Chapter 1: An Introduction To ASP.NET Web Programming

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Chapter 1 An Introduction To ASP.NET Web
Programming

• Liu, Jie

Professor Department of Computer Science
Western Oregon University Liuj_at_wou.edu
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Web Applications

• The Client/Server model -- a computation model
  for PCs to connect to other computers, like the
  monitor and mainframe architecture model.
• Client sends a request
• Thin client
• Thick client
• Server answers the requests
• For Web based applications
• Communication are through HTTP (hypertext
  Transfer Protocol)
• What is a protocol
• Client is a browser such as IE (Internet
  Explorer)
• A browser displays pages defined using HTML tags
  (Hypertext, Markup Language)
• Static pages not going to change
• Dynamic pages formed dynamically according to
  the requests
• The application itself is defined on a web server
  such as IIS (Internet Information Services), with
  in turn may interact with other server such as a
  Database Management System (DBMS) that is hosted
  on a database server

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Web Applications
http//sundown.wou.edu81/en/mail.html?langenlau
reloncal1
Port
Domain name
Page/file
Parameter 1
Protocol
Path
Start of parameters
Parameter 2
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Dynamic Pages

• A dynamic page is generated each time it is
  called
• The same page may be posted back to the server
  for processing.
• Nevertheless, the page itself is stateless, i.e.,
  it will not maintain the value of a variable
  between each loading of the page

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More About State

• State refers to the values of a variable or
  object
• Variables in a web page is stateless meaning that
  they do not remember their previous values
• Methods used to maintain a variables state
  include
• Use view state
• Use session or application state object
• Using static variable (C feature)
• Use cookie
• Use database
• (show Website 3 example and Visual Studio)

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A Closer Look at the example

• The .ASPX page
• Page directives
• lt_at_ Page Language"C" AutoEventWireup"true"
  CodeFile"Default.aspx.cs" Inherits"_Default" gt
• AutoEventWireup allows Page_Load linked with page
  load event and called when the page is loaded
• The .ASPX.CS page
• using System.Web.UI.HtmlControls
• public partial class _Default
  System.Web.UI.Page
• protected void Page_Load(object sender,
  EventArgs e)
• if (IsPostBack)

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A Closer Look at the example

• More about the Visual Studio in coming chapters
• A page and a page behind it (separation of
  presentation and business logic)
• Controls, properties, and events
• If I change nTemp to be a static variable, what
  will happen?
• Different between design view and source view

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The .Net Framework Structure
Remote users over Internet Any Browser
Remote Systems Over Internet Any Hardware/OS
Local users Traditional Window application
.Net Framework
ASP.NET Application Services
Windows Forms Controls Windows Application
Services
Web Forms
Web Services
.Net Compliant Programming Languages VB.NET,
C, C, J, etc
.Net Framework Class Library Common Language
Runtime
Operating System Windows 2000/2003/NT/98/ME/XP
and may be other OSs
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VB, C, and J

• // Declare and initialize a string.string 
• strFruit  "oranges,apples,peaches,kumquats,nectar
  ines,mangos"
• // Declare an array.
• string arrFruit
• // Place each word in an array element.
• arrFruit  strFruit.Split(new Char ',', '.',
  '')
• // Sort the array.
• System.Array.Sort(arrFruit)
• // Put the sorted array back in the string.
• strFruit  System.String.Join(" ", arrFruit)

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Summary

• Have general understanding about the following
• Web applications
• Web page
• Stateless
• ASP.NET components (IIS, frame work, CLR, etc)
• Client/Server
• Dynamic pages
• URL
• Helpful web sites
• www.msdn.microsoft.com
• www.Asp.net