Introducing Messages in Modelica for Facilitating Discrete-Event System Modeling

The work performed by the authors to provide to Modelica more discrete-event system modeling functionalities is presented. These functionalities include the replication of the modeling capacities found in the Arena environment, the SIMAN language and the DEVS formalism. The implementation of these new functionalities is included in three free Modelica libraries called ARENALib, SIMANLib and DEVSLib. These libraries also include capacities for random number and variates generation, and dynamic memory management. They are freely available for download at http://www.euclides.dia.uned.es/. As observed in the work performed, discrete-event system modeling with Modelica using the process-oriented approach is difficult and complex. The convenience to include a new concept in the Modelica language has been observed and is discussed in this contribution. This new concept corresponds to the model communication mechanism using messages. Messages help to describe the communication between components in a discrete-event system. They do not substitute the current discrete-event modeling capabilities of Modelica, but extend them. The proposed messages mechanism in Modelica is discussed in the manuscript. An implementation of the messages mechanism is also proposed.