Developing an ASP.NET Web Application

Developing an ASP.NET Web Application
Rishi Kothari

Agenda
Overview of .NET
Overview of ASP.NET
Creating an ASP.NET Web Form
Adding Event Procedures
Validating User Input

Overview of .NET

What is the .NET Framework? Developer Tools Clients User Experiences ASP.NET Web Applications XML Web Services Databases .NET Framework

Benefits of .NET
Based on Web standards and practices
Functionality of .NET classes is universally available
Code is organized into hierarchical namespaces and classes
Language independent
Solves existing problems:
Even with the Internet, most applications and devices have trouble communicating with each other
Programmers end up writing infrastructure instead of applications
Programmers have had to limit their scope or continually learn new languages

The .NET Framework Components Win32 Common Language Runtime .NET Framework Class Library ADO.NET and XML XML Web Services User Interface Visual Basic C++ C# ASP.NET Perl Python … Message Queuing COM+ (Transactions, Partitions, Object Pooling) IIS WMI

The Common Language Runtime
One runtime for all . NET-Based Languages
Manages threads and memory
Garbage collection
Enforces code security
Eliminates DLL versioning problems
Multiple versions of a DLL can run simultaneously
Applications can specify a version of a DLL to use

Using the Class Library
The class library is a set of classes (properties and methods) that all .NET applications can use
You use objects by referencing the .NET namespaces
Using a namespace in C#:
Implicit object declaration
Explicit object declaration
using namespace_name ; using System.Web.UI.WebControls; ListBox ListBox1; ListBox1.Items.Add("First Item"); System.Web.UI.WebControls.ListBox ListBox1; ListBox1.Items.Add("First Item");

Multiple Language Support
The .NET Framework is designed to support many languages
More than 20 languages currently supported
Microsoft provides Visual Basic .NET, C#, Visual J# .NET, and JScript .NET
Benefits of multiple-language support
Code modules are reusable
Class Library access is the same for all languages
The right language is used for the right task
Performance is roughly equal between all languages

Choosing a Language
.NET Framework class library is the same regardless of language
Performance
All languages are compiled to MSIL
Only performance difference is how each language compiler compiles to MSIL
The runtime compiles all MSIL the same, regardless of its origin
Development experience
C# is similar to Java, C, Visual C++, and Pascal
Visual Basic .NET is similar to Visual Basic
Browser compatibility
ASP.NET code is server-side code, so browser compatibility is not an issue

Overview of ASP.NET

ASP Web Application Architecture Presentation Tier Business Logic Tier Data Tier UI Pages (.htm) Graphic Files COM Objects Data Source ADO COM+ Services ASP Page (.asp)

ASP.NET Web Application Architecture Presentation Tier Business Logic Tier Data Tier Graphic Files UI Pages (.htm) XML Web Services (.asmx) User Controls (.ascx) Code-Behind File (.aspx.vb or .aspx.cs) Proxy ADO.NET .NET Objects Data Source COM+ Services COM Objects RCW Web Form (.aspx)

ASP.NET Coding Changes
Page directives
Language attribute must be in set the @Page directive
Structural changes
All functions and variables must be declared within a <script> block
Only one language per page
Render Functions are no longer supported; use Response.Write
Design-Time controls are no longer supported
Replaced with Web controls

ASP.NET Runtime Compilation and Execution Native code C# Visual Basic .NET default.aspx Common Language Runtime HTML Which language? Visual Basic .NET compiler C# compiler MSIL JIT compiler

Multimedia: ASP.NET Execution Model

Creating an ASP.NET Web Form

Demonstration: Developing an ASP.NET Web Application
Create a Web application
Add controls to a Web Form
View the HTML generated
Add an event procedure

What Is a Web Form?
. aspx extension
Page attributes
@ Page directive
Controls save state
Body attributes
Form attributes
<%@ Page Language="C#" Inherits=Project.WebForm1 %> <html> <body ms_positioning="GridLayout"> <form id="Form1" method="post" runat="server" > </form> </body> </html>

What is a Server Control?
Runat="server"
Event procedures run on the server
View state saved
Properties and methods are available in server-side event procedures
<asp:Button id="Button1" runat="server" Text="Submit"/> private void btn_Click(object sender, System.EventArgs e) { lblName.Text = txtName.Text; }

Types of Server Controls
HTML server controls
Based on HTML elements
Exist within the System.Web.UI.HtmlControls namespace
Web server controls
Exist within the System.Web.UI.WebControls namespace
HTML that is generated by the control
<input name="TextBox1" type="text" value="Text_to_Display" Id="TextBox1"/> <asp:TextBox id="TextBox1" runat="server">Text_to_Display </asp:TextBox> <input type="text" id="txtName" runat="server" />

Maintaining the State of ASP.NET Server Controls
Server control state is stored in __VIEWSTATE, a hidden control on the Web Form
__VIEWSTATE stores state in a string value of name-value pairs
<form id="Form1" method="post" runat="server"> <input type="hidden" name="__VIEWSTATE" value="dDw3NzE0MTExODQ7Oz4=" /> 'HTML here </form>
On by default, adjustable at Web Form and control level
<%@ Page EnableViewState="False" %> <asp:ListBox id="ListName" EnableViewState="true" runat="server"> </asp:ListBox>

Demonstration: Using Server Controls to a Web Form
Using HTML server controls
Displaying browser-specific HTML

Selecting the Appropriate Control You need specific functionality such as a calendar or ad rotator The control will interact with client and server script You are writing a page that might be used by a variety of browsers You are working with existing HTML pages and want to quickly add ASP.NET Web page functionality You prefer a Visual Basic-like programming model You prefer an HTML-like object model Use Web Server Controls if: Use HTML Server Controls if: Bandwidth is not a problem Bandwidth is limited

Adding Event Procedures

How to Implement Code
Three methods for adding code:
Put code in the same file as content (mixed)
Put code in a separate <SCRIPT> section of the content file (inline code)
Put code in a separate file (code-behind pages)
Code-behind pages are the Visual Studio .NET default
Form1.aspx Form1.aspx Form1.aspx.vb or Form1.aspx.cs <tags> <tags> code code Separate files Single file Code-Behind Page

Understanding How Code-Behind Pages Work
Create separate files for user interface and interface logic
Use @ Page directive to link the two files
Page1.aspx <% @ Page Language="C#" Inherits="Project.WebForm1" Codebehind="Page1.aspx.cs" Src = "Page1.aspx.cs" %> Page1.aspx.cs namespace Project { public class WebForm1 : System.Web.UI.Page { } }

What are Event Procedures?
Action in response to a user’s interaction with the controls on the page

Demonstration: Using Events
Open an ASP.NET page with controls and client-side and server-side event procedures
Click on the controls to view client-side and server-side events running
In the browser, view the source of the page
In the editor, view the event procedure code

Client-Side Event Procedures Internet .HTM Pages
Typically used only with HTML controls
Interpreted by the browser and run on the client
Do not have access to server resources
Use <SCRIPT language=" language ">

Server-Side Event Procedures
Used with both Web and HTML server controls
Code is compiled and run on the server
Have access to server resources
Use <SCRIPT language ="language" runat="server">
Internet .ASPX Pages

Creating Event Procedures
Visual Studio .NET declares variables and creates an event procedure template in the code-behind page
protected System.Web.UI.WebControls.Button btn ; private void InitializeComponent() { this. btn.Click += new System.EventHandler(this. btn_Click ); } private void btn_Click (object sender, System.EventArgs e) { }

Events in the Web page generation process
ASP.NET server control events are handled when the Web page is posted back to the server
Use the Page.IsPostback property to determine if the Web page is being generated for the first time
Events in the Web Page Generation Process private void Page_Load(object sender, System.EventArgs e) { if (!Page.IsPostBack) { // executes only on initial page load } //this code executes on every request } Page_Unload Page_Init Page_Load Server control events

Multimedia

Demonstration: Handling Postback Events

Validating User Input

What Is Input Validation?
Verifies that a control value is correctly entered by the user
Blocks the processing of a page until all controls are valid
Avoids spoofing or the addition of malicious code

Client-Side and Server-Side Validation
ASP.NET can create both client-side and server-side validation
Client-side validation
Dependent on browser version
Instant feedback
Reduces postback cycles
Server-side validation
Repeats all client-side validation
Can validate against stored data
Valid? Valid? User Enters Data No No Yes Yes Error Message Client Server Web Form Processed

ASP.NET Validation Controls Compare to a custom formula CustomValidator Summarize the state of the validation controls on a page ValidationSummary Compare to a regular expression pattern RegularExpressionValidator Compare to a range RangeValidator Compare to another control, a value, or a data type CompareValidator Require user input RequiredFieldValidator Purpose Control Name

Adding Validation Controls to a Web Form
Add a validation control
Select the input control to validate
Set validation properties
1 2 3 <asp:TextBox id="txtName" runat="server" /> <asp: Type_of_Validator id=" Validator_id " runat="server" ControlToValidate=" txtName " ErrorMessage=" Message_for_error_summary " Display=" static|dynamic|none " Text=" Text_to_display_by_input_control "> </asp: Type_of_Validator>

Combining Validation Controls
Can have multiple validation controls on a single input control
Only the RequiredFieldValidator checks empty controls

Demonstration: Using Validation Controls
Create an ASP.NET Web Form with TextBox and Button controls
Add a RequiredFieldValidator control
Add a RangeValidator control
Add a RegularExpressionValidator control
Add a ValidationSummary control

Thanks!

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Developing an ASP.NET Web Application

by Rishi Kothari on Jan 07, 2007

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Developing an ASP.NET Web Application — Presentation Transcript