OSI Upper-Layer Communications for Applications (skinstak)

Status: Concluded February, 1993 
 Peter Furniss 
Description of Working Group:
Application protocols originally designed for use over TCP can
effectively use the upper-layers of OSI, that is the ACSE (Association
Control Service Element), Presentation and Session protocols as their
``transport'' mechanism. The IPS application protocol is thus migrated
to be another OSI protocol, and could subsequently be integrated with
other OSI application protocols. The communication requirements of
such application protocols are essentially connect, read and write.
This can be met by the OSI upper-layer protocols, using only their
basic features. However, for such a migration there need to be a) a
specification of the use of various OSI parameters and fields for this
purpose, b) interfaces to OSI that are as close as possible to those
for original supporting IPS protocols, and c) OSI implementations of
reasonable efficiency
Item a) is essential for interworking at all, b) is needed to reduce the
conversion effort, and c) to make the migrated application usable.  The
``skinny stack'' approach, where the OSI implementation provides only
those features needed by the application is a possible solution to c).
The intent of the group is to identify the requirements for a) and
develop the specifications for b). Other groups are also planning to
consider different aspects of these.
For a), the North American OSI implementors workshop (OIW) intend
developing profiles for basic communications using the upper-layers, but
there are important addressing and other questions that are specific to
TCP to OSI migration.
For b), it is intended that the IETF working group should consider
specification of the use of the socket interface to access the OSI upper-
layers. This will define representations of those OSI protocol fields that
need to be available to the programmer and specify values for those
that can be fixed.
Although the initial work will concentrate on ex-TCP migrants,
consideration will also be given to ex-UDP migrants and, especially for
the interface aspects, to further extending the interface to provide
access to other OSI parameters/fields. This would allow new application
protocols, specified initially for use over OSI, to be built using the
socket interface.
Although the mapping will be supportable using ``skinny stacks''
(minimal functionality implementations), it will define conformant use of
the OSI protocols and so can be achieved by general-purpose OSI
No special remote management issues are expected - remote
management will be by the usual methods for the environment.
Security issues will include whether ACSE-authentication should be