Building multitiers program Building multitiers program Week 9 Contents 1. Review OOP 2. Three-tier application 3. Implementing 3-tier Slide 2 Create class  Add new class: menu Project->Add Class  Create properties for a class  Create methods for a class  Create events for class Slide 3 Creating properties for a class  Declare all variables in a class as private (encapsulation)  private properties must be assigned values and can be get values  through get/set public dataType myProperty { get { return propertyName; } set { propertyName = value; } } Slide 4 Creating methods: Write constructors  A constructor is a special method that used to initialize the properties of the object  A constructor is invoked when the object gets instantiated  Note to write a constructor:  The name of the constructor and the name of the class are the same  A constructor does not return value, not even void  A class can have multiple constructors (overloaded constructors) public ClassName (parameterList) { } Instantiating an object  To instantiate an object, using the new keyword  Example: Lop l = new Lop(); Lop c; c = new Lop(“NCTH2K”, “Cao dang nghe 2K”); Slide 6 ClassName object = new ClassName (…); ClassName object; object = new ClassName (…); Using properties, methods of a class  Call methods or properties of a class  Using dot operator  Get/set methods:  get: variable = object.propertyName  set: object.propertyName = variable  Example: SinhVien sv = new SinhVien(); sv.HoTen = “Nguyen Van An”; sv.DiemLT = 5; sv.DiemTH = 10; lblTB.Text = sv.DiemTB().ToString(); MessageBox.Show(sv.HoTen + “ có ĐTB = ” + sv.DiemTB()); Slide 7 Contents 1. Review OOP 2. Three-tier application 3. Implementing 3-tier Slide 8 2. Three-tier application 2.1 What is a 3-tier architecture? 2.2 What is the need for dividing the code in 3-tiers? 2.3 Designing 3-tier Slide 9 2.1 What is a 3-tier architecture?  Three-tier (layer) is a client-server architecture in which the user interface , business rules and data access are developed and maintained as independent modules  There are:  Tier 1: Presentation tier  Tier 2: Business Logic tier  Tier 3: Data Access tier Slide 10 . Building multitiers program Building multitiers program Week 9 Contents 1. Review OOP 2. Three-tier