“Allowed event conflict”

© Franck.Barbier@FranckBarbier.com

“Allowed event conflict” is a software case study, which is implemented in PauWare. PauWare is a Java engine for executing Harel's Statecharts in general.

Application Programming Interface -API-: Javadoc.

This case study aims at illustrating the notion of “allowed event” in UML. An allowed event does not appear as a label for passing through a transition. Instead, it is assigned to a state meaning that the state machine must react to the allowed event when in this state or any substate of this state. Allowed events assigned to the state machine itself are especially useful for processing events, regardless of the current active state(s) of the state machine.

Since allowed events may conflict with “common” events, this case study may be customized for having different scenarios: change the Boolean values of the g1, g2, g3 and/or, g4 guards in Allowed_event_conflict.java in order to understand PauWare management policy of allowed events against “common” events. Note that the notion of “allowed event” is supported in SCXML.

• Java SE application as a Maven project Allowed_event_conflict.PauWare2Web.zip 

• This application has been designed and tested by means of PauWare ver. 2.0 (a.k.a. PauWare2, Sept. 2021). This application also reuses PauWare2Web, a PauWare2 add-on, which allows the dynamic simulation of Harel's Statecharts in a Web browser. While PauWare2 is based on Java 9, PauWare2Web requires Java 11.
• After downloading Allowed_event_conflict.PauWare2Web.zip , PauWare2 PauWare2.zip  and PauWare2Web PauWare2Web.zip  must be made accessible as Maven dependencies. PauWare2Web itself requires third-party libraries that are downloaded by Maven:
  • Java API for Processing JSON software is linked to PauWare2Web as a runtime library.
  • PlantUML Java software is linked to PauWare2Web as a runtime library.
    • Graphviz software (required by PlantUML) is a priori installed on Windows.
    • Graphviz software on macOS may be installed using Homebrew (see also here…).
  • Tyrus Java software is linked to PauWare2Web as a runtime library.
• Note that PauWare2Web can be bypassed in the code (no Web visualization then) by commenting/removing in Allowed_event_conflict.java what follows:

_Allowed_event_conflict_state_machine = new com.pauware.pauware_engine.Core.StateMachine(… /*, new com.pauware.pauware2web.PauWare2Web_client()*/);