Object-Oriented Modeling Using UML (2)

Object-Oriented ModelingUsing UML (2) CS 3331 Fall 2009

Outline • Modeling dynamic behavior • Statechart diagram • Sequence diagram • Modeling requirements • Use case diagram

Modeling Dynamic Behavior • Statechart diagram • Depicts the flow of control using states and transitions • Generalization of finite state machines • Sequence diagram • Depicts object interaction by highlighting the time ordering of method invocations

On Off Statechart Diagram • Graph representing finite state machine • Network of states and transitions • Good for modeling reactive systems push switch push switch

Elements of Statechart Final State Initial State Transition Running Idle State

State • Condition or situation in the life of a system (or object) during which it: • Satisfies some condition, • Performs some activity, or • Waits for some events. • Set of values of properties that affect the behavior of the system (or object). • Determines response to an event, • Thus, different states may produce different responses to the same event

Transition • Relationship between two states indicating that a system (or object) in the first state will: • Perform certain actions and • Enter the second state when specified event occurs and specified condition is satisfied. • Consists of: • Source and target states • Optional event, guard condition, and action Event [Condition] / Action Target Source

Definition • Event • An occurrence of a stimulus that can trigger a state transition • Instantaneous and no duration • Action • An executable atomic computation that results in a change in state of the model or the return of a value

Example dial digit(n) [incomplete] Ringing connected Connecting Dialing dial digit(n) [valid] / connect dial digit(n) [invalid] busy Busy Invalid

Another Example recovery success recovery failure Recovery Identification anomaly Normal temperature pressure recovery failure Pressure Recovery Temperature Recovery recovery success recovery failure recovery success

Composite States Recovery anomaly Recovery Identification Normal recovery success temperature pressure Pressure Recovery Temperature Recovery recovery failure

Composite States (Cont.) • Used to simplify diagrams • Inside, looks like statechart • May have composite transitions • May have transitions from substates • Sequential and parallel

Composites and Transitions Transition to/from composite state Active Idle Validating Processing Selecting Maintenance Printing Transition from substate

Start entry / start dial tone exit / end dial tone Dial Number Include / Dialing Partial Dialing entry / number.append(n) Including Composite States Dialing [number.isValid()] digit(n) digit(n)

Superstate substate1 substate2 substate3 substate4 Parallel Composition • Concurrency (split of control) • Synchronization

Example Incomplete HW1 HW2 Passed Project fail Midterm Final Failed

Group Exercise: Cellular Phone • Draw a statechart describing the operation of a cellular phone. Assume that the cellular phone has keys for: • power on and off • keypad locking and unlocking • 0-9, #, and * • talk (or send) and end Model at least the following operations: • power on/off • keypad locking/unlocking • making calls (e.g., dialing, connecting, talking), • receiving calls (e.g., ringing, talking)

Sequence Diagram • Describes a sequence of method calls among objects • Highlights the time ordering of method calls

object control lifetime message Example

Sequence of message sending Example (Cont.)

object link message Collaboration Diagram

Collaboration Collaboration Diagram

Modeling Requirements • Use case diagram • Describes the externally observable behavior of system functions, usually to define system requirements • Describes interactions between the system and external entities

Check Grades Validate User Register Student Example: Goldmine system boundary use case actor <<include>>

Elements of Use Case Diagram • Actor: • represents a role played by external entities that interact with the system • Use case: • Describes what the system does (i.e., functionality) • Scenario: sequence of interactions between the actors and the system • Relationship: • Extension (or generalization) among actors • Association between actors and use cases • Dependency among use cases: include and extend

Student Faculty User Student Faculty User Enter Grades Validate User Check Grades Get Roster Register Example: Goldmine (Cont.) <<include>> <<include>> <<extend>>

Use Case: Check Grades Description: View the grades of a specific year and semester Actors: Student Precondition: The student is already registered Main scenario: User System 1. The system carries out “Validate User”, e.g., for user “miner” with password “allAs”. 2. The system prompts for the year and semester. 4. The system displays the grades of the courses taken in the given semester, i.e., Fall 2007. 3. The user enters the year and semester, e.g., Fall 2007. Alternative: The student enters “All” for the year and semester, and the system displays grades of all courses taken so far. Exceptional: The “Validate User” use case fails; the system repeats the validation use case. Use Case Scenarios

Group Exercise: E-book Store Identify the main actors and the key use cases for an e-bookstore, and draw a use case diagram. Describe the use case scenario for the most important use case. The core requirements of the e-bookstore are to allow its customers to browse and order books, music CDs, and computer software through the Internet. The main functionalities of the system are to provide information about the titles it carries to help customers make purchasing decisions; handle customer registration, order processing, and shipping; and support management of the system, such as adding, deleting, and updating titles and customer information.

Object-Oriented Modeling Using UML (2)