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To:@\Charlie Salisbury, Larry Loucks, Alex Morrow

From:@\J. H. Saltzer

Subj:@\AIX usability on the M.I.T. Campus and at Project Athena

Date:@\6 April 1987

@end(Format)

Recently the following question was raised again: What would be
required to make AIX acceptable for use on the M.I.T. campus, where
the Berkeley 4.2/4.3 form of UNIX dominates.  The question is usually
posed in terms of a list of Berkeley 4.3 features that might be added
to AIX.  Unfortunately, the question does not yield to anything as
simple as a list of features.  For one thing, there are several
possible scenarios of application at M.I.T., each having different
requirements.  For another, the list of required features is not easy
to construct; it may be more productive to formulate the discussion in
terms of acceptance tests.

I propose to focus the discussion by defining five increasing levels
of potential acceptance:
@begin(itemize)
Arms-length network attachment.

Integrated network attachment.

Usability for a limited set of Athena services.

Applications Programming Interface coherence for Athena workstations.

User interface coherence
@end(itemize)

The following sections provide, for each of these five levels of
potential acceptance, some estimate of the meaning of requirement, an
acceptance test, and an estimate of the breadth of interest at M.I.T.
in that level of function.  In each case, it is assumed that AIX has
been extended to include various features from the BSD 4.3 system,
with those features in the form that they are used at M.I.T. and
Athena.

@MajorSection(Arms-Length Network Attachment)

With arms-length network attachment, an AIX-based RT can be plugged
into the M.I.T. campus network and can accomplish file transfer, remote
login, and mail exchange without causing disruption to other
systems attached to the same local area network.

@subheading(Requirements)
@begin(itemize)

Implementation of TCP/IP protocol family with Address Resolution
Protocol and subnet routing.

Implementations of (both server and client) telnet, FTP, and SMTP
protocols.

Hardware and software to support both Ethernet and IBM Token Ring.

Support of TCP/IP that responds rapidly and effectively to problems
discovered in the field.  (This requirement is a subtle one that
reflects difficult experiences with certain vendors who have supplied
TCP/IP implementations without sources and then were unable to respond
to problems discovered as the M.I.T. campus network has expanded in both
size and range of host implementations of TCP/IP.)

@end(itemize)

@subheading(Acceptance test)

An RT running AIX is plugged into an Ethernet socket on the M.I.T.
campus and is able to do both client and server telnet, FTP, and SMTP
exchanges with non-AIX machines.  There must be no serious performance
glitches or excessive network-level retries, and no disruption of
other users of the campus network.

The support requirement, while essential, is not amenable to any
obvious acceptance test, and response to it can probably be evaluated
only over a period of time.

@subheading(Applicability)

Any number of research organizations around M.I.T. may have an
interest in joining the RT AIX community while remaining in contact
with the M.I.T. network world.  However, each such organization will
have to be identified and convinced by IBM.

@MajorSection(Integrated Network Attachment)

Integrated network attachment adds several features that make work within
the M.I.T. network community more effective.

@subheading(Requirements)
@begin(itemize)
Implementation of domain name resolution protocol and use in every
function that resolves network names.

Implementation of a SUN Network File System client and integration
into the AIX file system.

Implementation of Post Office Protocol and integration with some
native AIX mail system.

Implementation of Kerberos ticket acquisition and integration with
NFS and POP.

@end(itemize)

@subheading(Acceptance test)

An RT running AIX is able to exchange mail with M.I.T. Post Office
servers and can read and write NFS files, all mediated with Kerberos
authentication.  No changes need be made to the AIX configuration to
accomodate communication with newly added hosts elsewhere at M.I.T. or
in the internet.

@subheading(Applicability)

The ability to use centrally-administered libraries and mail
facilities should increase dramatically the number of potential
customers.

@MajorSection(Usability for a limited set of Athena services)

To be used as an Athena server, the RT with AIX must provide at least
a modest amount of application programming interface coherence with
Berkeley 4.3.

@Subheading(Requirements)

Ability for a limited set of M.I.T.-provided network-oriented
application programs that were implemented for the 4.2A kernel to
operate correctly using the AIX kernel.  These include:
@itemize[

Sun Network File System service

Kerberos Authentication and Key Distribution Service

Remote Virtual Disk (RVD) service

Bind name service

]

@Subheading(Acceptance Test)

The M.I.T. sources and makefiles for the above-named services are
copied to an AIX RT, the "make" command is issued and the resulting
application programs run as services on the AIX RT.

@Subheading(Applicability)

Project Athena has need for several additional servers, especially in the
file storage area.  The AIX operating system, along with the
hardware that it supports, becomes a candidate for use in those server
applications.

@MajorSection(Kernel coherence for Athena workstations)

This level of applicability makes the AIX RT usable throughout Athena.

@Subheading(Requirements)
@begin(itemize)

Ability for user-written applications that were implemented for
Berkeley 4.2 or 4.3 UNIX to operate correctly using the AIX kernel.

Ability for applications that use the X version 11 window system to
operate correctly on AIX.

Ability to operate in the M.I.T. environment with no more than one
per-workstation configuration file.

Availability of kernel sources and kernel build system to allow local
maintenance and analysis of Applications Programming Interface
problems.  Can be proprietary, but can not have confidential methods
and concepts.

@end(itemize)

@Subheading(Acceptance Test)

@begin(enumerate)

The M.I.T. sources and makefiles for the 4.3 user system are copied to
an AIX RT, the "make" command is issued, the resulting set of user
libraries and commands are installed on the AIX RT, the make command
is issued again, and the resulting set of user libraries and commands
works correctly.

A selection of user-written application programs and makefiles can be
moved to an AIX RT, built with a "make" command, and they run
correctly.  (Selection to be made with the advice of Athena
Application Development staff.)

@end(enumerate)

@Subheading(Applicability)

With this level of coherence, the AIX RT would be usable as a standard
Athena workstation, and the acceptance of AIX throughout the M.I.T.
community as a replacement for the Berkeley 4.2 or 4.3 systems would
be substantial.

@MajorSection(User Interface Coherence)

User interface coherence allows the user to work with an AIX RT with
the same user documentation that was provided for a standard Athena
BSD 4.3 workstation.

@subheading(Requirements)

Provision of a complete set of 4.3-compatible user-level programming
libraries and commands.

@Subheading(Acceptance test)

@begin(itemize)

The M.I.T. sources and makefiles for a selection of application
programs are copied to the AIX RT, the "make" command is issued, and
the resulting set of applications works correctly using the native AIX
libraries.

Users find that documentation that was prepared for the 4.2 or 4.3
version of their applications, for UNIX commands and libraries, and
for third-party subsystems is usable.

@end(itemize)

@Subheading(applicability)

The additional applicability of this system over the immediately previous
one may be small.