Fork me on GitHub

Sample State Machine

This is a sample state machine.

Definition

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
var elevator = new PassiveStateMachine<States, Events>("Elevator");
 
elevator.DefineHierarchyOn(States.Healthy)
    .WithHistoryType(HistoryType.Deep)
    .WithInitialSubState(States.OnFloor)
    .WithSubState(States.Moving);
elevator.DefineHierarchyOn(States.Moving)
    .WithHistoryType(HistoryType.Shallow)
    .WithInitialSubState(States.MovingUp)
    .WithSubState(States.MovingDown);
elevator.DefineHierarchyOn(States.OnFloor)
    .WithHistoryType(HistoryType.None)
    .WithInitialSubState(States.DoorClosed)
    .WithSubState(States.DoorOpen);
 
elevator.In(States.Healthy)
    .On(Events.ErrorOccured).Goto(States.Error);
 
elevator.In(States.Error)
    .On(Events.Reset).Goto(States.Healthy)
    .On(Events.ErrorOccured);
 
elevator.In(States.OnFloor)
    .ExecuteOnEntry(this.AnnounceFloor)
    .ExecuteOnExit(Beep)
    .ExecuteOnExit(Beep) // just beep a second time
    .On(Events.CloseDoor).Goto(States.DoorClosed)
    .On(Events.OpenDoor).Goto(States.DoorOpen)
    .On(Events.GoUp)
        .If(CheckOverload).Goto(States.MovingUp)
        .Otherwise().Execute(this.AnnounceOverload, Beep)
    .On(Events.GoDown)
        .If(CheckOverload).Goto(States.MovingDown)
        .Otherwise().Execute(this.AnnounceOverload);
 
elevator.In(States.Moving)
    .On(Events.Stop).Goto(States.OnFloor);
 
elevator.Initialize(States.OnFloor);

The above state machine uses these actions and guards:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
private void AnnounceFloor()
{
    /* announce floor number */
}
 
private void AnnounceOverload()
{
    /* announce overload */
}
 
private void Beep()
{
    /* beep */
}
 
private bool CheckOverload()
{
    return whetherElevatorHasOverload;
}

Run the State Machine

This is a small sample to show how to interact with the state machine:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
// queue some events to be performed when state machine is started.
elevator.Fire(Events.ErrorOccured);
elevator.Fire(Events.Reset);
             
elevator.Start();
 
// these events are performed immediately
elevator.Fire(Events.OpenDoor);
elevator.Fire(Events.CloseDoor);
elevator.Fire(Events.GoUp);
elevator.Fire(Events.Stop);
elevator.Fire(Events.OpenDoor);
 
elevator.Stop();

Log

If you add the log4net log extensions available in the Appccelerate.SourceTemplate package:

1
elevator.AddExtension(new Appccelerate.Log4Net.StateMachineLogExtension<States, Events>("Elevator"));

to the above code then these are the log messages (if all are enabled - see log4net documentation on how to configure log messages). Note how the state exits and enters are logged, especially for hierarchical transitions.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Logger      Level   Message
Elevator    INFO    State machine Elevator initializes to state OnFloor.
Elevator    INFO    State machine Elevator switched from state  to state DoorClosed.
Elevator    DEBUG    State machine Elevator performed  -> Enter Healthy -> Enter OnFloor -> Enter DoorClosed.
Elevator    INFO    Fire event ErrorOccured on state machine Elevator with current state DoorClosed and event arguments .
Elevator    INFO    State machine Elevator switched from state DoorClosed to state Error.
Elevator    DEBUG    State machine Elevator performed  -> Exit DoorClosed -> Exit OnFloor -> Exit Healthy -> Enter Error.
Elevator    INFO    Fire event Reset on state machine Elevator with current state Error and event arguments .
Elevator    INFO    State machine Elevator switched from state Error to state DoorClosed.
Elevator    DEBUG    State machine Elevator performed  -> Exit Error -> Enter Healthy -> Enter OnFloor -> Enter DoorClosed.
Elevator    INFO    Fire event OpenDoor on state machine Elevator with current state DoorClosed and event arguments .
Elevator    INFO    State machine Elevator switched from state DoorClosed to state DoorOpen.
Elevator    DEBUG    State machine Elevator performed  -> Exit DoorClosed -> Enter DoorOpen.
Elevator    INFO    Fire event CloseDoor on state machine Elevator with current state DoorOpen and event arguments .
Elevator    INFO    State machine Elevator switched from state DoorOpen to state DoorClosed.
Elevator    DEBUG    State machine Elevator performed  -> Exit DoorOpen -> Enter DoorClosed.
Elevator    INFO    Fire event GoUp on state machine Elevator with current state DoorClosed and event arguments .
Elevator    INFO    State machine Elevator switched from state DoorClosed to state MovingUp.
Elevator    DEBUG    State machine Elevator performed  -> Exit DoorClosed -> Exit OnFloor -> Enter Moving -> Enter MovingUp.
Elevator    INFO    Fire event Stop on state machine Elevator with current state MovingUp and event arguments .
Elevator    INFO    State machine Elevator switched from state MovingUp to state DoorClosed.
Elevator    DEBUG    State machine Elevator performed  -> Exit MovingUp -> Exit Moving -> Enter OnFloor -> Enter DoorClosed.
Elevator    INFO    Fire event OpenDoor on state machine Elevator with current state DoorClosed and event arguments .
Elevator    INFO    State machine Elevator switched from state DoorClosed to state DoorOpen.
Elevator    DEBUG    State machine Elevator performed  -> Exit DoorClosed -> Enter DoorOpen.

You can write your own extension for different logging.

Reports

yEd Report

sample yEd report

csv Report

SourceEntryExitChildren
OnFloorAnnounceFloorBeep, BeepDoorClosed, DoorOpen
Moving MovingUp, MovingDown
Healthy OnFloor, Moving
MovingUp
MovingDown
DoorClosed
DoorOpen
Error
SourceEventGuardTargetActions
OnFloorCloseDoorDoorClosed
OnFloorOpenDoorDoorOpen
OnFloorGoUpCheckOverloadMovingUp
OnFloorGoUp internal transition AnnounceOverload, Beep
OnFloorGoDownCheckOverloadMovingDown
OnFloorGoDowninternal transition AnnounceOverload
MovingStopOnFloor
HealthyErrorOccured Error
ErrorResetHealthy
ErrorErrorOccuredinternal transition

Textual Report

Elevator: initial state = OnFloor
    Healthy: initial state = OnFloor history type = Deep
        entry action: 
        exit action: 
        ErrorOccured -> Error actions:  guard: 
        OnFloor: initial state = DoorClosed history type = None
            entry action: AnnounceFloor
            exit action: Beep, Beep
            CloseDoor -> DoorClosed actions:  guard: 
            OpenDoor -> DoorOpen actions:  guard: 
            GoUp -> MovingUp actions:  guard: CheckOverload
            GoUp -> internal actions: AnnounceOverload, Beep guard: 
            GoDown -> MovingDown actions:  guard: CheckOverload
            GoDown -> internal actions: AnnounceOverload guard: 
            DoorClosed: initial state = None history type = None
                entry action: 
                exit action: 
            DoorOpen: initial state = None history type = None
                entry action: 
                exit action: 
        Moving: initial state = MovingUp history type = Shallow
            entry action: 
            exit action: 
            Stop -> OnFloor actions:  guard: 
            MovingUp: initial state = None history type = None
                entry action: 
                exit action: 
            MovingDown: initial state = None history type = None
                entry action: 
                exit action: 
    Error: initial state = None history type = None
        entry action: 
        exit action: 
        Reset -> Healthy actions:  guard: 
        ErrorOccured -> internal actions:  guard: 
Back to Top