UML 2.0 Composite Structures and State Machines

Transcription

1 UML 2.0 Composite Structures and State Machines Version Foils by Ø. Haugen and B. Møller-Pedersen 12-Feb-05 INF2120 Prosjekt i modellering 1

2 Overview of the lecture A very small repetition class diagrams, sequence diagrams, use cases what do they convey? Composite structures of classes and collaborations ports State Machines (basics) what is an FSM a Finite State Machine? example of a finite state machine State Machines (advanced) encapsulation (exit and entry points) composite states and submachinestates 12-Feb-05 INF2120 Prosjekt i modellering 2

3 Example - ATM Domain statement An Automatic Teller Machine (ATM) is a system with mechanical as well as electronic parts. Its purpose is to provide a bank user with cash provided that the user can authenticate herself and she has adequate funds in her bank account. She authenticates herself by presenting a card to the ATM cardreader, and a personal identification number (PIN) through the ATM keyboard. The ATM is connected electronically and possibly through some kind of network to the bank such that the account status may be checked online. The ATM is refilled with cash notes regularly or when the number of specific notes is below some limit. The ATM may also provide foreign currency to the customer 12-Feb-05 INF2120 Prosjekt i modellering 3

4 Class Diagram (1) concepts potential objects User * * ATM * 1 Bank 1 * associations between concepts 1 * Card 1 1 myaccounts Account 12-Feb-05 INF2120 Prosjekt i modellering 4

5 Class Diagram (2)... but a given keyboard of a given ATM, can only be contained in that ATM ATM composition between concepts there may be keyboards in other things than ATMs CardReader Keyboard Screen CashDispenser 12-Feb-05 INF2120 Prosjekt i modellering 5

6 Use Case Diagram use case is formally a class, not a behavior ATM the subject the system to be made CashRepository Withdrawal «include» Authentication User «include» Bank Currency actor outside the subject 12-Feb-05 INF2120 Prosjekt i modellering 6

7 Interaction Diagram lifeline typed by a class referring to a part/property continuation sd Authenticate :User :ATM :Bank interaction use combined fragment ref loop(0,2) Cardid(cid) Idle EnterPIN PIN NOK msg("try again!") ref EnterPIN 12-Feb-05 INF2120 Prosjekt i modellering 7

8 Composite Structure Collaboration collaboration part BankContext :User [ ] :ATM [1..100] :Bank What is inside one such ATM object? connector 12-Feb-05 INF2120 Prosjekt i modellering 8

9 Composite structure class ATM part CardReader Keyboard Screen CashDispenser User-Reader :CardReader ATM port User-Screen :Screen :Controller ATM-bank User-Keyboard :Keyboard :CashDispenser connector User-Cash 12-Feb-05 INF2120 Prosjekt i modellering 9

10 Finite State Machines Finite State a finite number of states [here] a small number of named states a stable situation where the process awaits stimuli a state in a state machine represents the history of the execution Machine that only a stimulus (signal, message) triggers behavior the behavior consists of executing transitions may also have local data 12-Feb-05 INF2120 Prosjekt i modellering 10

11 EnterPIN state machine start transition <<statemachine>> EnterPIN n:integer PIN: integer local data initial (pseudo) state sm EnterPIN send(msg( Give PIN )); n=1; PIN=0 enterdigit [n=4]digit/pin=... send(code(cid,pin)) [n<4]digit/ n++; PIN= PIN+digit*10 (3-n) transition [guard] trigger / action nok nok waitok ok ok state simple exit point definition 12-Feb-05 INF2120 Prosjekt i modellering 11

12 Statemachine for the ATM exit point usage sm ATM /authn=0 Idle submachinestate usage CardId(cid) :EnterPIN /authn=0 ok :Service [authn<3]/ authn++; send(msg( Try again )) nok Withdrawal status :Withdrawal :Status simple state with entry clause [authn==3]/ authn=0 send(msg( illegal entry )); CardOut ok entry: send(card) cancelled cardtaken 12-Feb-05 INF2120 Prosjekt i modellering 12

13 Attributes of the ATM Statemachine is a Classifier (that is class-like): Attributes Operations (local actions) <<statemachine>> ATM authn:integer cid: integer sa: Amount aa: Amount authn number of tries cid card id sa selected amount aa available amount sendmoney(a:amount) 12-Feb-05 INF2120 Prosjekt i modellering 13

14 State machine Withdrawal sm Withdrawal :GetAmount cancelled cancelled send(checkaccount(sa)) again nok/ send(msg( Amount too large )) entry point usage VerifyTransaction ok/ sendmoney(sa); send(receit(sa)); ok 12-Feb-05 INF2120 Prosjekt i modellering 14

15 Simple GetAmount sm GetAmount Send(msg( select amount )) :SelectAmount cancel Send(msg( select another amount )) cancelled amount(sa); again final state definition entry point definition 12-Feb-05 INF2120 Prosjekt i modellering 15

16 And we repeat The Knoble game 12-Feb-05 INF2120 Prosjekt i modellering 16

17 The game A game administrator controls the game Invites the players The players make a draw like: The game administrator calculates the scores 12-Feb-05 INF2120 Prosjekt i modellering 17

18 Composite Structure: Knoble Game Machine 1 GameAdm PlayerAdm create LocAdm Player ff Env create 12-Feb-05 INF2120 Prosjekt i modellering 18

19 A simple State Machine Player disconnected Initial State ConnectDefault ConnectPlayer disconnect disconnect Chat Playing connecting connected Chat disconnect disconnect Scissor Paper Stone startplay / starttimer1 NoGame responsetimer2 / cancelplay/ PlayerSignal stoptimer1 Chat cancelplay / stoptimer1&2 Simple states Transitions: trigger / action or trigger ^send Play / PlayerSignal(Play) Signing signon/starttimer responsetimer1 / starttimer2 SignedOn Chat 12-Feb-05 INF2120 Prosjekt i modellering 19

20 Motivating Composite State / Substate machine Some transitions are more global than others When a television set is ON you may be in textual mode or in normal television mode When in textual mode, the digits have a different interpretation than they do in normal television mode when you turn OFF the set, it goes black regardless of whether it is in textual or television mode One achieves better overview more compact code, transitions need in lesser degree be duplicated potential reuse of composite states composite states are potential units for on-line replacement 12-Feb-05 INF2120 Prosjekt i modellering 20

21 Remaking the Knoble player state space Player disconnected disconnect-transition is equivalent from four states disconnect Chat ConnectDefault ConnectPlayer disconnect Playing connecting connected Chat disconnect disconnect Scissor Paper Stone startplay / starttimer1 NoGame responsetimer2 / cancelplay/ PlayerSignal stoptimer1 Chat cancelplay / stoptimer1&2 connected chat-transition is equivalent for these four states Play / PlayerSignal(Play) Signing signon/starttimer responsetimer1 / starttimer2 SignedOn Chat 12-Feb-05 INF2120 Prosjekt i modellering 21

22 Substate machine: Connected Connected H Chat Initiated in all states within the composite state, returning to History pseudo-state Playing default starting point of Connected signon/starttimer NoGame responsetimer2 / cancelplay/ PlayerSignal stoptimer1 Signing Scissor Paper Stone cancelplay / stoptimer1&2 Play / PlayerSignal(Play) startplay / starttimer1 SignedOn responsetimer1 / starttimer2 composite state just a state parenthesis 12-Feb-05 INF2120 Prosjekt i modellering 22

23 Main state space revisited Player one instantiation of the Connected submachine state disconnected ConnectDefault connecting ConnectPlayer connected disconnect :Connected 12-Feb-05 INF2120 Prosjekt i modellering 23

24 Another potential use of submachine states A state machine is well encapsulated entry and exit points its own data space its own state space A submachine state represent the usage of such a state machine it is content as long as the interface behavior is consistent with the encloser of the submachine state Can we change the definition of the statemachine of the submachine state? at compile-time (modeling-time) at runtime? 12-Feb-05 INF2120 Prosjekt i modellering 24

25 Changing the behavior during runtime (before) Player currentstate states Connected Timeout2 nogame Timeout2 Timout1 / notify player, start Timer2 signing SignOn / start Timer1 Scissors Paper Stone playing Timeout1 / notify player, start Timer2 Play / sign player on for a new game CancelPlay signedon StartPlay / Inform player to move, start Timer1 12-Feb-05 INF2120 Prosjekt i modellering 25

26 Changing behavior during runtime (after) Before behavior change After behavior change Player When the Player state machine enters the initial state of Connected it is transferred to the new state definition. Connected currentstate states Connected /*new*/ Timeout2 nog ame Timeout2 nogame Timout1 / notify player, start Timer2 signing SignOn / start Timer1 Play / sign pla yer on for a new game CancelPlay signedon Scissors Paper Stone playing Timeout1 / notify player, start Timer2 StartPlay / Inform player to move, start Timer1 SignOn / Computer signing on signedon StartPlay / Computer choosing move 12-Feb-05 INF2120 Prosjekt i modellering 26