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Date: 10 Sep 91 22:00:36 GMT
From: porthos!taichi!haim@bellcore.com  (24122-Haim Kilov(L028)m000)
Subject: Re: Large System Decomposition
Message-ID: <1991Sep10.220036.20777@porthos.cc.bellcore.com>
List-Id: <comp.lang.ada>

"Think of your project interms of what OSI calls Managed Objects,
which are resource encapsulations hiding behind a message based
interopable interface. Don't think in terms of subsytems or
function calls, it won't work. Think of the higher levels
of your system as active objects, modeled by processes or tasks
which must talk to each other through a well defined message
protocol, over a communication link. Don't think client server
or agent architecture unless it fits the needs of your Managed Objects."

--Don't forget, however, about relationships between managed objects that,
quoting the new draft of ISO standard, are "significant entities, warranting
conceptual attention". This draft attempts to provide formal specification
tools for relationships -- we have done it already for generic relationships
of different meta-types here in Bellcore. These specifications are
formulated using behavioral properties of an entity (call it "managed object")
and its associated entities. The same approach is recommended by the recently
accepted ANSI OODBTG Object Data Management reference Model.

As I had mentioned some time ago, Bellcore Special Report "Information modeling
concepts and guidelines" discusses some of these issues at some length.
Some other papers/documents will be published.

Hope this helps.

Haim Kilov
haim@bcr.cc.bellcore.com