Hermes: A Tutorial and Reference Manual - Researcher - IBM

InputPort,OutputPort,CallmessageTypeFamilies 11811.7.VariantOperations 11.8ProcessCreationandCommunication type{construction
::=callmessage(
::=inportofcallmessage{typeentry{typestate ...] )[constant{parameters] exitexit{typestate [user{exception]... [minimum] [component{declaration[,component{declaration]
constant{parameters ::=constant([component{name[,component{name]... ::=outportofinport{type
Thetypefamiliesinputport,outputport,andcallmessageareusedin \programming-in-the-large"|thatis,thedivisionofsystemsintoprocesses, minimum::=minimumminimum{typestate user{exception ::=exceptionuser{exception{nameexception{typestate ])
thecreationofprocesses,thecreationofbindingsbetweenprocesses,and
type,and(2)aformaltypestate,calledtheentrytypestate. portsorentriesarenotvaluesofvariables. inportvaluesarestoredininportvariablesjustasintegerorstringvalues made.ItshouldbeemphasizedthatinHermesinportsarevalues,andthat arestoredinintegerorstringvariables.Thisiscompletelyconsistentwith therestofHermes,butmightappear\dierent"becauseinmanylanguages thecommunicationbetweenprocesses.
Usuallythemessagetypewillbeacallmessagetype.However,themessagetypecanbeanytype,sincesendcanbeusetotransmitanyvalueto
aninport. callmessage,sinceallcallstatementswillgenerateinitializedcallmessages, willhavewhensent.Youmayomitinit(*)fromtheformaltypestateofa andusingsendtodeliveranuninitializedcallmessageispointless. Aninporttypedenitionspecies(1)atypename,calledthemessage Aninputportorinportisamessagequeuetowhichconnectionscanbe
Theentrytypestateisthetypestatethatvaluesofthemessagetype