Path: utzoo!utgpu!water!watmath!clyde!att-cb!att-ih!pacbell!ames!pasteur!agate!violet.berkeley.edu!pete
From: pete@violet.berkeley.edu
Newsgroups: comp.sys.amiga
Subject: Re: IPC - A proposal
Message-ID: <7545@agate.BERKELEY.EDU>
Date: 9 Mar 88 10:51:12 GMT
References: <8803081858.AA07450@cory.Berkeley.EDU>
Sender: usenet@agate.BERKELEY.EDU
Reply-To: pete@violet.berkeley.edu.UUCP ( Pete Goodeve )
Organization: University of California, Berkeley
Lines: 40


[Apologies if this appears twice anywhere... my first sending seems to have
been eaten -- at least locally! ]

In article <8803081858.AA07450@cory.Berkeley.EDU> dillon@CORY.BERKELEY.EDU (Matt Dillon) writes:

>         You guys don't think big enough!  Don't use an exec message
> structure, use an exec IOStdReq request structure (which is headed by
> an exec message structure).    ......

What in the Guru's name would that buy you?  We aren't interested in all
the baggage that goes into an IO request.  Just a standard basic message
structure that will prevent misunderstanding between programs, and will be
easy for people to incorporate into their stuff.


> .....                       Remember that somebody might want to
> pass a HUGE buffer (say, a BitMap) which can certainly be more than
> 64K, and would want to pass it by reference.

I thought that that was exactly what I was suggesting.... Big buffers
get pointers rather than being copied.  (And of course what is pointed
to will have a size slot in some recognized place, probably in the message
too.) It's obvious.

>         Half hazardly sticking in thousands of 'special' messages all
> in different formats is a quick way to get nowhere... because nobody
> will use the system.

Exactly. But exactly NOT what we have proposed.  The concept is totally
parallel to the IFF philosophy -- but a lot simpler because MOST messages
will be very short.  We need a mechanism which lets a program know what the
message it's just received contains.  A common envelope with an ID header
in a fixed place makes it very easy for a program to decide whether it
knows about that kind of message.  Particular ID header codes will be
publicly announced with the associated format by the people first
developing that kind of data (as Peter da Silva has already done with his
'BRWS' ID).

                                            -- Pete --