1. Chapter 1: An Introduction To ASP.NET Web Programming
Liu, Jie
Professor
Department of Computer Science
Western Oregon University

2. 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

3. Web Applications
Port
Domain name
Page/file
Parameter #1
Protocol
Path
Start of parameters
Parameter #2

4. 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

5. 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)

6. 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)

7. 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

8. The .Net Framework Structure
Remote users
over Internet
Any Browser
Remote Systems
Over Internet
Any Hardware/OS
Local users
Traditional Window
application
This picture is to show the architecture of the technology at a conceptual level.
Some language compilers are included in the .Net framework. Others such as Cobol would have to be purchased. Java and or J## (Microsoft’s Java Language) would have to be installed separately.
.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

9. 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);

10. 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