representation of interfaces to the messaging service

[mwsachs@us.ibm.com]

There is an inter-layer interface representation that some standards use,
which I have seen referred to as the OSI interface model. It is considered
to be technology and implementation independent and definitely won't be
confused with an API. It is expressed in natural language.

Consider a 2-layer structure, TOP and BOTTOM.  The conceptual interface
between the TOP and BOTTOM is expressed in terms of four primitives:

   Request:  TOP makes a request to BOTTOM for a specified service.
   Indication:  BOTTOM sends a particular signal to TOP
   Response:  TOP sends the results of the previous Indication to BOTTOM.
   Confirm:  BOTTOM conveys the results of one or more service requests to
   TOP.

The specific request, etc. and the name of the "sending" level are
concatenated to the primitive name thus: TOP_Data.Request.

Text associated with the primitive specifies the characteristics of the
primitive, such as when generated, effect on receipt, and status.

Associated with naming the primitive is a brief description of the
semantics (typically one sentence).

Examples of this are in the ANSI Fibre Channel Physical and Signaling
Interface specification which I unfortunately have only on paper.

I mention this only to add to the spectrum of choice.  It is highly likely
that the BP-TRP interface will have to be in UML to mesh with the BP meta
model. This OSI interface representation is not anywhere as rich as UML but
it is a compact easily understood representation.  If we use a UML model,
we will certainly have to add the same kind of explanatory text.

Regards,
Marty



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Martin W. Sachs
IBM T. J. Watson Research Center
P. O. B. 704
Yorktown Hts, NY 10598
914-784-7287;  IBM tie line 863-7287
Notes address:  Martin W Sachs/Watson/IBM
Internet address:  mwsachs @ us.ibm.com
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