Simple protocol examples in PN Not surprisingly Petri Net models can capture control protocols in collaborative situations as well as in more traditional engineered systems. For example, Figure 1 shows a simple Petri Net in which participants in a meeting are either listening or talking. An oral meeting model in which a participant p may take the floor at any time and a speaker t may release the floor at any time. There is no limit on the number of simultaneous speakers. An oral meeting model in which there can be at most one speaker at a time and interruption is allowed.
L responds affirmatively to an offer from the speaker s to take the floor.
An oral meeting model in which the speaker t may invite another participant p from the listener place L to take the floor. The transition is guarded so as to be enabled to fire only if there is an affirmative Rsvp. Priority queuing is commonly used to manage access to a resource. Figure 3 is a Petri Net model which combines elements from the previous examples to define a first come, first served priority queue. When they do so, a priority number y is assigned and the next available y value is incremented.