Introduction to DOT NET

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Introduction to DOT NET

• Lecture 1

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Today Topics

• Microsoft.NET Framework
• VB.NET Introduction

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The .NET Framework

• Chapter 1

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What Really is .NET?

• Software Technology
• connecting
• People
• information
• systems
• devices

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What Really is .NET?

• Write Once

Connect Everywhere to Every Device
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What Really is .NET?
.NET Framework a structure or an environment
for framing problems and facilitating effective
decisions.
Application development
Build
Deploy
Run
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.NET Terms in 1-3-5

• A way to accelerate this one move to distributed
  computing.
• Three levels to make distributed computing
  happen, which are
• Everything is a Web service,
• Ability to aggregate and integrate Web services
• Ability to Deliver simple, compelling user
  experiences
• Five things to address .NET
• Developer Tools .NET framework and Visual Studio
  tools to make writing web service as simple and
  as easy as possible
• Servers set of .NET servers to aggregate and
  deliver web services
• .NET building block services
• Device Software
• User experiences

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The .NET Framework
Framework Services
VB
C
C
Visual Studio.NET
JScript

Common Type Specification
4.ASP.NET Web Services and Web Forms
WindowsForms
3. ADO.NET Data and XML
2. Base Class Library
1. Common Language Runtime
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The .NET Framework
VB
C
C
JScript

• The .NET languages C, VB.NET, C, J, Jscript,
  and etc.

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The .NET Framework
Common Type Specification

• Common Type Specification or Common Language
  Specification
• A subset of .Net supported types
• A set of guidelines to write languages that run
  under the CLR (Common Language Runtime).
• A complete list of rules for the CLS in the .NET
  Framework SDK documentation

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The .NET Framework

• ASP.NET the platform allowing web applications
  and Web Services to be programmed in any .NET
  language.

4.ASP.NET Web Services and Web Forms
WindowsForms
Framework Services
3. ADO.NET Data and XML

• ADO.NET the platform allowing any .NET language
  to do database programming

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The .NET Framework

• The .NET class library collection of pre-built
  functionalities. Sometimes organized into
  technology sets such as ADO.NET and Windows Forms

2. Base Class Library
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Based Class Library

• Collections of commonly used code providing
  general functions being accessed from any
  application.
• Namespaces Logical groups of code are
  organized called Libraries contain fundamental
  code structures and methods that allow you to
  communicate with the operating system software
  and other applications
• The code in libraries can be reused across
  applications

ADO.NET Data Class
Windows forms
Web Forms
XML
File I/O

Core system classes (threading,
serilazation, Reflection, collections, and so on)
The .Net Class Library

• The actual library of code is located in one or
  more dynamic link library files such as
  System.data.dll

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.NET Base Class Library
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.NET Base Classes (continued)
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The .NET Framework

• The Common Language Runtime (CLR) .NET runtime
  engine that executes all .NET programs. Also
  provides automatic memory management, security,
  optimization, and garbage collection. The .NET
  languages are compiled to the same intermediate
  language, known as MS Intermediate Language (MSIL
  or IL).

1. Common Language Runtime
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Common Language Runtime

• Each .NET language provides a compiler that
  supports the CLR.
• No more DLL hell IL programs store extra info
  (Metadata) about their classes and the
  components.
• CLR can load more than one version of a component
  at a time.
• CLR monitors memory, automatically removes unused
  objects with its garbage collection.

Compiler and Loader
Code verification and optimization
Memory management garbage collection
Code access security
(other managed code services
The Common Language Runtime
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Language compilation in .NET
Code in VB.NET
Code in C
Code in another .NET Language
VB.NET compiler (vbc.exe)
C compiler (csc.exe)
Appropriate compiler
MSIL code
Deep language integration all .NET languages are
compiled to MSIL (intermediate language).
CLR Just-in-time execution
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The .NET Framework

• Visual Studio .NET optional development tool
  containing a rich set of productivity and
  debugging features

Visual Studio.NET
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The .NET Languages

• Chapter 2 and 3

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The .NET Languages

• The .NET framework ships with three code
  languages Visual Basic, C, and Jscript.
• .NET also allows other third-party developers to
  release languages (Eiffel, Perl, Python, Cobol)
  by copy the compiler to your computer and add a
  line to the configuration file in machine.config
• Almost any line in VB.NET and C can be convert
  into an equivalent line in the other.
• Chapter 2 provides a brief overview of language
  overview of both VB.NET and C

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Basic Difference Between C and VB.NET

• VB .NET
• - Not case-sensitive
• Commenting
• a VB comment
• Line termination
• Value a b _
• c
• Conciseness
• If condition true Then
• ..
• End if

• C
• - Case-sensetive
• Commenting
• // c commenting
• / A multi-line
• comment. /
• Line termination
• Value a b
• c
• Conciseness
• If (condition true)
• ..

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Types, Objects, and Namespaces (Chapter 3)

• The basics about classes
• Advanced Class Programming
• Namespaces and Assemblies

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The Basics About Class

• Classes are the definitions of objects class can
  be used to create many instances of the class
  called objects.
• Class Components
• Properties store info about an object
• Methods action within an object, methods are
  used for compound actions that perform a distinct
  task or may change the objects state
• Events provide notification from the control
  that something has happened
• Classes also contain their own code and internal
  set of private data.

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Shared Members

• There are two ways to use .NET classes
• Creating an object first
• Dim SaleProduct As Product
• SaleProdcut New Product()
• Use class member without creating an object
  ?Shared Members which can be accessed by class
  name eg. DateTime.Now without creating a DateTime
  instance first.
• Dim MyDate As DateTime DateTime.Now
• Some class can be used both shared member and
  instance member (DateTime class)

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A simple class and Property

• Public Class Product
• Private _Name As String
• Private _Price As Decimal
• Private _ImageUrl as String
• Public Property Price() As Decimal
• Get
• Return _Price
• End Get
• Set (Value As Decimal)
• _Price Value
• End Set
• End Property
• Public Property ImageUrl() As String
• ..
• End Property
• Public Property Name() As String

Define private variables (class Variables)

• We can make the member variable as public but it
  would allow the client code freely access to
  change any variables. Instead we create property
  procedures to manipulate the code
• Property procedures have two parts
• Procedure to retrieve data
• Procedure to set data

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A Basic Method

• Public Class Product
• Private _Name As String
• Private _Price As Decimal
• Private _ImageUrl as String
• Public Function GetHtml() As String
• Dim HtmlString As String
• htmlString "lth1gt" _Name "lt/h1gtltbrgt"
• htmlString "lth3gtCosts "
  _Price.ToString() Baht lt/h3gtltbrgt"
• HtmlString "ltimg src" _ImageUrl
  "gt"
• Return HtmlString
• End Function
• Public Property Price() As Decimal
• ..
• End Property
• Public Property ImageUrl() As String
• ..

You can add a method to a class by adding a
public function or subroutine to a class. The
product class has GetHtml method that returns a
string representing a formatted block of HTML.
This HTML can be placed on a web page to
represent the product.
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Create and configure the class

• lt
• Dim SaleProduct As New Product()
• SaleProduct.Name PadThai Dish"
• SaleProduct.Price 50
• SaleProduct.ImageUrl "http//localhost/WebSample
  s/home/padthai.jpg"
• Response.write(SaleProduct.GetHtml()) gt

Create Object
Call propertyName, Price And ImpageUrl
Call method GetHtml
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Result
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Constructors

• Product class could have an error if getHTML is
  used but the data has not been supplied.
• Constructor is a special method run when the
  class is first created
• In C, a constructor is the name of the class
• In VB.NET, the constructor always has the name
  New.
• .NET supplies a default constructor that does
  nothing.

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Product Class with Constructor

• Public Class Product
• Public Sub New (name As String, price As Decimal)
• _Name name
• _Price price
• End Sub
• End Class
• To create a Product Object, you need to supply
  info for these parameters, ensuring it will start
  its life with valid information.
• Dim SaleProduct As New Product (Kitchen
  Garbage, 49.99)

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Advanced Class Programming

• Inheritance allow one class to acquire and
  extend the functionality of another class
• You could create a class called TaxableProduct
  that inherits from Product class. TaxableProduct
  class automatically has all the same methods and
  properties as in Product class
• Shared Members shared properties and methods
  without a live object
• MyVal Math.Sin(AngleInRadians)
• To create a shared properties or method, Shared
  (or static in c) keyword is use
• Public Shared ReadOnly Property TaxRate() As
  Decimal
• End Property
• Casting converting class into different data
  tytes

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Namespaces and Assemblies

• Namespaces Every piece of code in .NET exists
  inside a class. And every class exists inside a
  namespace.
• Assemblies all .NET classes are contained in
  assemblies which is the .NET equivalent of
  traditional .exe and .dll files. Two ways to use
  assemblies
• Placing it in the same directory or in a
  subdirectory of the application
• Placing it in the Global Assembly Cache (GAC), a
  system wide store of shared assemblies. All .NET
  classes are a part of the GAC
• Chapter 21 for more detail

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Namespace

• The base class libraries are organized into
  logical groupings of code called namespaces
• Namespaces simplify programming by allowing the
  developer to call methods in the namespace as if
  they were methods in the application.
• The System object is at the top of the namespace
  hierarchy, and all objects inherit from it
• ASP.NET System.Web namespace
• WebForms System.Web.UI namespace
• HTML Server Controls System.Web.UI.Control.HTMLCo
  ntrol
• ASP.NET Server Controls System.Web.UI.Control.Web
  Control
• MSDN reference contains class library reference
  which documents the properties, methods, and
  events of every class in every name space.

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Visual Basic Programming
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Steps for Writing VB Projects

• Design/Define the User Interface
• Plan/Set the Properties
• Plan/Write the Code
• Test and Debug

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Visual Basic Application Files
VB application can consist of one or more
projects. Each project can contain one or more
form.
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Visual Studio Environment

• Where you create and test the project.
• Integrated development environment (IDE)
• Form designer ? create form
• Editor ? entering and modifying codes
• Compiler ?translating VB codes to IL
• Debugger ? locate and correct program errors
• Object browser ? view available classes, objects,
  properties, methods, and events
• Help ? help facility

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IDE Main Window

• Toolbars
• Document Window ?Form designer, code editor,
  object browser and requested help page.
• Form Designer ? form for UI
• Solution Explorer Window ? holds filenames, list
  of classes it references
• Properties Window ? to set properties of the
  objects
• Toolbox ? holds tool used to place controls on a
  form

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IDE Main Window
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VB Toolbox

• Holds the tools you place on a form

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Set Properties - Properties window
Properties window
Namespace and class of selected Object Object ?
Label1 Class? System.Windows.Forms.Label Actual
Class ? Label Namespace ?System.Windows.Forms
Object box
Settings box
Name of selected object
N
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Write Code

• VB Events
• VB will respond to the event and automatically
  execute the procedures.
• VB ignores events for which no procedures are
  written
• VB Event Procedures
• Code in VB is written in procedures.
• Eg. Private Sub
• End Sub
• Automatically named
• Object name and underscore (_) and the name of
  the event
• Eg pushButton_Click procedure

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Editor Window

• Declarations Section
• Class list
• Method list

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Code Statements

• Remark statement
• Comments used for project documentation only (not
  executable).
• Begin with
• Good programming practices must include remarks
  to clarify the projects.

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Code Statements

• Assignment Statement
• Assigns a value to a property or variables
• Operates from right to left
• Object.Property value
• Eg. titleLabel.Text Welcome to Class
• numberInteger 3
• messageLabel.AutoSize True

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Code Statements

• Ending program by executing a method
• Object.Method()
• Method always has parenthesis properties dont
• Eg. helloButton.Hide()
• messageLabel.Show()
• To execute a method of the current object (the
  form itself) use Me keyword
• Me.Close()

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Finding and Fixing Errors

• Syntax errors
• Run-time errors (or Exception)
• Logic Errors

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Finding and Fixing Errors

• Syntax errors
• Punctuation, format or spelling mistakes
• Can be identified as you move off the offending
  line with a blue squiggly line appeared under the
  part of the line.

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Finding and Fixing Errors

• Run-time errors (or Exception)
• Project halts during execution
• Statements that cannot execute correctly cause
  run-time errors.
• Impossible arithmetic operations (dividing by
  zero)
• Logic Errors
• Project runs but produces incorrect results

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Visual Studio Help

• Includes all of the Microsoft Developer Network
  library (MSDN)
• Several books
• Technical articles
• Microsoft knowledge base FAQ questions
• MSDN includes reference materials for the VS IDE,
  the .NET frameword, VB, C, J and C.
• Viewing the help topics
• Contents, Index, or Search
• Context-sensitive help
• Quick way to view Help
• Select a VB object or place the insertion point
  in the word in the editor and press F1