Re: SDL-News: External procedures

Subject: Re: SDL-News: External procedures
From: Martin v. Loewis (
Date: Mon Oct 27 1997 - 17:31:51 GMT

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-----From "Martin v. Loewis" <> to sdlnews -----

> We were wondering if the reverse concept of external procedures exist.
> That is to say, can the environment call a procedure inside the SDL
> system instead of sending a signal ?
> To our knowledge no, but we want to be sure of that and therefore need an
> expert confirmation.

Indeed, the idea of the environment calling procedures is not part
of SDL. In order to call a procedure, you need the context of a
process, so that things like signal input or timer set work inside the

However, it is definitely possible to call an exported procedure from
the environment. The call would be performed inside the process that
exports the procedure, but the results would be returned to the caller
in the environment.

As you might know, remote procedures are modelled using signal
exchange, but give a more convenient notation. Whether RPCs are
more convenient to the caller in the environment probably depends on
the environment.


-----End text from "Martin v. Loewis" <> to sdlnews -----
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