Modeling Behavior

1. Modeling Behavior Interaction Diagrams Activity Diagram State Machine Diagram OOAD

2. Learning Objectives Understand how to represent system logic with interaction diagrams. Understand how to represent system logic with activity diagram. Understand how to represent system logic with state machine diagram. Chapter 8 Appendix © 2008 by Prentice Hall 2

3. UML Dynamic Modeling • In all systems, events happen dynamically, e.g.: • Objects are created and destroyed • Objects send messages to one another • External events trigger operations on certain objects • Objects have states that would be difficult to capture in a static model OOAD

4. UML Dynamic Modeling (cont.) • Behavior diagrams (dynamic): • Interaction diagrams • Sequence diagrams • Collaboration diagrams • Statechart diagrams • Activity diagrams OOAD

5. Sequence Diagrams: An example OOAD

6. Collaboration diagram: An Example OOAD

7. When to use Interaction Diagrams? • Interaction diagrams are used when you want to model the behavior of several objects in a use case.  They demonstrate how the objects collaborate for the behavior.  • Interaction diagrams do not give a in depth representation of the behavior.  If you want to see what a specific object is doing for several use cases use a state diagram.  To see a particular behavior over many use cases or threads use an activity diagrams. OOAD

8. Messages are passed between objects, and may contain parameters (e.g., message name (parameter list))

9. Sequence Diagrams • Describing the behavior of a system by viewing the interaction between the system and its environment • Shows the objects participating in the interaction by their life lines and the messages they exchange • Shows an interaction arranged in a time sequence OOAD

10. Elements of a sequence diagram • Objects: represented by boxes at top of diagram. • Lifeline: the time during which an object exists. • Messages: means by which objects communicate with each other. • Activation: the time period during which an object performs an operation. OOAD

11. Objects/Classes ATMMachine SavingAccount Client Insert ATM card Request PIN Enter PIN code Verify PIN code PIN valid activation Request amount Enter amount Process transaction Transaction successful Dispense cash Print receipt lifeline

12. Collaboration Diagrams • Also known as Communication diagrams • Represents a collaboration, which is a set of objects related in a particular context, and interaction, which is a set of messages exchanged among the objects within the collaboration to achieve a desired outcome • sequences of messages are shown by numbering OOAD

13. 1: insert ATM card 3: enter PIN code 7: enter amount :ATMMachine :Client 2: request PIN 6: request amount 10: dispense cash 11: print receipt 4: verify PIN code 8: process transaction 5: valid PIN code 9: transaction successful :SavingAccount

14. Sequence Vs Collaboration • Sequence Diagram: • Dynamic behavior of a set of objects arranged in time sequence, new objects added to the right • Good for real-time specifications and complex scenarios • easier to read • Collaboration Diagram : • Shows the relationship among objects. • Does not show time • Objects are arranged in a graph or network format • Both are used to examine the behavior of objects within a single use case OOAD

15. How to draw sequence diagram?

16. Drawing Sequence Diagrams • Determine the context of the sequence diagram • Identify the object that are participate in the sequence • Set of the lifeline for each object • Lay out of messages from the top to the bottom of the diagram based on the order in which they sent • Add the execution occurrence to each object’s lifeline • Validate the sequence diagram

17. Identifying Classes/Objects • Noun phrase approach – read through the requirements or use cases looking for noun phrases • Some classes are implicit or taken from general knowledge • Carefully choose and define class names OOAD

18. Use Case: Withdraw saving A customer wants to draw money from his bank account. He enters his card into an ATM (automated teller machine). The ATM machine prompts “ Enter PIN”. The customer enters his PIN. The ATM (internally) retrieves the bank account number from the card. The ATM encrypts the PIN and the account number and sends it over to the bank. The bank verifies the encrypted account and PIN number. If the PIN number is correct, the ATM displays, “Enter Amount”. Draws money from the bank account and pays out the amount. OOAD

19. Use Case: Withdraw saving • Use Case: Withdraw Saving • Actors: Bank Client • Flow of Events: • Bank client insert ATM card into ATM machine • ATM machine request PIN code • Bank client enter PIN code • Verify PIN code entered with saving account • ATM machine request amount if the PIN is valid • Bank client enter the required amount • Process the transaction in the client account • ATM machine dispense cash • ATM machine print receipt when the transaction completed • Alternative Flow of Events • Invalid PIN code entered. Indicate error message. Return step 3. OOAD

20. Identifying Classes – noun phrase approach (example) • ATM System • Bank Client • ATM Card • ATM Machine • Savings Account • Cash • Message OOAD

21. ATMMachine SavingAccount Client Insert ATM card Request PIN Enter PIN code Verify PIN code PIN valid Request amount Enter amount Process transaction Transaction successful Dispense cash Print receipt

22. Another example … OOAD

23. ATM System ATM approval Deposit amount Client Withdraw amount • Use case: ATM approval • Insert ATM card • Request PIN • Enter PIN • Verify PIN • Display message to client

24. Client ATM Machine ClientDatabase • Use case: ATM approval • Insert ATM card • Request PIN • Enter PIN • Verify PIN • Display message to client

28. ATM System ATM approval Deposit amount Client Withdraw amount • Use case: Withdraw amount • Request withdrawal amount • Enter withdrawal amount • Check account • Verify sufficient funds • Eject cash

29. Object naming • Syntax: [objectName]:[className] • Include object (instance) names when objects are referred to in messages or when several objects of the same type exist in the diagram • Name classes consistently with your class diagram Object B: Class B Object A: Class A :User messageA() messageB(“string”) messageC()

30. Stereotypes of Analysis Classes • Classes or objects can be classified into one of the following three stereotypes: • Entity – to hold data • Boundary – used by actors to interact with the system • For example: Customer place order, interact using a order form. • Control – coordinating behavior in the system • For example: control the activities in the transaction (i.e., rules, calculations)

31. Stereotypes of Analysis Classes Is an object relation that is extended to include responsibilities

32. Stereotypes of Analysis Classes Is an object relation that is extended to include responsibilities

33. Stereotypes of Analysis Classes A boundary class provides the interface between an actor and use case. The actor can be a human or an external system. Encapsulates connections between actors and use cases

34. Stereotypes of Analysis Classes A boundary class provides the interface between an actor and use case. The actor can be a human or an external system. Encapsulates connections between actors and use cases

35. Stereotypes of Analysis Classes A control class coordinates the tasks and captures the main logic in a use case. Mostly performs behaviors associated with inner workings of use cases

36. Typically, actors interact with boundary classes, which in turn interact with control classes, which in turn interact with entity classes.

39. Operations (behaviors) are depicted in the lower third of a class box. Operations fulfill the class’s responsibilities.

40. Modeling Behavior Activity Diagram State Diagram OOAD

41. Activity Diagram: An example OOAD

42. When to use Activity Diagram? • The main reason to use activity diagrams is to model the workflow behind the system being designed.  • Activity Diagrams are also useful for: analyzing a use case by describing what actions need to take place and when they should occur;  describing a complicated sequential algorithm;  and modeling applications with parallel processes. OOAD

43. Activity Diagram • Focus on flow of activity of internal process in object • similar to flowchart • describe changes in activity in a procedure • information from use case scenario or event flow can be used to describe activity diagram. • Used to provide detail for complex algorithms OOAD

44. Activity Diagram (cont.) • Purpose: • Modeling human task • Describe system’s function • Describe logic operation • Elements in activity diagram: Activity Transition Decision OOAD

45. Example of Activity Diagram for Register Course start Fill form Select course [No] Submit to PA approve? [Yes] Register course end

46. Example of Activity Diagram for ATM Authorization Read card Enter card Request PIN Enter PIN [No] Verify PIN valid? [Yes] Select other service

47. Swimlane • partition an activity diagram so that parts in the swimlane relevant to that activities in the partition • helpful in investigating responsibilities for interactions and associations between objects and actors OOAD

49. Activity diagram with synchronization bars – split into multiple paths and multiple paths combined into a single transition Top synchronization bar is a fork. Bottom synchronization bar is a join. OOAD

50. OOAD