Courier-Protocol


The Courier-protocol describes a unidirectional communication protocol. A Petri-net specification of the protocol has been first published in [1]. In [2] the protocol is used as an example to show the generation of hierarchical automata networks from Petri-net specifications.

APNN-Description

The model is described as a hierarchical net with 4 subnets. Subnets communicate via shared transitions. The hierarchical description corresponds to a partition of the set of places such that each subnet specifies one automaton/component of the net. The transitions visible in the upper level are all synchronized transitions, the remaining transitions inside the subnets are local. Transitions rates in the model are identical to the rates given in [1].
The state space size of the model is scalable by the window size which corresponds to the number of tokens  in the initial marking of the places p14 of subnet sender_transport_layer. The size of the state space for different window sizes can be found in [2].




Automata-Description

The automata description of the example includes the matrices for a model with window size 3 which results in a CTMC with 419,400 reachable states and 2,281,620 transitions.

References

  1. C. M. Woodside, Y. Li: Performance Petri net analysis of communications protocol software by delay equivalent aggregation. Proc. PNPM'91, IEEE CS-Press, 1991, pp. 64-73.
  2. P. Buchholz: Hierarchical structuring of superposed GSPNs. IEEE Trans. on Software Engineering 25, 1999, pp. 166-181.