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Path: utzoo!utgpu!watmath!att!tut.cis.ohio-state.edu!ucbvax!COMMUNITY-CHEST.MITRE.ORG!davis
From: davis@COMMUNITY-CHEST.MITRE.ORG (dave davis)
Newsgroups: comp.lang.ada
Subject: Handling objects in a distributed system
Message-ID: <8908081649.AA02434@chance.mitre.org>
Date: 8 Aug 89 16:48:59 GMT
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List-Id: <comp.lang.ada>


Ed Berard poses an issue in dealing with objects in a distributed 
system:  how to send an object to another node.  As Ed suggests, 
one solution is to have the knowledge of all the objects within the 
system be present at each node.  However, this might be inefficient 
in certain cases, and could cause difficulties if we with to create 
new objects dynamically.

I suggest that an approach would be to transmit "installation
instructions" (or template, or frame) with each transmitted object so
that the recieving node only needs to know a general schema for object
installation.  The instructions would have to contain information
about the object's interface, its last state, and enough information
about its structure to recreate it locally.  Assuming for a moment
that all of the objects in our system are created from more primitive
objects the mechanism need only have a representative of each
primitive object on hand, and know how to apply them in a specific
case.  Such a mechanism could also be two-way, translating objects
to/from non-objective representations.  This mechanism might also be
of use in storing and retrieving persistent objects off-line.

=================================================================
Dave Davis
MITRE Corp;
McLean, VA