1. State transition modeling
Jarosław Kuchta
Embedded Systems Software Engineering
State transition modeling
GUT - INTEL 2015/16
Embedded Systems Software Engineering

2. Embedded Systems Software Engineering
Basic concepts (1)
state – a situation during an object life time, when it satisfies some condition, performs some activity, or waits for some event
event – occurring of some situation which is important in some context; time of an event is atomic
GUT - INTEL 2015/16
Embedded Systems Software Engineering

3. Embedded Systems Software Engineering
Basic concepts (2)
action – an atomic operation execution; atomic in the current time scale
activity – operation executed by an object staying in some state until it is interrupted by an event
GUT - INTEL 2015/16
Embedded Systems Software Engineering

4. Embedded Systems Software Engineering
Basic concepts (3)
state transition – a relationship between two states of an object; the object in the first state will perform certain actions and enter the second state when a specified event occurs and specified conditions are satisfied
state machine – an abstract machine performing object state transitions on events; represented by state transition diagram
GUT - INTEL 2015/16
Embedded Systems Software Engineering

5. State transition diagram
event
state transition
Switch On ●
Off On
initial state
Shut down
state
Switch off ◉
final state
GUT - INTEL 2015/16
Embedded Systems Software Engineering

6. State transition signature
event [guard condition] / action expression
GUT - INTEL 2015/16
Embedded Systems Software Engineering

7. Embedded Systems Software Engineering
Event categories
Call event
Signal event
Change event
Time event
GUT - INTEL 2015/16
Embedded Systems Software Engineering

8. Call event operation name (parameter list)
An event occurring when an operation should be performed
operation name (parameter list)
GUT - INTEL 2015/16
Embedded Systems Software Engineering

9. Embedded Systems Software Engineering
Signal event
«signal»
Mouse
pos: Point
«signal»
«signal»
«signal»
«signal»
MouseDown
MouseUp
MouseMove
MouseRoll
btn: Button
btn: Button
dist: Point
GUT - INTEL 2015/16
Embedded Systems Software Engineering

10. Change event An event occurring when some condition is satisfied
when condition expression
GUT - INTEL 2015/16
Embedded Systems Software Engineering

11. Embedded Systems Software Engineering
Time event
An event occurring:
after some time interval
after time expression
in some time moment
when time expression
GUT - INTEL 2015/16
Embedded Systems Software Engineering

12. Embedded Systems Software Engineering
Guard condition
Boolean expression containing:
triggered event parameters
object properties and states
when an object is in some state (in state name)
Guard condition is checked after triggering an event, and before firing a state transition
GUT - INTEL 2015/16
Embedded Systems Software Engineering

13. Embedded Systems Software Engineering
Action expression
A sequence of operation calls sequentially executed
Operations are separated with semicolons
Operations arguments can use triggered event parameters
GUT - INTEL 2015/16
Embedded Systems Software Engineering

14. Embedded Systems Software Engineering
Transition example
MouseDown (btn, loc) [loc in Window]
/ object := Window.FindObject (loc); object.Select ()
GUT - INTEL 2015/16
Embedded Systems Software Engineering

15. Embedded Systems Software Engineering
Entry & exit actions
Data maintenance
entry / connect to data base
exit / disconnect data base
do/ check unused records
include / internal state machine
get progress / display progress
GUT - INTEL 2015/16
Embedded Systems Software Engineering

16. Embedded Systems Software Engineering
Compound states
Sequential substates
Concurrent substates
GUT - INTEL 2015/16
Embedded Systems Software Engineering

17. Sequential and concurrent substates
Diagnostics
Diagnosing ● ◉
Diagnosing
Circuit 1
Pass
Diagnosing
Circuit 2
Pass ●
Passed
Fail
Fail ● ◉
Diagnosing
Circuit 3
Pass
Diagnosing
Circuit 4
Pass
Failed
Fail
Fail
GUT - INTEL 2015/16
Embedded Systems Software Engineering

18. Concurrent states synchronization
State A1
State A2
Initialization
Finalization
State B1
State B2
Synchronization bar
GUT - INTEL 2015/16
Embedded Systems Software Engineering

19. Embedded Systems Software Engineering
Activity diagram
A special state transition diagram when:
state nodes represent actions or sub-activities
state transitions are fired just after the preceding activities are finished
GUT - INTEL 2015/16
Embedded Systems Software Engineering

20. Activity diagram example
[operation = get balance] ●
Authorization
Choose operation
Display balance
[operation = withdraw]
[operation = exit]
Entering
amount ◉
Check balance
[balance positive]
[balance negative]
Counting money
Preparing
check
Taking money
GUT - INTEL 2015/16
Embedded Systems Software Engineering

21. Concurrent activities
Object 1
Object 2
Object 3
Initialization
Activity A1
Activity B1
Activity C1
Activity A2
Activity C2
Finalization
“swimlines"
GUT - INTEL 2015/16
Embedded Systems Software Engineering

22. Embedded Systems Software Engineering
Bibliography
Grady Booch, James Rumbaugh, Ivar Jacobson: Unified Modeling User Guide (book, PDF)
GUT - INTEL 2015/16
Embedded Systems Software Engineering