Introducing ASP.NET


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Introducing ASP.NET

by Anand Narayanaswamy

ASP.NET (Active Server Pages) is a new and extended technology to the earlier classic ASP, introduced by Microsoft Corporation, which fully supports Microsoft's .NET Framework. It supplies all the required user interfaces under the name "WebForms" and also works with all .NET languages like Visual C# .NET, Visual Basic .NET etc. WebForms are used to create user interfaces for the web pages. Till now, you've to apply specific HTML tags like <Input> and <Select> for creating user interfaces and ASP scripting using VBScript or JavaScript. But with the introduction of ASP .NET, you need  not apply them any more. All you have to do is to call the custom GUI classes defined in the System.Web.UI.WebControls namespace of the .NET Framework. Moreover, System.Web namespace provides necessary classes, methods and properties for developing client - server applications and System.Web.UI namespace interacts with other .NET language like C#, VB .NET. Therefore, a C# file containing some methods or C# syntaxes can be easily called in your ASP applications.     These topics will be examined in greater detail in the coming sections. 

Benefits of ASP.NET

One major advantage of ASP.NET is that, you can apply the programming techniques of other .NET languages like C#, 
VB.NET etc. Hence, if you are conversant with any one language of .NET Framework, then it'll be easy for you to write 
ASP.NET programs. Moreover, it eliminates the need for learning complex syntaxes. Another benefit of ASP.NET is that it supplies built-in controls for validations. Earlier you've to apply complex Java Scripts or VBScripts for validating form elements. Hence, all the essential tools for developing and deploying ASP applications is now under a single umbrella of Microsoft .NET. 

Basic requirements for ASP.NET

  1. Microsoft Windows NT Server 4.0, Microsoft Windows 2000, Microsoft Windows XP. 
  2. .NET Framework SDK.
  3. Text Editor like Notepad. 
  4. Internet Explorer 5.5 and above.
  5. Visual Studio .NET (Optional, but recommended).

Note: You have to install Microsoft Data Access Components 2.7 before installing .NET Framework SDK. You can download the same by clicking here. Please go through the additional notes given at the end of this article regarding Visual Studio .NET. 

There are two phases involved in the ASP.NET development cycle, which are
a) User Interface phase
b) Coding phase. 
It's the User Interface phase which we'll call 'WebForms'. So, before moving on to the coding phase, it's essential for you to be aware of all types of user interfaces that .NET Framework providesIf you're familiar with 'WinForms', then you are more likely to confuse it with WebForms. Keep in mind that WinForms are used to develop standalone GUI applications (Which can be executed by triggering the relevant .exe file), whereas WebForms are used to create Web based applications like Java Applets and for creating user interfaces for ASP applications. 

Your First WebForm Program

Copy or enter the following code in Notepad and save the file as Firstwebform.aspx under Inetpub/wwwroot directory:

<form method = "post" runat = "server">
<asp:TextBox runat = "server" ></asp:TextBox>
If you save the above file in a directory under the www root, then you've to configure for the directory alias using personal web manager. Please review the additional notes given at the end of this article regarding configuration of Personal Web Manager. The execution of this file is very similar to that of classic ASP. Only thing you've to remember is to supply the correct extension for ASP.NET, which is .aspx. 

A WebForm control is created using the following syntax: 

<form method = "post" runat = "server">
<asp:ControlName runat = "server"></asp:ControlName>

The runat attribute is compulsory without which your code will not compile correctly. From the above code, it can be seen that ASP.NET follows the syntax of XML. 

Working with controls

ASP.NET provides lot of controls for building powerful user interfaces. Important among them are Buttons, Radio Buttons, Check Boxes, List Box, Combo Box. The .NET Framework also supplies advanced controls like Calendar, AdRotator etc. In the following sections, Ill cover each of these controls with the help of simple examples.  

Buttons are used to trigger actions. Without buttons, we cannot do any sort of work on the form.

<form method = "post" runat = "server">
<asp:Button id = "b1" runat = "server" text = "OK" ToolTip = "Click here">

Radio Buttons
With radio buttons, you can select only one item at a time. Only thing you've to remember is that t
he GroupName attribute should be same for radiobuttons. 

<form method = "post" runat = "server">
Select your choice: <asp:RadioButton id = "r1" runat = "server" Text = "Male" 
GroupName = "g1"></asp:RadioButton>

<asp:RadioButton id = "r2" runat = "server" Text = "Female" 
GroupName = "g1"></asp:RadioButton>

Checkboxes enables you to select any number of items at a time. It can be activated either by clicking on it or by hitting the space bar.  

<form method = "post" runat = "server">
Choose: <asp:CheckBox id = "c1" runat = "server" Text = "Television"></asp:CheckBox>
<asp:CheckBox id = "c2" runat = "server" Text = "PC" ></asp:CheckBox>
<asp:CheckBox id = "c3" runat = "server" Text = "Telephone" ></asp:CheckBox>

This control looks like a typical combo box in Visual Basic. Users can select any one item at a time. 

<form method = "post" runat = "server">
<asp:DropDownList runat = "server">
       <asp:ListItem id = "d1" runat = "server" value = "India">India</asp:ListItem>
       <asp:ListItem id = "d2" runat = "server" value = "China" >China</asp:ListItem>
       <asp:ListItem id = "d3" runat = "server" value = "Russia">Russia</asp:ListItem>
       <asp:ListItem id = "d4" runat = "server" value = "USA">USA</asp:ListItem>
       <asp:ListItem id = "d5" runat = "server" value = "UK">UK</asp:ListItem>

List Box
With List box, you can select multiple number of items by scrolling up and down.  

<form method = "post" runat = "server">
<asp:ListBox runat = "server">
        <asp:ListItem id = "l1" runat = "server" value = "India">India</asp:ListItem>
        <asp:ListItem id = "l2" runat = "server" value = "China" >China</asp:ListItem>
        <asp:ListItem id = "l3" runat = "server" value = "Russia">Russia</asp:ListItem>
        <asp:ListItem id = "l4" runat = "server" value = "USA">USA</asp:ListItem>
        <asp:ListItem id = "l5" runat = "server" value = "UK">UK</asp:ListItem>

Image Button
You can create a button with an image on it. Try out the following code and observe the output:

<form method = "post" runat = "server">
<asp:ImageButton id = "b10" runat = "server" src = "f:\logo.gif"></asp:ImageButton>

This is an advanced control in ASP.NET. Your users can choose a date with the help of this control. Try out by copying the following piece of code:  

<form method = post runat = "server">
<asp:Calendar id ="c1" runat = 'server"></asp:Calendar>

About Visual Studio .NET

Visual Studio .NET, shortly VS.NET, provides a very easy way for designing user interfaces using WebForms. You are required to just place the controls from the Toolbox to the form and set relevant properties form the properties dialog box, just like Visual Interdev 6.0. Now Visual Studio .NET provides a single development environment with which you can develop any .NET applications using any .NET language. In the earlier version, viz., Visual Studio 6.0, each language had a separate environment. Hence, developers faced many problems while migrating from one language to another. They have to understand the new environment and learn new syntax while migrating from Visual Basic 6.0 to Visual C++ 6.0. These difficulties are eliminated with the introduction of .NET technology and Visual Studio .NET. 


Configuring Personal Web Manager

Start the manager by selecting Start | Programs | Administrative Tools | Personal Web Manager. If the server has not been started, then click on the start button to start the same. Click on the Advanced button and click Add button. Type an alias name and browse for your current folder. Make sure that the execute button is checked and the directory you created is under the Inetpub/wwwroot directory.  

Execution URL without creating an alias                 : http://localhost/Yourfilename.aspx 
Execution URL by creating an alias named 'internet': http://localhost/internet/Yourfilename.aspx 
Localhost can also be substituted with the local IP address  

If Personal Web Manager is not found under the above mentioned menu, then you've to install the same from the control panel. Just follow the steps given below. 

Click on Start | Settings | Control Panel | Add/Remove Programs | Add/Remove Windows Components and choose Internet Information Services (IIS). Click on the details button and checkmark Personal Web Manager. 

As a last step, click the Next button. Windows will install the required components. Make sure to insert the Windows 2000 installation CD, when prompted.


Try - Yourself Questions

State whether the following statements are true or false

1) ASP stands for Active Service Pages
2) ASP.NET works under Windows 98 OS. 
3) It's not neccessary to install Microsoft Data Access Components 2.7, in order to develop ASP.NET applications. 
4) ASP.NET applications can be developed using Visual Studio 6.0.
5) It's neccessary to learn XML before learning ASP .NET.
6) Groupname should have to be different for creating radio buttons. 
7) The runat attribute is compulsory in the syntax of a WebForm control. 
8) WebForm and WinForm are not same. If true, point out valid reasons. 
9) "Combobox" control is a valid WebForm control. 
10) Check out the code given below and point out any mistakes: 
      <asp - textbox runat = server><asp-textbox>


About the Author

Anand Narayanaswamy works as a freelance Web developer, freelance writer, and as an instructor in Thiruvananthapuram, Kerala State, India. He runs learnxpress.com and provides free technical support to users worldwide through the site besides featuring tutorials and articles related to Java, C#, Visual Basic, and other web technologies like ASP, XML etc. You can browse his online personal site at http://www.learnxpress.com/anandn

This article was originally published on October 1st, 2002

About the Author

Anand Narayanaswamy

Anand Narayanaswamy (Microsoft MVP) is a freelance writer for Developer.com and Codeguru.com. He works as an independent consultant and runs NetAns Technologies (http://www.netans.com)which provides affordable web hosting services. He is the author of Community Server Quickly (http://www.packtpub.com/community-server/book). Anand also runs LearnXpress.com (http://www.learnXpress.com) and Dotnetalbum.com (http://www.dotnetalbum.com) and regularly contributes product and book reviews for various websites. He can be reached at ananddotnet@yahoo.co.in

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