EMAIL server FSP model

For my assignment I need to develop FSP model for email server and client. I manage to write simple model which describes one user, server and his mailbox, but I am having problems changing this system into one which have two users with two separate mailboxes.

The FSP model that I have开发者_开发技巧 developed:

USER = (read->USER | write->USER).
SERVER = (read->get->SERVER | write->put->SERVER).
MAILBOX(N=0) = MAILBOX[N],
MAILBOX[i:0..3] = (when (i<3) write->put->MAILBOX[i+1]
 | when (i>0) read->get->MAILBOX[i-1]).
||EMAIL = (USER || SERVER || MAILBOX).

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What about if u try this:

USERX = (read->USERX | write->USERX).
USERY = (read->USERY | write->USERY).


MAILBOX(N=3) = X[N],
X[i:0..N] = (when (i<3) write->put->X[i+1] 
| when (i>0) read->get->X[i-1]).

MAILBOX1(N=3) = Y[N],
Y[j:0..N] = (when (j<3) write->put->Y[j+1] 
| when (j>0) read->get->Y[j-1]).



SERVER = (read->get->SERVER | write->put->SERVER).

||EMAIL = (USERX || USERY || SERVER || MAILBOX ||  MAILBOX1).