02291: System Integration UML State Machines Hubert Baumeister - PowerPoint PPT Presentation

02291: System Integration UML State Machines Hubert Baumeister huba@dtu.dk DTU Compute Technical University of Denmark Spring 2020

UML diagrams Wikipedia

Example ◮ Task: Implement a control panel for a safe in a dungeon ◮ The safe should be visible only when a candle has been removed ◮ The safe door opens only when the key is turned after the candle has been replaced again ◮ If the key is turned without replacing the candle, a killer rabbit is released SecurePanelController Safe doorClosed : bool open : bool candleIn : bool open candleRemoved() close keyTurned() closeSafe() -revealLock() -releaseKillerRabbit()

Example

Example Execution (Secret Panel Controller)

Example Execution (Safe)

Example Execution (Secret Panel Controler)

Example Execution (Safe)

Example Execution (Secret Panel Controler)

States 1

States 2

Transitions trigger [guard] / effect state state UML User Manual 2nd edition operation [guard] / action1; action2; ... state state

Example Transition Transition of the LSM for the SecretPanelController turnKey [candleIn] / safe.open() Lock Open SecretPanelController doorClosed : bool candleIn : bool ... candleRemoved() keyTurned() ... - releaseKillerRabbit() ... Transition of the LSM for the Safe safe 1 Safe open : boolean open() close() open Closed Open close

How to use State Machines ◮ In general: ◮ Focus on states and how a system reacts to events ◮ e.g. modal user interfaces ◮ e.g. hardware controller ◮ Model the life of an object → Life cycle state machine (LSM) → From the creation of the object to its destruction → Methods are events ◮ Model the allowed interaction between components ◮ Communication protocols → Protocol state machines (PSM)

Life cycle state machines SecurePanelController Safe doorClosed : bool open : bool candleIn : bool open candleRemoved() close keyTurned() closeSafe() -revealLock() -releaseKillerRabbit() closeSafe/safe.close() Open keyTurned[candleIn]/safe.open() open closed open close candleRemoved[doorClosed]/this.revealLock Wait Lock

Life cycle state machine (LSM)

Life cycle state machine: Possible implementation public class SecretPanelController { enum states { wait, lock, open, finalState }; states state = states.wait; public void candleRemoved() { switch (state) { case wait: if (doorClosed()) { state = states.lock; break; } } } public void keyTurned() { switch (state) { case lock: if (candleIn()) { state = states.open; safe.open(); } else { state = states.finalState; releaseRabbit(); } break; } } ... }

Life Cycle State Machine of a counter Initial state c = 0 and all the time c ≥ 0 Counter c : int public Counter() { c = 0;} inc public void inc() { c++; } dec public void dec() { if (c > 0) { c--; ]}

Nonorthogonal sub states

Sub states II: Leaving sub states

Orthogonal Sub states

History states

Activity diagrams compared with State machines Activity diagram

Activity diagrams compared with State Machine Activity Diagram State Machine