Using UML Patterns and Java ObjectOriented Software Engineering

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

Overview: modeling with UML ¨ What is modeling? ¨ What is UML? ¨ Use case diagrams ¨ Class diagrams ¨ State chart diagrams ¨ Interaction diagrams w Sequence diagrams ¨ Activity Functional Model Object Model Dynamic Model diagrams Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 2

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. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 3

Example: street map Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 4

Why model software? ¨ Software is getting increasingly more complex w Windows XP > 40 millions 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 mean for dealing with complexity Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 5

Systems, Models and Views 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 6

Systems, Models and Views Flightsimulator Blueprints Aircraft Model 2 View 1 System View 3 Model 1 Scale Model Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java Electrical Wiring 7

Models, Views and Systems (UML) * System * Model View Depicted by Described by Airplane: System Scale Model: Model Blueprints: View Bernd Bruegge & Allen H. Dutoit Flight Simulator: Model Fuel System: View Electrical Wiring: View Object-Oriented Software Engineering: Using UML, Patterns, and Java 8

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 watch Concept w Describes the properties of phenomena that are common. w Example: Lectures on software engineering w Example: Blue watches Concept is a 3 -tuple: 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 9

Concepts and phenomena Name Clock ¨ 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 10

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 11

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 object-oriented 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 12

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 Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 13

Object-oriented modeling Application Domain Model UML Package Traffic. Control Aircraft Bernd Bruegge & Allen H. Dutoit Summary. Display Traffic. Controller Flight. Plan Solution Domain System Model Airport Map. Display Flight. Plan. Database Traffic. Control Object-Oriented Software Engineering: Using UML, Patterns, and Java 14

What is UML? ¨ UML (Unified Modeling Language) w A standard for modeling object-oriented software. w Resulted from the convergence of notations from three leading object-oriented methods: t t t ¨ OMT (Object Modeling Technique - James Rumbaugh) OOSE (Object Oriented Software Engineering - Ivar Jacobson) Booch (Grady Booch) Supported by several CASE tools w w Rational ROSE Borland Together Argo. UML Argo. Eclipse Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 15

UML: First Pass ¨ You can model 80% of most problems by using about 20 % UML ¨ I’ll teach you those 20% and I hope that you learn those 20% Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 16

UML First Pass ¨ Use case Diagrams w Describe the functional behavior of the system as seen by the user. ¨ Class diagrams w Describe the static structure of the system: Objects, Attributes, Associations ¨ Sequence diagrams w Describe the dynamic behavior between actors and the system and between objects of the system ¨ Statechart diagrams w Describe the dynamic behavior of an individual object (essentially a finite state automaton) ¨ Activity Diagrams w Model the dynamic behavior of a system, in particular the workflow (essentially a flowchart) • Object. Diagrams • Component. Diagrams • Deployment. Diagrams • Collaboration. Diagrams Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 17

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 18

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 19

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 Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 20

UML first pass: Statechart diagrams for objects with interesting dynamic behavior Event Initial state State Transition Final state Bernd Bruegge & Allen H. Dutoit Represent behavior as states and transitions Object-Oriented Software Engineering: Using UML, Patterns, and Java 21

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 the lecture on System Design ¨ Object Constraint Language (OCL) w Introduced in lecture on Object Design Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 22

UML Core Conventions ¨ Rectangles are classes or instances ¨ Ovals are functions or use cases ¨ Instances are denoted with an underlined names w my. Watch: Simple. Watch w Joe: Firefighter ¨ Types are denoted w Simple. Watch w Firefighter ¨ Diagrams with non underlined names 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 23

Use Case Diagrams ¨ Used during requirements elicitation to represent external behavior ¨ Actors represent roles, that is, a type of user of the system 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 the system and its environment Passenger ¨ ¨ Purchase. Ticket Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 24

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 Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 25

Use Case ¨A use case represents a class of functionality provided by the system as an event flow. Purchase. Ticket Bernd Bruegge & Allen H. Dutoit ¨A use case consists of: w Unique name w Participating actors w Entry conditions w Flow of events w Exit conditions w Special (or Quality) requirements Object-Oriented Software Engineering: Using UML, Patterns, and Java 26

Use Case: Example Name: Purchase ticket Participating actor: Passenger Entry condition: ¨ Passenger standing in front of ticket distributor. ¨ Passenger has sufficient money to purchase ticket. Exit condition: ¨ Passenger has ticket. Event flow: 1. Passenger selects the number of zones to be traveled. 2. Distributor displays the amount due. 3. Passenger inserts money, of at least the amount due. 4. Distributor returns change. 5. Distributor issues ticket. Anything missing? Quality requirements and scenarios! Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 27

The <<extends>> Relationship ¨ Dashed arrows in UML are Dependencies ¨ Passenger ¨ Purchase. Ticket ¨ <<extends>> Out. Of. Order Bernd Bruegge & Allen H. Dutoit 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 <<extends>> relationships Time. Out w An extend relationship is an entry condition in the extending No. Change use case Object-Oriented Software Engineering: Using UML, Patterns, and Java 28

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). w An include relationship can be <<extends>> inserted either in the flow event or quality requirements of the corresponding use case Cancel Object-Oriented Software Engineering: Using UML, Patterns, and Java 29

The “inheritance” Relationship In a inheritance relationship a use case specializes another more general. ¨ Note <<extends>> and inheritance relationships are different. ¨ In <<extends>> each use Authenticate case describes a different with Card flow of events to accomplish a different task. ¨ An inheritance relationship is specified in the sections participating actor, entry conditions, and exit conditions of the corresponding use case. ¨ Authenticate with Password Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 30

Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 31

Use Case Diagrams: Summary ¨ Use case diagrams represent external behavior ¨ Use case diagrams are useful as an index into the use cases ¨ 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 32

Class Diagrams Tarif. Schedule Enumeration get. Zones() Price get. Price(Zone) ¨ Class * * Trip zone: Zone Price: Price 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. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 33

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 34

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 35

UML: Class and Instance Diagrams Inspector joe: Inspector mary: Inspector Class Diagram anonymous: Inspector Instance Diagram Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 36

Attributes and Values Inspector name: string age: integer joe: Inspector name = “Joe” age = 24 Bernd Bruegge & Allen H. Dutoit mary: Inspector name = “Mary” age = 18 Object-Oriented Software Engineering: Using UML, Patterns, and Java 37

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”) ¨ 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 38

Associations Tarif. Schedule Trip. Leg Enumeration get. Zones() Price get. Price(Zone) Price Zone ¨ ¨ * * Associations denote relationships between classes. The multiplicity of an association denotes how many objects the source object can legitimately reference. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 39

1 -to-1 and 1 -to-many Associations Has-capital Country name: String City name: String One-to-one association Polygon * Point x: Integer y: Integer draw() One-to-many association Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 40

Links and Associations ¨ ¨ Links and associations establish relationships among objects and classes. Link: w A connection between two object instances. A link is like a tuple. w A link is an instance of an association ¨ Association: w Basically a bidirectional mapping. w One-to-one, many-to-one, one-to-many, many-to-many. w An association describes a set of links like a class describes a set of objects. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 42

Class Diagram vs Instance Diagram Sticky. Note Workorder * schedule() x: Integer y: Integer z: Integer Example for a one-to-many association : Sticky : Work. Order x, y, z=(-1, 0, 5) : Sticky x, y, z=(1, 10, 1) : Sticky x, y, z=(10, 1, 2) Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 43

From Problem Statement To Object Model Problem Statement: A stock exchange lists many companies. Each company is uniquely identified by a ticker symbol Class Diagram: Stock. Exchange * Bernd Bruegge & Allen H. Dutoit * Lists Company ticker. Symbol Object-Oriented Software Engineering: Using UML, Patterns, and Java 44

From Problem Statement to Code Pr oblem 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(); }; 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 45

Do UML associations have direction? w An association between two classes is by default a bi-directional mapping. A t t B Class A can access class B and class B can access class A Both classes play the agent role. If you want to make A a client, and B a server, you can make the association unidirectional. The arrowhead points to the server role: Name Direction Name of association A accesses B Association Direction Class A ( the “client”) accesses class B (“the server”). B is also called navigable Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 46

Roles ¨ ¨ ¨ A role name is the name that uniquely identifies one end of an association. A role name is written next to the association line near the class that plays the role. When do you use role names? w Necessary for associations between two objects of the same class w Also useful to distinguish between two associations between the same pair of classes ¨ When do you not use role names? w If there is only a single association between a pair of distinct classes, the names of the classes serve as good role names Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 47

Example of Role Problem Statement : A person assumes the role of repairer with respect to another person, who assumes the role of inspector with respect to the first person. Person Creates Workorders * Person repairperson Creates Workorders * inspector Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 48

Roles in Associations ¨ Client Role: w An object that can operate upon other objects but that is never operated upon by other objects. ¨ Server Role: w An object that never operates upon other objects. It is only operated upon by other objects. ¨ Agent Role: w An object that can both operate upon other objects and be operated upon by other objects. An agent is usually created to do some work on behalf of an actor or another agent. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 49

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 50

Aggregation and composition ¨ ¨ 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 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 Bernd Bruegge & Allen H. Dutoit Zone. Button Object-Oriented Software Engineering: Using UML, Patterns, and Java 51

Inheritance Button Cancel. Button ¨ ¨ Zone. Button The children classes inherit the attributes and operations of the parent class. Inheritance simplifies the model by eliminating redundancy. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 52

Object Modeling in Practice: Class Identification Foo Betrag Customer. Id Deposit() Withdraw() Get. Balance() Class Identification: Name of Class, Attributes and Methods Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 53

Object Modeling in Practice: Encourage Brainstorming 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 Deposit() Withdraw() Get. Balance() Object-Oriented Software Engineering: Using UML, Patterns, and Java 54

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 55

Object Modeling in Practice: A Banking System Account Betrag Account. Id Customer. Id Account. I d Deposit() Withdraw() Get. Balance() Bank Name * Has Customer 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 56

Practice Object Modeling: Iterate, Categorize! Account Bank * Name Savings Account Withdraw() Bernd Bruegge & Allen H. Dutoit Amount Account. Id Customer. Id Account. I d Deposit() Withdraw() Get. Balance() Checking Account Withdraw() * Customer Has Name Customer. Id() Mortgage Account Withdraw() Object-Oriented Software Engineering: Using UML, Patterns, and Java 57

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 58

UML sequence diagrams ¨ Passenger Used during requirements analysis w To refine use case descriptions w to find additional objects (“participating objects”) Ticket. Machine select. Zone() ¨ Used during system design w to refine subsystem interfaces insert. Coins() ¨ ¨ pickup. Change() ¨ ¨ pick. Up. Ticket() Bernd Bruegge & Allen H. Dutoit Classes Instances are represented by columns Messages are represented by arrows Activations are represented by narrow rectangles Lifelines are represented by dashed lines Object-Oriented Software Engineering: Using UML, Patterns, and Java 59

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 Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 60

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 61

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 62

Sequence Diagram Summary ¨ ¨ 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). Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 63

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 64

Activity Diagrams ¨ An activity diagram shows flow of 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 65

Activity Diagram: Modeling Decisions Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 67

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 68

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 69

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 70

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: 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 71

Additional Slides Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 72

Models for Plato’s and Aristotle’s Views of Reality ¨ ¨ Plato 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 ¨ ¨ ¨ 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 permanence 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 permanence? 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 composed of form and matter. . Using UML, we can illustrate Plato’s and Aristotle’s viewpoints very easily and see their differences as well Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 73

Model for Plato’s View of Reality ¨ ¨ Plato 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. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 74

Model Aristotle’s Views of Reality ¨ ¨ ¨ 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 permanence 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 permanence? 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 composed of form and matter. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 75

Comparison of Plato’s and Aristotle’s Views Aristotle Plato Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 76