Re: SDL-News: How to share variables among processes?

Subject: Re: SDL-News: How to share variables among processes?
From: Elie Cohen (
Date: Mon Jan 25 1999 - 04:42:24 GMT

The originator of this message is responsible for its content.
-----From "Elie Cohen" <> to sdlnews -----

Hello Gary,

There are exactly 4 ways for two processes to share data.

1/ Process P1 sends a signal to process P2. The signal can carry data, P2
gets a COPY and is free to do whatever it "wants" with it.

2/ Process P1 creates process P2 and can pass parameters at that time. One
time, one way exchange.

3/ P1 exports or reveals variables. P2 imports or views. For view/reveal, P1
and P2 must be in the same block. No such restriction if they use

4/ In SDL'92 and '96, there is a support for RPC (remote procedure call): P1
exports a procedures. P2 calls that procedure, thereby getting some sort of
access to P1's "state" at that point.

In option 3 where P1 makes a variable visible to other processes, P1 keeps
full ownership and control of that variable, as P2 can only READ the value
of the shared variable. If P2 needs changes made, it must request that
change from P1, typically by sending a signal.

Elie Cohen / Engineering Manager / tel: 972 241 6595 x13 / fax: 972 241 6494
VERILOG, Inc. / 3010 LBJ Fwy, Suite 900 / Dallas TX 75234 /
Stuck with your maintenance, coding, quality issues?
Try and Buy C CodeWatch for Windows at

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