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C00015 00004	.s Scenario
C00025 00005	.s Protocols
C00029 00006	.s Research Issues
C00032 00007	.s Research Plan
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.if faire then start
.every heading(,|%7DIALNET and Home Computers↓←%1John McCarthy and Les Earnest↓
.←%2Stanford University|);
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.s The Dialnet Concept
%2Dialnet%1 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 %2Dialnet%1 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 %2Dialnet%1 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 %2Dialnet%1 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.
.every heading(%3Dialnet,,{PAGE!});

	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.  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, %2Dialnet%1 will be most useful to %2full
time-sharing systems%1 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 %2Dialnet%1 to be
regular computer users, the corresponding ARPAnet facilities have
been much used by non-programmers.  Users of %2Dialnet%1 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.
.s Scenario

.macro bc	⊂ begin group preface 0;nojust; select 4; indent 2,2;	⊃;
.macro econt	⊂ end continue ⊃

A user named Smith types on his terminal
.bc
mail Organik
.break
Do you have any active work there on human red cell carbonic
anhydrase B?
.end

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:
.bc
mail Smith

David Piranha (DAVE@UTEX-CHEM3) has a student working on inhibition
by anions of anhydrase B.
.end

Following up on this lead, the user types
.bc
link dave@utex-chem3
.end

A connection is made to the specified computer and, if DAVE is logged in,
he immediately receives a message saying
.bc
** Link request from Smith @SUα-CHEM7 **
.end continue
He could then type "%4link%*" 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
.bc
locate dave@utex-chem3
.econt
which obtains the following information from the specified computer:
.bc
David Piranha last logged out at 23:47 on 9 May 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.
.end

Noting that the current date is May 14, so that there is no point in
getting the message there quickly, Smith types
.bc
night mail dave@utex-chem3
.break
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).
.econt
The "night mail" command causes the message transmission to be deferred until
inexpensive nighttime telephone rates are in force.

Additional capabilities of the %2Dialnet%1 system can be used to follow up on the
above inquiry, as follows.
.begin indent 0,2; nojust
.at "⊗" ⊂ "%8α⊗%*" ⊃;
⊗ 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.
.end
.s 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 %2Dialnet%1 involves a program in one
computer "waking up" and interacting with a program in
another machine.  %2Dialnet%1 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.

.s 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:

.begin nojust indent 0,3;
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?
.end
.s 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 %2Dialnet%1 community.

%2Note: This document is adapted from our NSF proposal and retains some
of that eleemosynary flavor.%1

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.

This document is DIALNE[W77,JMC] @SU-AI.