UML The Unified Modeling Language A Practical Introduction Al-Ayham Saleh Aleppo University

UML Modeling A model is an abstraction of a situation Models consist of objects Objects are alive: –They know their attributes –They can do things using their methods –They exist in different states –Each object is unique, it is not any other object. Objects live in communities –they exchange messages –They have relationships with each other Objects live in a world, and there are other worlds Classes are blueprints of objects Object are instances of classes

UML Diagrams Use Case diagrams Class diagrams Object diagrams Sequence diagrams Collaboration diagrams State chart diagrams Activity diagrams Component diagrams Deployment diagrams

Class Diagrams Classes are representations of objects. Class diagrams represent Objects and their relations with each other. Class diagrams are static, they display WHO operates, not WHAT happens

Class Diagram Notations Class Name Attributes Properties Operations Methods Private Static Public Parameters Return Values

Information/Property Notations > opt visibility opt name multiplicity opt : type opt = initial-value opt {property-string} opt Example: Tagged value e.g. Author = Kari E.g. > - (private) only the class can see this attribute # (protected) only the class and all of its subclasses + (public) all classes that can see the class can also see the attribute Example: [1..*] :String Indicating one or more addresses. If no is present you will still have a the empty string (””). If [0..*] : String is specified, the can be null.

Operation/Method Notations > opt visibility opt name(parameter-list) multiplicity opt : return-type opt {property-string} opt Without polymorphism, a method is the same as an operation With polymorphism, an operation is represented by two or more methods

Class relationships Generalization Base sub Class2Class1Class2Class1 Association Dependency

Generalization superclass subclass generalization arrow Also called generalization/specialization Generalization is converted into inheritance when generating application code. Payment Cash General Special

Association Represents links between classes. –Customer makes a payment. –Customer makes an order. UML allows non-directional associations at the analysis phase Class2Class1

Association Associations have a navigational direction –A Customer’s Payment –Payment of a customer Navigational direction is a design issue, not an analysis issue. If no navigation is given, this may indicate a bidirectional navigation or that it is not specified. PaymentCustomer Payment

Association We have –ordinary association –simple aggregation: very similar to ordinary association, only means one class is more Important than the other. Aggregation is modeled by an empty diamond at the important part For the programmers, Aggregation is “Call by reference” –composition (strong aggregation)

Association We have –ordinary association –simple aggregation: –composition (strong aggregation) Composition is a Whole-Part relationship Composition is modeled by a black diamond at the Whole. Order can not exist outside the Customer For the programmers, Composition is “Call by value”

Association Associations have Multiplicity –0 –0.. 1 –0.. n –1 –1.. n –n

Association Associations have Roles –Roles explain the meaning of the association –Roles are “names” for the participation of each class in the association. –The programmer converts the roles to the appropriate property names. –Roles have visibility

Association Associations can be qualified –The association may have some internal parameters. –The designer should fully explain how the qualified association should be implemented.

Association Classes Associations can have properties and methods. An Association Class is a class that represents the association. InstitutePerson works for Job description salary

Reflexive Association

Designing with Associations UML designer should explain with maximum detail all the elements of an association Class A Class B Name and Visibility Of Role B Association Association Name Name of Role A Multiplicity of Role A Multiplicity of Role B

Dependency Dependency means “One class uses the other” Could be used to show that one method of a class uses some objects of the other class. Programmers use Dependency to include the definition of a class in the other. Basic Class Dependent Class Depends on

Abstract Classes Italic Means abstract Generalization means inheritance

Interfaces Interfaces are pure virtual classes Interfaces contain only declarations Interfaces can be realized by classes Interface inheritance is a good programming methodology. Realization

Parameterized classes Some classes may not be very clear by their own, but rather depend on an external parameter. Parameterized classes must be instantiated before you can create objects of them. You can understand parameterized classes as “class templates”

Designing effective class diagrams Organize similar classes into packages Beware of cyclical generalization Generalization and realization is unique between 2 classes Use associations where there are structural relationships Associations are NOT communication pipes. Start with Analysis, then refine details to the maximum level. Explain everything to the programmer using UML notations.

Common Class diagram pitfalls Cyclic generalization Redundant generalization Redundant realization UML/OOP features not supported in the implementation language –Multiple inheritance not supported by Java. Duplicate navigable roles for a class in many associations

Class diagrams in Rational Rose The class diagram toolbar Class Interface Association Association Class Package Dependency Generalization Realization

Class diagrams in Rational Rose Classes in Rational Rose

Class diagrams in Rational Rose Classes in Rational Rose

Class diagrams in Rational Rose Classes in Rational Rose

Class diagrams in Rational Rose Associations in Rational Rose

Quiz I Every student will be advised by one teacher. Some teachers advise many students, and some advise none. Which of the following class diagrams most clearly represents that student-teacher relationship?

Quiz 2 An application has many windows, each window has an icon, icons are stored in the application, and are shared between windows. An application has many windows, each window has a unique icon, icons are stored in the application, not in the windows. An application has many windows, each window has an icon, icons are stored in the windows, and referenced by the application. An application has many windows, each window is identified by its own unique icon. The application includes the windows and their icons.

Workshop Analyze the following business case using UML and Rational Rose, and design a class diagram for an OOP computer system that serves it. –A Customer makes an Order, and a Payment for it. –A Payment is one of three kinds: Cash, Check, or Credit. –The order contains Items, each item is bought in a specific quantity and at a specific price. –The Order can be in a STATE like: “pending” for new orders “approved” for received and accepted orders “rejected” for received and rejected orders “shipped” for approved orders that are shipped to the customer “closed” for orders received by the customer Duration 90 minutes