Using UML Patterns and Java ObjectOriented Software Engineering

Using UML, Patterns, and Java Object-Oriented Software Engineering Chapter 2, Modeling with UML

Application and Solution Domain ¨ Application Domain (Requirements Analysis): w The environment in which the system is operating ¨ Solution Domain (System Design, Object Design): w The available technologies to build the system Application Domain Model UML Package Traffic. Control Aircraft Summary. Display Traffic. Controller Flight. Plan Solution Domain System Model Airport Map. Display Flight. Plan. Database Traffic. Control Is the “system” part of the Domain or (part of) the Solution? Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 2

What is UML? ¨ UML (Unified Modeling Language) w An emerging standard for modeling object-oriented software. w Resulted from the convergence of notations from three leading object-oriented methods: t t t ¨ ¨ OMT (James Rumbaugh) OOSE (Ivar Jacobson) Booch (Grady Booch) Reference: “The Unified Modeling Language User Guide”, Addison Wesley, 1999. Supported by several CASE tools w Rational ROSE w Together. J Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 3

UML: First Pass ¨ You can model 80% of most problems by using about 20 % UML We teach you those 20% ¨ Use case Diagrams ¨ What system? w Describe the functional behavior of the system as seen by the user. ¨ Class diagrams Are class diagrams of this sort about requirements or design? w Describe the static structure of the system: Objects, Attributes, Associations ¨ Sequence diagrams Are sequence diagrams of this sort about requirements or design? w Describe the dynamic behavior between actors and the system and between objects of the system ¨ Statechart diagrams Are State. Charts of this sort about requirements or design? w Describe the dynamic behavior of an individual object (essentially a finite state automaton) ¨ Activity Diagrams Are activity diagrams of this sort about requirements or design? w Model the dynamic behavior of a system, in particular the workflow (essentially a flowchart) Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java Collaboration, Object, Component, Deployment diagrams in UML 1. x 4

UML Core Conventions ¨ ¨ ¨ Rectangles are classes or instances Ovals are functions or use cases states Instances are denoted with an underlined names w my. Watch: Simple. Watch w Joe: Firefighter ¨ Types are denoted with non underlined names w Simple. Watch w Firefighter ¨ Diagrams are graphs w Nodes are entities w Arcs are relationships between entities Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 5

Use Case Diagrams ¨ Used during requirements elicitation to represent external behavior Actors represent roles, that is, a type of user of the system Passenger ¨ Use cases represent a sequence of interaction for a type of functionality ¨ The use case model is the set of all use cases. It is a complete description of the functionality of Purchase. Ticket the system and its environment ¨ What would the functionality of the environment mean? Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 6

Actors ¨ An actor models an external entity which communicates with the system: w User w External system w Physical environment Passenger ¨ ¨ An actor has a unique name and an optional description. Examples: w Passenger: A person in the train w GPS satellite: Provides the system with GPS coordinates course project? Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 7

Use Case A use case represents a class of functionality provided by the system as an event flow. A use case consists of: Purchase. Ticket ¨ Unique name ¨ Participating actors ¨ Entry conditions ¨ Flow of events ¨ Exit conditions ¨ Special requirements Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 8

Use Case Diagram: Example Name: Purchase ticket Participating actor: Passenger Entry condition: ¨ Passenger standing in front of ticket distributor. ¨ Passenger has sufficient money to purchase ticket. Event flow: 1. Passenger selects the number of zones to be traveled. 2. �Distributor displays the amo due. 3. Passenger inserts money, of at least the amount due. 4. Distributor returns change. 5. Distributor issues ticket. Exit condition: ¨ Passenger has ticket. ¨ ¨ ¨ Use case diagrams represent external behavior Use case descriptions provide meat of model, not the use case diagrams. All use cases need to be described for the model to be useful. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 9

Class Diagrams = OO? Tarif. Schedule Enumeration get. Zones() Price get. Price(Zone) ¨ ¨ * * Trip zone: Zone Price: Price Class diagrams represent the structure of the system. Used w during requirements analysis to model problem domain concepts w during system design to model subsystems and interfaces w during object design to model classes. Is this from user’s point of view? Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 10

Classes Name Tarif. Schedule zone 2 price get. Zones() get. Price() ¨ ¨ ¨ Tarif. Schedule Table zone 2 price Enumeration get. Zones() Price get. Price(Zone) Attributes Operations Signature Tarif. Schedule A class represent a concept A class encapsulates state (attributes) and behavior (operations). Each attribute has a type. Each operation has a signature. The class name is the only mandatory information. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 11

Instances tarif_1974: Tarif. Schedule zone 2 price = { {‘ 1’, . 20}, {‘ 2’, . 40}, {‘ 3’, . 60}} ¨ ¨ ¨ An instance represents a phenomenon. The name of an instance is underlined and can contain the class of the instance. The attributes are represented with their values. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 12

Actor vs Instances ¨ ¨ What is the difference between an actor , a class and an instance? Actor: w An entity outside the system to be modeled, interacting with the system (“Passenger”) ¨ ¨ Class: w An abstraction modeling an entity in the problem domain, must be modeled inside the system (“User”) Would you agree? Object: w A specific instance of a class (“Joe, the passenger who is purchasing a ticket from the ticket distributor”). Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 13

Associations ¨ ¨ Tarif. Schedule Trip. Leg Enumeration get. Zones() Price get. Price(Zone) Price Zone * * Associations denote relationships between classes. The multiplicity of an association end denotes how many objects the source object can legitimately reference. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 14

1 -to-1, 1 -to-many, many-to-many Associations Point Country name: String Has-capital * Polygon City name: String Stock. Exchange * * One-to-many association Lists ticker. Symbol Bernd Bruegge & Allen H. Dutoit x: Integer y: Integer draw() One-to-one association * Company * ticker. Symbol 1 SX_ID Many-to-Many Associations Object-Oriented Software Engineering: Using UML, Patterns, and Java Company 15

Aggregation ¨ ¨ An aggregation is a special case of association denoting a “consists of” hierarchy. The aggregate is the parent class, the components are the children class. Exhaust system 1 0. . 2 1 Muffler Tailpipe diameter ¨ A solid diamond denotes composition, a strong form of aggregation where components cannot exist without the aggregate. (Bill of Material) Ticket. Machine 3 Zone. Button Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 16

Inheritance Button Cancel. Button ¨ ¨ Zone. Button The children classes inherit the attributes and operations of the parent class. What else? Inheritance simplifies the model by eliminating redundancy. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 17

Object Modeling in Practice: Class Identification: Name of Class, Attributes and Methods Foo Betrag Customer. Id Deposit() Withdraw() Get. Balance() Foo “Dada” Betrag Customer. Id Deposit() Withdraw() Get. Balance() Account Betrag Customer. Id Naming is important! Is Foo the right name? Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java Deposit() Withdraw() Get. Balance() 18

Object Modeling in Practice ctd Account Bank Name Betrag Account. Id Customer. Id Deposit() Withdraw() Get. Balance() Customer Name Customer. Id 1) Find New Objects 2) Iterate on Names, Attributes and Methods Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 19

Object Modeling in Practice: A Banking System Account Bank Name Betrag Account. Id Customer. Id Account. Id * Customer Has Deposit() Withdraw() Get. Balance() Name Customer. Id 1) Find New Objects 2) Iterate on Names, Attributes and Methods 3) Find Associations between Objects 4) Label the assocations 5) Determine the multiplicity of the assocations Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 20

Practice Object Modeling: Iterate, Categorize! Account Bank * Name What should these do? Savings Account Withdraw() Bernd Bruegge & Allen H. Dutoit Amount Account. Id Customer. Id Account. Id * Customer Has Deposit() Withdraw() Get. Balance() Name Customer. Id() Checking Account Mortgage Account Withdraw() Object-Oriented Software Engineering: Using UML, Patterns, and Java 21

Packages ¨ ¨ A package is a UML mechanism for organizing elements into groups (usually not an application domain concept) Packages are the basic grouping construct with which you may organize UML models to increase their readability. Dispatcher. Interface Notification ¨ Incident. Management A complex system can be decomposed into subsystems, where each subsystem is modeled as a package Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 22

UML sequence diagrams ¨ Passenger w To refine use case descriptions w to find additional objects (“participating objects”) Ticket. Machine ¨ select. Zone() Used during requirements analysis Used during system design w to refine subsystem interfaces ¨ ¨ ¨ insert. Coins() ¨ Classes are represented by columns Messages are represented by arrows Activations are represented by narrow rectangles Lifelines are represented by dashed lines pickup. Change() pick. Up. Ticket() ¨ ¨ Bernd Bruegge & Allen H. Dutoit UML sequence diagram represent behavior in terms of interactions. Useful to find missing objects. Time consuming to build but worth the investment. Complement the class diagrams (which represent structure). Object-Oriented Software Engineering: Using UML, Patterns, and Java 23

Nested messages Passenger Zone. Button select. Zone() Tarif. Schedule Display lookup. Price(selection) price Dataflow display. Price(price) …to be continued. . . ¨ ¨ The source of an arrow indicates the activation which sent the message An activation is as long as all nested activations Horizontal dashed arrows indicate data flow Vertical dashed lines indicate lifelines Is this from user’s point of view? Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 24

Iteration & condition …continued from previous slide. . . Passenger Change. Processor *insert. Change(coin) Iteration Condition Coin. Identifier Display Coin. Drop lookup. Coin(coin) price display. Price(owed. Amount) [owed. Amount<0] return. Change(-owed. Amount) …to be continued. . . ¨ ¨ Iteration is denoted by a * preceding the message name Condition is denoted by boolean expression in [ ] before the message name Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 25

Creation and destruction …continued from previous slide. . . Passenger Change. Processor Creation create. Ticket(selection) Ticket print() free() ¨ ¨ ¨ Destruction Creation is denoted by a message arrow pointing to the object. Destruction is denoted by an X mark at the end of the destruction activation. In garbage collection environments, destruction can be used to denote the end of the useful life of an object. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 26

State Chart Diagrams State Initial state Event Transition Final state Bernd Bruegge & Allen H. Dutoit Represent behavior as states and transitions Object-Oriented Software Engineering: Using UML, Patterns, and Java 27

Activity Diagrams ¨ An activity diagram shows flow control within a system ¨ An activity diagram is a special case of a state chart diagram in which states are activities (“functions”) Two types of states: ¨ w Action state: t t Cannot be decomposed any further Happens “instantaneously” with respect to the level of abstraction used in the model w Activity state: t t Can be decomposed further The activity is modeled by another activity diagram Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 28

Statechart Diagram vs. Activity Diagram Statechart Diagram for Incident (similar to Mealy Automaton) (State: Attribute or Collection of Attributes of object of type Incident) Event causes State transition Active Inactive Incident. Handled Closed Incident. Documented Archived Incident. Archived Activity Diagram for Incident (similar to Moore (State: Operation or Collection of Operations) Completion of activity causes state transition Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java Triggerless Transition 29

Activity Diagram: Modeling Decisions Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 30

Activity Diagrams: Modeling Concurrency ¨ ¨ Synchronization of multiple activities Splitting the flow of control into multiple threads Splitting Bernd Bruegge & Allen H. Dutoit Synchronization Object-Oriented Software Engineering: Using UML, Patterns, and Java 31

Activity Diagrams: Swimlanes ¨ Actions may be grouped into swimlanes to denote the object or subsystem that implements the actions. Allocate Resources Open Incident Coordinate Resources Dispatcher Archive Incident Field. Officer Document Incident Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 32

UML Summary ¨ UML provides a wide variety of notations for representing many aspects of software development w Powerful, but complex language w Can be misused to generate unreadable models w Can be misunderstood when using too many exotic features ¨ For now we concentrate on a few notations: w Functional model: Use case diagram w Object model: class diagram w Dynamic model: sequence diagrams, statechart and activity diagrams Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 33

Appendix: Additional Slides Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 34

Overview: modeling with UML ¨ ¨ ¨ What is modeling? What is UML? Use case diagrams Class diagrams Self-reading in “Additional Slides” Sequence diagrams Activity diagrams Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 35

Self-reading What is modeling? ¨ ¨ Modeling consists of building an abstraction of reality. Abstractions are simplifications because: w They ignore irrelevant details and w They only represent the relevant details. ¨ What is relevant or irrelevant depends on the purpose of the model. Why model software? ¨ Software is getting increasingly more complex w Windows XP > 40 M lines of code w A single programmer cannot manage this amount of code in its entirety. ¨ ¨ Code is not easily understandable by developers who did not write it We need simpler representations for complex systems w Modeling is a means for dealing with complexity Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 36

Example: street map Self-reading 1. 2. 3. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java Abstraction Decomposition Hierarchy 37

Systems, Models and Views ¨ ¨ Self-reading A model is an abstraction describing a subset of a system A view depicts selected aspects of a model A notation is a set of graphical or textual rules for depicting views Views and models of a single system may overlap each other Examples: ¨ System: Aircraft ¨ Models: Flight simulator, scale model ¨ Views: All blueprints, electrical wiring, fuel system Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 38

Systems, Models and Views Self-reading Flightsimulator Blueprints Aircraft Scale Model Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java Electrical Wiring 39

Models, Views and Systems (UML) * System Self-reading * Model Described by Depicted by What does this rectangle mean? Airplane: System Scale Model: Model Blueprints: View Bernd Bruegge & Allen H. Dutoit View Flight Simulator: Model Fuel System: View Electrical Wiring: View Object-Oriented Software Engineering: Using UML, Patterns, and Java 40

Self-reading Concepts and Phenomena Phenomenon w An object in the world of a domain as you perceive it w Example: The lecture you are attending w Example: My black watch Concept w Describes the properties of phenomena that are common. w Example: Lectures on software engineering w Example: Black watches Concept is a 3 -tuple: loose w Name (To distinguish it from other concepts) w Purpose (Properties that determine if a phenomenon is a member of a concept) w Members (The set of phenomena which are part of the concept) Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 41

Concepts and phenomena Name Clock ¨ Self-reading Purpose Members A device that measures time. Abstraction w Classification of phenomena into concepts ¨ Modeling w Development of abstractions to answer specific questions about a set of phenomena while ignoring irrelevant details. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 42

Models for Plato’s and Aristotle’s Views of Reality Plato ¨ ¨ Aristotle Material reality is a second-class subordinate type of reality. The first-class type is a “form” Forms lie behind every thing or in the world. Forms can be abstract nouns like “beauty” or “mammal” or concrete nouns like “tree” or “horse”. There is an important difference between the world of forms and particulars. Forms are nonmaterial, particulars are material. Forms are permanent and changeless. Particulars are changing. Forms can be acquired intellectually through a “dialectic” process that moves toward the highest understanding of reality through the interaction of questions and answers. Aristotle accepted the reality of Forms as nonmaterial entities. ¨ However, he could not accept Plato’s idea, that these Forms were not real. ¨ Instead of two separate worlds, one for Forms and one for Particulars, Aristotle had only one world, a world of particular things. ¨ Particular things according to Aristotle have a certain permance about them, even while they are subject to change: A tree changes colors without ceasing to be a tree. A horse grows in size without ceasing to be a horse. ¨ What is the root of this permancence? It is the thing’s internal form, which minds detect, when they penetrate beyond the thing’s changing attributes. So for Aristotle, reality is thus made up of particular viewpoints things that are eacheasily composed of Using UML, we can illustrate Platon’s and Aristotle’s very form antdn matter. . and see their differences as well Bernd Bruegge & Allen H. Dutoit ¨ Object-Oriented Software Engineering: Using UML, Patterns, and Java 43

Model for Plato’s View of Reality ¨ ¨ Plato Material reality is a secondclass subordinate type of reality. The first-class type is a “form” Forms lie behind every thing or in the world. Forms can be abstract nouns like “beauty” or “mammal” or concrete nouns like “tree” or “horse”. There is an important difference between the world of forms and particulars. Forms are nonmaterial, particulars are material. Forms are permanent and changeless. Particulars are changing. Forms can be acquired intellectually through a “dialectic” process that moves toward the highest understanding of reality through Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java the interaction of questions and 44

Model Aristotle’s Views of Reality Aristotle ¨ ¨ ¨ Aristotle accepted the reality of Forms as nonmaterial entities. However, he could not accept Plato’s idea, that these Forms were not real. Instead of two separate worlds, one for Forms and one for Particulars, Aristotle had only one world, a world of particular things. Particular things according to Aristotle have a certain permance about them, even while they are subject to change: A tree changes colors without ceasing to be a tree. A horse grows in size without ceasing to be a horse. What is the root of this permancence? It is the thing’s internal form, which minds detect, when they penetrate beyond the thing’s changing attributes. So for Aristotle, reality is thus made up of particular things that are each Object-Oriented Software Engineering: Using UML, Patterns, and Java Bernd Bruegge & Allen H. Dutoit composed of form antdn matter. . 45

Comparison of Plato’s and Aristotle’s Views Aristotle Plato Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 46

The <<extends>> Relationship ¨ ¨ Passenger ¨ Purchase. Ticket ¨ <<extends>> Out. Of. Order represent exceptional or seldom invoked cases. The exceptional event flows are factored out of the main event flow for clarity. Use cases representing exceptional flows can extend more than one use case. The direction of a <<extends>> relationship is to the extended use case <<extends>> Cancel Bernd Bruegge & Allen H. Dutoit <<extends>> relationships Time. Out No. Change Object-Oriented Software Engineering: Using UML, Patterns, and Java 47

The <<includes>> Relationship ¨ Passenger ¨ Purchase. Multi. Card ¨ Purchase. Single. Ticket <<includes>> <<extends>> No. Change Bernd Bruegge & Allen H. Dutoit Collect. Money <<includes>> relationship represents behavior that is factored out of the use case. <<includes>> behavior is factored out for reuse, not because it is an exception. The direction of a <<includes>> relationship is to the using use case (unlike <<extends>> relationships). <<extends>> Cancel Object-Oriented Software Engineering: Using UML, Patterns, and Java 48

Concepts in software: Type and Instance ¨ Type: w An abstraction in the context of programming languages w Name: int, Purpose: integral number, Members: 0, -1, 1, 2, -2, . . . ¨ Instance: w Member of a specific type ¨ The type of a variable represents all possible instances the variable can take The following relationships are similar: w “type” <–> “instance” w “concept” <–> “phenomenon” Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 49

Abstract Data Types & Classes ¨ Abstract data type w Special type whose implementation is hidden from the rest of the system. ¨ Class: w An abstraction in the context of objectoriented languages ¨ Like an abstract data type, a class encapsulates both state (variables) and behavior (methods) w Class Vector ¨ Unlike abstract data types, classes can be defined in terms of other classes using inheritance Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 50

From Problem Statement To Object Model Is this a “problem”? Problem Statement: A stock exchange lists many companies. Each company is uniquely identified by a ticker symbol Class Diagram: Stock. Exchange * * Lists Company ticker. Symbol problem statement = requirement? = domain description? Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 51

From Problem Statement to Code Is this a “problem”? Problem Statement : A stock exchange lists many companies. Each company is identified by a ticker Symbol Class Diagram: Stock. Exchange * Lists * Company ticker. Symbol Java Code public class Stock. Exchange { private Vector m_Company = new Vector(); }; Where is the design, then? public class Company { public int m_ticker. Symbol; private Vector m_Stock. Exchange = new Vector(); }; Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 52

Qualifiers Without qualification Directory 1 * File filename With qualification Directory ¨ filename 1 0… 1 File Qualifiers can be used to reduce the multiplicity of an association. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 53

UML first pass: Use case diagrams Use case Package Watch Actor Read. Time Watch. User Set. Time Watch. Repair. Person Change. Battery Use case diagrams represent the functionality of the system from user’s point of view Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 54

UML first pass: Class diagrams represent the structure of the system Association Class Multiplicity Watch 1 2 Push. Button state push() release() Attribute 1 1 1 2 1 LCDDisplay blink. Idx blink. Seconds() blink. Minutes() blink. Hours() stop. Blinking() referesh() Battery load 1 Time now Operations Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 55

UML first pass: Sequence diagram Actor : Watch. User Message Object : Watch : LCDDisplay press. Button 1() blink. Hours() press. Button 1() blink. Minutes() press. Button 2() : Time increment. Minutes() refresh() press. Buttons 1 And 2() commit. New. Time() stop. Blinking() Activation Lifeline Sequence diagrams represent the behavior as interactions Is this from user’s point of view? Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 56

UML first pass: Statechart diagrams for objects with interesting dynamic behavior Event Initial state State Transition Final state Represent behavior as states and transitions Is this from user’s point of view? Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 57

Other UML Notations UML provide other notations that we will be introduced in subsequent lectures, as needed. ¨ Implementation diagrams w Component diagrams w Deployment diagrams w Introduced in lecture on System Design ¨ Object constraint language w Introduced in lecture on Object Design These are from UML 1. x Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 58

What should be done first? Coding or Modeling? ¨ It all depends…. ¨ Forward Engineering: w Creation of code from a model w Greenfield projects ¨ Reverse Engineering: w Creation of a model from code w Interface or reengineering projects ¨ Roundtrip Engineering: w Move constantly between forward and reverse engineering w Useful when requirements, technology and schedule are changing frequently Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 59