This work presents a technique of early simulation in the design phase of c
oncurrent and distributed systems. A P/T net is used to model the system wh
ose behavior is simulated by the net execution; the truly concurrent semant
ics of P/T nets establishes a partial order among the system events. The de
signer can interact with the simulator asking for measures about the system
behavior that concern all executions respecting the same partial order. So
me measures. such as the degree of parallelism exploited, are not easily ob
tainable from an interleaving semantics. Moreover, the designer can force t
he system behavior to reflect resource-constrained environments. (C) 2001 E
lsevier Science B.V. All rights reserved.