Communication by open process and read or write instructions

com41901 (starnet!apple!risp3.CSELT.STET.IT!com41901)
Wed, 20 Apr 1994 10:25:30 +0100

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from
Paolo Austa
C.S.E.L.T. telecom labs
via Reiss Romoli 248
Torino
ITALY
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I'm a new user of Metacard and I need some help,
in particular I have some questions about communication
with processes by the "open process" instruction :
Suppose you have a process "proc"that is a simple loop
writing in its stdout a set of strings "msg 1" ... "msg n"
Now if I try to read from that process by the
"read from process"
instruction that set of string seems to be available only
when the process "proc" terminates.

- Now, how can I read from the process "proc" a string exactly
after it has been printed out ? ( Note that the process "proc" could be
an infinite loop and in this case a "read" instruction blocks
Metacard since it waits for the termination of a process that
never terminates).

- Which is the Unix-based mechanism underlying this type of
communication?

Thanks

Paolo.

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