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13. Petrinet Design of a Whiteboard Voting System

Werner Van Belle1 - werner@yellowcouch.org, werner.van.belle@gmail.com

1- Programming Technology Lab (PROG) Department of Computer Science (DINF) Vrije Universiteit Brussel (VUB); Pleinlaan 2; 1050 Brussel; Belgium

Abstract :  Continues upon the previous excercise. In this exercise we model a voting system using Petrinets. This exercise was givemn in 2002-2003

Reference:  Werner Van Belle; Petrinet Design of a Whiteboard Voting System;

Exercise 1: Design of a voting system

In this exercise we will try to draw the schematics of our previous used 'vote to continue' strategy. However, we will do this in steps.
  • Draw a CPNet of a repeater. This CPNet should have the following places: 'inmessage', 'outmessage', connected' and 'repeating'.
  • Extend this Petri-net with the following places: 'timeout”, 'dead', 'connect'. The timeout place receives a token if a client times out when sending a message. The dead place should contain all clients that are dead and the connect place contains a token if a client connects (or reconnects).
  • Extend the Petri-net to flush outgoing messages to dead clients.
  • Extend the Petri-net with a transition that goes from repeating to blocking in such a way that the Petri-net behaves correct.
  • Change the connected and dead places so that, the number of elements is known.
  • Extend the popping of incoming messages such that a differentiation on ordinary messages and voting messages is possible.
  • Finish the exercise...
  • 2 Exercise 2: Implementation

    Given the Petri-net investigate how you can implement it.