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Designing the Server

Server must maintain invariant and imply progress:

ServerC,R(server, client, counter) :<=>
   exists i in [1,C]:
         receivei(server, release)  /\ 
            count' = count+1  /\ 
            changed(server, count)
         receivei(server, request)  /\ count > 0  /\ 
            sendi(client, grant)  /\ count' = count-1  /\ 
            changed(server, client, count)
         receivei(server, request)  /\ count <=0  /\ 
receive a release message and increase counter
send a grant message and decrease counter
what now?

Need possibility to defer grant messages.

Author: Wolfgang Schreiner
Last Modification: April 22, 1999

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