
facilities normally requires that users habitually log in
each working day and are most beneficial when users have
individual display terminals in their offices. Further
benefits accrue when reports are normally prepared at
terminals and when secretaries use terminals for letters and
messages. However, many less advanced installations have
found the ARPAnet useful and more and more systems are
acquiring economical full time-sharing capability.
While we expect the first users of DIALnet to be
regular computer users, the corresponding ARPAnet facilities
have been much used by non-programmers. Users of DIALnet
need not know how to program, and we expect increasing use
by non-programmers as terminals become more widespread.
In order to make the picture more concrete, here is a
scenario of the use of the system suitable for scientists.
Other potential users may imagine their own scenarios. The
syntax contained in the scenario is not a proposal; we will
have to think much more before we have such a proposal.
DIALnet Page 4
Scenario
A user named Smith types on his terminal
mail Organik
Do you have any active work there on human red
cell carbonic anhydrase B?
The system looks up Organik in Smith's correspondent
file and discovers that his computer pseudonym is "NAT" at a
computer called UTEX-CHEM1 that is reached at (512) 471-3221
via a 1200/150 baud asychronous modem. It selects an
outgoing line with a matching modem, dials the number and
attempts to transmit the message. If the transmitting
computer cannot elicit a response from the desired
recipient, it informs the user that it will try again later
and send him a message when the transmission has succeeded.
If the user's correspondent file did not contain the
telepone number and modem characteristics, the user would
have to supply them.
The identity and location of the sender and date and
time of the message are automatically placed at the front of
the message. At the receiving end, if the addressee is
logged in on the computer, he is immediately informed that
mail has arrived and from whom. If not logged in, he will
receive the message the next time he logs in. In either
case, he can use the same facility to respond:
mail Smith
David Piranha (DAVE@UTEX-CHEM3) has a student
working on inhibition by anions of anhydrase B.
Following up on this lead, the user types
link dave@utex-chem3
A connection is made to the specified computer and, if
DAVE is logged in, he immediately receives a message saying
** Link request from Smith @SU-CHEM7 **
He could then type "link" and have his keyboard and
display effectively linked to those of the caller,
permitting a conversation.
Let us suppose, however, that DAVE is not logged in and
the caller is so informed. He then types
locate dave@utex-chem3
DIALnet Page 5
which obtains the following information from the specified
computer:
David Piranha last logged out at 23:47 on May 9,
1976. Plan: I will be out of touch May 10
through 16. I plan to visit Martin Shumway at the
University of Utah on May 17 and should return by
May 18. Will check mail from Utah.
Noting that the current date is May 14, so that there
is no point in getting the message there quickly, Smith
types
night mail dave@utex-chem3
I am interested in your work on anhydrase B. If
possible, give pointers to online documentation,
else give me a call at (415) 497-4430 (Stanford)
or (415) 321-7580 (home).
The "night mail" command causes the message
transmission to be deferred until inexpensive nighttime
telephone rates are in force.
Additional capabilities of the DIALnet system can be
used to follow up on the above inquiry, as follows.
The ability to access remote text files will
be provided (with permission of the owners
required, of course). This interactive reading
facility will include the addition of "footnotes"
to various parts of the text. These footnotes may
be declared private (i.e. belonging to the
reader) or public (available to the author and
possibly others).
It will be possible to run programs on a
remote computer, permitting experiments with
programs developed in other places. This facility
will permit the sharing of unique specialized
capabilities over a geographically distributed
population.
File transfers will be permitted, with
suitable error detection and correction features,
to permit sharing of data. The communication
protocol should be able to adapt to a wide range
of noise conditions on phone lines.
DIALnet Page 6
Protocols
In order to make these facilities available, suitable
protocols must be designed, and in the course of this, a
number of technical problems must be solved. Besides the
protocols themselves, which are communication procedures and
data structures, there will be a recommended set of
terminal-level commands with syntax prompting and standard
error messages.
We believe that we have the experience to produce a set
of workable protocols, and that it is better to start with
an implementation than to standardize something that doesn't
exist. The latter procedure in recent years has led to
gold-plating the requirements to the extent that the
standard is not implementable.
We plan to devise suitable protocols, test them at a
few sites, publish them, and attempt to convince other
installations to implement them. Almost certainly, initial
experience will produce a requirement for changes, and
standardization committees will be formed and set to work.
A likely forum for a standardization effort would be through
the ACM to the American National Standards Committee.
We propose to allow interaction with ARPAnet sites via
TIPs and propose to discuss with ARPA and DCA whether this
will be allowed.
The most general use of DIALnet involves a program in
one computer "waking up" and interacting with a program in
another machine. DIALnet protocols will handle human
messages as a subcase of this, taking into account the fact
that the subcase will have the most application for a long
time to come. Messages about where to deliver a message
sent by one time-sharing system to another will be handled
as a special sort of message that one program may send
another in cases where the two programs are not written
together, but each must know a certain "public" language.
Thus we will attempt to make a general format for requests,
questions, and assertions suitable for communication between
computer programs. We will study how to make this mesh with
communication between computer programs and people.
DIALnet Page 7
Research Issues
There are many research issues, and we don't expect to
settle all of them in the time and with the resources
requested in this proposal. Since we expect many of the
issues will be clarified by the initial implementation, we
will concentrate on getting a reasonable first
implementation into experimental use.
Here are some of the issues we will study:
1. What error correction facilities are
required to make up for the deficiencies of
telephone lines?
2. What is the minimal necessary burden on
the time-sharing computers carrying out the
communication? What is the trade-off between
buffer size and compute time?
3. Can dial-up telephone communication rates
meet most of the needs for communication between
computers belonging to different research
organizations?
4. What is the best way to handle the fact
that different modem speeds have different prices?
Should one strive for a standard speed or can a
wide variety be easily accomodated? Is the time
ripe for a micro-processor based modem that can
communicate at any speed up to a maximum and
adjust its speed to the requirements of the line
or the possibly less advanced modem with which it
communicates?
5. How will the improved communication
affect research? Since changes will be slow, how
can we tell as early as possible what the effects
will be?
6. What style of interaction is convenient
for both experienced and inexperienced users? How
can communication programs be made self-teaching
without being cumbersome?
DIALnet Page 8
Research Plan
We plan to undertake this project with rather modest
staffing. Initial emphasis will be on designing and
implementing experimental protocols using existing computer
facilities at Stanford. We will also rely heavily on the
co-operation of other organizations that have expressed
interest in the project both in determining the protocols
and in implementing them for specific machines. Two of the
initial implementations will be at the computer facilities
of the Stanford Artificial Intelligence Laboratory (SAIL)
and the Low Overhead Timesharing System (LOTS), also at
Stanford. The latter is a DECsystem-20 using the TOPS-20
operating system, so the protocols might be available early
to users of such systems. We hope there will be interest in
early experimental implementation on other computers.
In the following six months, we plan to test, evaluate,
and modify the protocols. During the latter part of this
period, we plan to publish the protocols and encourage
additional groups to join the DIALnet community.
Note: This document is adapted from our NSF proposal
and retains some of that eleemosynary flavor.
For further information contact Lester Earnest or John
McCarthy at Stanford Artificial Intelligence Laboratory,
Stanford University, Stanford, Califoria 94305; ARPAnet
addresses: EARNEST @ SU-AI and MCCARTHY @ SU-AI. Protocol
questions should be directed to Mark Crispin at the above
address or at ARPAnet address MRC @ SU-AI.
This document is DIALNE.MEM[DLN,MRC] @SU-AI.