A
Petri net (also known as a
place/transition net or
P/T net) is one of several
mathematical modeling languages for the description of
distributed systems.

Petri Net System includes graphical designer for drawing networks, and a run time engine for simulating and running networks, code templates facilitating associated development activities, and a lightweight web server for controlling instrumentation via HTTP requests.
Petri Net Designer


Petri Net Simulator could be a VB.NET or C# project.