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From: burke@netcom.UUCP (Jim Burke)
Newsgroups: comp.object,comp.lang.c++
Subject: Re: Choice of language for manufacturing Applications
Message-ID: <11936@netcom.UUCP>
Date: 14 Aug 90 03:39:37 GMT
References: <37938@ucbvax.BERKELEY.EDU> <5427@stpstn.UUCP> <1990Aug7.165255.5174@swbatl.sbc.com>
Organization: NetCom- The Bay Area's Public Access Unix System {408 241-9760 guest}
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In article <1990Aug7.165255.5174@swbatl.sbc.com> jmd@swbatl.sbc.com (Jim Doherty 5-0804 11-Y-03) writes:
>
>	Objective-C because it follows the smalltalk model of messaging is easily
>extendable across process spaces, for instance:
>
>
>
>		One item I have not mentioned yet is that in order to to accomplish
>the programs must be multi threaded, ie able to give up control in light of
>an external event (a message). to accomplish this we used a unique trick in 
>the _msg code we also put in an accept_events() function call which in 
>reality makes the program(object) multi threaded with out the programmer 
>having knowledge of this. We also linked in a LWP lib (light weight process)
>in the linkage section.

There is a fairly simple alternative to forcing programs to be multi-threaded
in order to accomplish interprocess messaging of objects.  I was heavily
involved in a project development effort in which we solved that problem by
considering process spaces to be purely generic.  Any object could process
it's messages in any process space.  Objects were divorced from the concept
of a process space by giving them existence external to the process in the
form of persistence in a database, residence in shared memory, or even
residence on another node.  The OO message kernal software handled the
routing of the messages and the mapping of the object into a generic process
space for processing.  A dirty flag was set for persistent objects for
rewritting back to the database, if that was where the object lived.  The
only local objects to the process were the actual object management objects,
not application objects.  It was a very slick concept, and one I wish others
would explore and extend...


-- 
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*  Jim Burke                                  James Burke & Associates, Inc.
*  and yes, I do                                     San Jose, CA  95129        
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