PPT Slide
I = (P1,P2)s => service center representing a unique service P1 followed by P2, expressing sequentiality (P1 and P2 are not concurrent)
I = (P1,P2)a => service center with infinite buffer implicitely modelling the communication channel + the transition P1 ->P2 in the QNM
{(P1,P2)s, (P1,P3)s }ND => multi-customer service center
synchronous communication among concurrent components =>distinct service centers, the receiver component a zero capacity buffer with BAS policy in the sender component