Chapter 1: An Introduction To ASP.NET Web Programming

Liu, JieProfessor

Department of Computer Science Western Oregon University

Liuj@wou.edu

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

Web Applications

Domain name

Path

http://sundown.wou.edu:81/en/mail.html?lang=en&laurel=on&cal=1

Protocol

PortPage/file

Start of parameters

Parameter #1

Parameter #2

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

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 variable’s 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)

A Closer Look at the example The .ASPX page

• Page directives <%@ Page Language="C#" AutoEventWireup="true"

CodeFile="Default.aspx.cs" Inherits="_Default" %>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) … …

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

The .Net Framework StructureRemote users over InternetAny Browser

Remote SystemsOver Internet

Any Hardware/OS

Local usersTraditional Window

application

ASP.NET

Application Services

Web Forms Web Services

Windows FormsControls Windows Application

Services

.Net Compliant Programming Languages **VB.NET, C++, C#, J++, etc

.Net Framework Class Library

Common Language Runtime

Operating SystemWindows 2000/2003/NT/98/ME/XP and may be other OSs

.Net Framework

VB, C#, and J++// Declare and initialize a string.string 

strFruit = "oranges,apples,peaches,kumquats,nectarines,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);

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