🚀 go-pugleaf

In case you missed it, here is the original MAP/TOP statement.  MAP/TOP
is a U.S. consortium of industrial computer users, including General
Motors, Boeing, etc.  They are one of the largest groups of OSI users
in the U.S. and are very influential with U.S. and computer networking
international standards.

ANSI, the U.S. standards organization, is standardizing the X Window
System protocol.  Part of this work may include an OSI protocol
mapping.  There is currently a debate (including theoretical work and
prototyping) within ANSI as to whether this mapping should be at the
ACSE level or Transport level.  Detailed protocol mapping for each
have been submitted.

If you have comments on this issue, please contact me this week.  The
ANSI window systems committee will be meeting next week (Jan. 12-16) to
try to resolve this issue.

Ken Lee
Secretary, ANSI X3H3.6 (Computer Graphics - Window Systems)
klee@decwrl.dec.com
==============================================================

Manufacturing Automation Protocol &
Technical and Office Protocol Users Group

89-00-002-ARC

December 13, 1989


                      MAP/TOP LIAISON TO ANSI X3H3.6


A high priority requirement of the MAP/TOP Users Group is to use X-Window
over OSI networks.  As the MAP/TOP Users Group is committed to use interna-
tional or national standards whenever possible, it welcomes the work X3H3
is doing to standardize the X-Data Stream.

However, the MAP/TOP Users Group not only needs a Data Stream standard, but
also needs a standardized mapping of the X-Data Stream Definition onto OSI.
Without a standardized mapping, there is no way of ensuring interoperabil-
ity of implementations of the X-Data Stream from different vendors over OSI
networks.

To promote the timely adoption of such a mapping, the MAP/TOP Users Group
sent X3H3 a position statement in September 1989 (see 89-00-0002 USG)
encouraging X3H3 to include in the X-Data Stream standard a mapping at the
ACSE/Presentation level of OSI.  As X3H3 has not yet made a decision on the
type of mapping to incorporate in the X-Data Stream definition, the MAP/TOP
Users Group wishes to reiterate its position that the mapping should be on
the ACSE/Presentation level of OSI.  We hope the following will help X3H3
understand the reasons behind this position:

1.   OSI Naming and Addressing (See ISO 7498-2) comprises all seven layers.
     Addressing at the ACSE level will enable an X-Client to address an X-
     Server in a standard manner, but some ad hoc addressing mechanism
     would have to be invented to handle client addressing at a lower
     level.

2.   OSI Security is provide by functions in the Application Layer of OSI.
     Thus, OSI access control facility will not be available below the
     Application Layer.

3.   OSI Directory services is an Application Layer function.  It is highly
     desirable that X-Applications be able to locate X-Servers through a
     standard use of X-500 Directories.

4.   In the event of loss of communication, re-establishment to a particu-
     lar instance of a process is available only in OSI if ACSE is
     employed.

5.   If a Client application or a Server using the X-Data Stream Definition
     is also going to use other OSI protocols (e.g., VT for process selec-
     tion or FTAM for down loading fonts), implementation consistency (sin-
     gle OSI interface) will be achieved only if these protocols operate at









                                   - 2 -


     the same level of OSI (i.e., ACSE).

6.   Mapping to the ACSE/Presentation level of OSI is architecturally (for
     OSI) correct.  We believe that if X-Data Stream is not mapped to use
     OSI at this level, there may be some negative reaction from the OSI
     committees in ISO and ISO National Bodies.  This could hinder the
     fast-track process for the X-Data Stream Definition standard.  As our
     goal is to get an international X-Data Stream Definition as quickly as
     possible, we strongly advise against doing anything which could jeop-
     ardize the rapid progression of your standard in ISO.

X-Data Stream on OSI Prototyping

In discussing the X-Data Stream Definition/OSI mapping at the Technical
Forum meeting of December 11, 1989, it was reported that X3H3 is awaiting
the results of prototyping work to help make the decision as to which map-
ping to choose.  We see prototyping as a valuable tool to determine if a
mapping candidate is correct.  It is far better to ensure accuracy before
the standard goes to Public Review.

However, a few implementors at our meeting cautioned against attaching too
much weight on these results with regard to efficiency.  As these implemen-
tations are just prototypes and not finished products, they will probably
not receive the attention and tuning for efficiency a finished product
would receive.  Therefore, we feel performance figures from these proto-
types probably are not indicative of the performance levels which can be
expected of X-Window products based on the X-Data Stream Definition.  For
example, a prototype may utilize the user interface to gain access to OSI
services, whereas an X-Product may bypass such an interface and use a fas-
ter internal OSI service interface.

CONCLUSION

In view of the above, the MAP/TOP Users Group urges X3H3 to adopt an
ACSE/Presentation mapping and to progress this mapping with the X-Data
Stream Definition as quickly as possible.



Ken Lee
DEC Western Software Laboratory, Palo Alto, Calif.
Internet: klee@decwrl.dec.com
uucp: uunet!decwrl!klee