Subject: RE: SDL-News: Communication between processes in different blocks
From: Bernd Grahlmann (bernd#informatik.uni-hildesheim.de )
Date: Tue Aug 11 1998 - 12:51:10 GMT
The originator of this message is responsible for its content.
-----From bernd#informatik.uni-hildesheim.de (Bernd Grahlmann) to sdlnews -----
> Some Code Generators generate the addresses for the process instances in
> a deterministic way. For example in CMicro of SDT, the PID is implemented
> as an integer, where the lower order byte represents the Process type
> (determined at the compile time) and the higher orde byte indicates the
> instance number of that process. This means that even without having a
> manager process the PID of the destination process instance can be
> calculated and this can be used in the TO Pid construct. For example if
> you want to send a signal to the 3rd instance of process A then you have
> to get the process type value and calculate the PID value using the
> process type value and the instance. This method will be more efficient
> than using a manager process, but may not be an elegant soluton as it
> depends on the internals of the code generator.
Indeed, and moreover your problems become more severe if you also
take dynamic process termination and creation into account. Maybe, you have
up to two instances: the first instance creates a second and then terminates,
the second creates a new one (the third or first - as you like) and terminates,
and so on ...
Another problem may be, that you may perhaps want to perform verification.
In this case, you have to make sure that your verifier checks the same behaviour.
Cheers,
Bernd
*********************************************************************
Bernd Grahlmann Universit"at Hildesheim
Dipl. Inform. Institut f"ur Informatik
Telefon (+49) 05121 / 883 -760 /-740 Samelsonplatz 1
Telefax (+49) 05121 / 860 475 D-31141 Hildesheim
bernd#informatik.uni-hildesheim.de
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