/** Two SDL processes - Example of Figure 12.1 in book by Braek
 *  
 *  Gregor v. Bochmann, January 2009 */

// les deux processus SDL ("rar" stands for Ra received; "sbs" stands for Gb sent; etc )
A = (rar -> sbs -> gbr -> aas -> ear -> qbs -> A  |  sar -> gas -> qar -> A).
B = (rbr -> sas -> gar -> abs -> ebr -> qas -> B  |  sbr -> gbs -> qbr -> B).

// medium de communication de A vers B
MAB = (gas -> gar -> MAB | sbs -> sbr -> MAB | qbs -> qbr -> MAB). 

// medium de communication de A vers B
MBA = (gbs -> gbr -> MBA | sas -> sar -> MBA | qas -> qar -> MBA). 

// the composition of these four components
||SYS = (A || B || MAB || MBA).