ASP.NET 3.5 and Visual Studio 2008 ...

Prior to Visual Studio 2008, the ASP.NET AJAX product used to be a separate installation that you were required to install on your machine and the Web server that you were working with. This release gained in popularity quite rapidly and is now a part of the Visual Studio 2008 offering. Not only is it a part of the Visual Studio 2008 IDE, the ASP.NET AJAX product is also baked into the .NET Framework 3.5. This means that to use ASP.NET AJAX, you don need to install anything if you are working with ASP.NET 3.5.

ASP.NET AJAX is now just part of the ASP.NET framework. When you create a new Web application, you do not have to create a separate type of ASP.NET application. Instead, all ASP.NET applications that you create are now AJAX-enabled.

If you have already worked with ASP.NET AJAX prior to this 3.5 release, you will find that there is really nothing new to learn. The entire technology is seamlessly integrated into the overall development experience.

Overall, Microsoft has fully integrated the entire ASP.NET AJAX experience so you can easily use Visual Studio and its visual designers to work with your AJAX-enabled pages and even have the full debugging story that you would want to have with your applications. Using Visual Studio 2008, you are now able to debug the JavaScript that you are using in the pages.

In addition, it is important to note that Microsoft focused a lot of attention on cross-platform compatibility with ASP.NET AJAX. You will find that the AJAX-enabled applications that you build upon the .NET Framework 3.5 can work within all the major up-level browsers out there (e.g., Firefox and Opera).
Developing with ASP.NET AJAX

There are a couple of types of Web developers out there. There are the Web developers who are used to working with ASP.NET and who have experience working with server-side controls and manipulating these controls on the server-side. Then there are developers who concentrate on the client-side and work with DHTML and JavaScript to manipulate and control the page and its behaviors.

With that said, it is important to realize that ASP.NET AJAX was designed for both types of developers. If you want to work more on the server-side of ASP.NET AJAX, you can use the new ScriptManager control and the new UpdatePanel control to AJAX-enable your current ASP.NET applications with little work on your part. All this work can be done using the same programming models that you are quite familiar with in ASP.NET.

In turn, you can also use the Client Script Library directly and gain greater control over what is happening on the client is machine. Next, this article looks at building a simple Web application that makes use of AJAX.
ASP.NET AJAX Applications

The next step is to build a basic sample utilizing this new framework. First create a new ASP.NET Web Site application using the New Web Site dialog. Name the project AJAXWebSite. You will notice (as shown here in Figure 1) that there is not a separate type of ASP.NET project for building an ASP.NET AJAX application because every ASP.NET application that you now build is AJAX-enabled.




After you create the application, you will be presented with what is now a standard Web Site project. However, you may notice some additional settings in the web.config file that are new to the ASP.NET 3.5. At the top of the web.config file, there are new configuration sections that are registered that deal with AJAX. This section of web.config is presented in Listing 1.

Listing 1: The <configSections> element for an ASP.NET 3.5 application

<?xml version="1.0"?>


<configuration>
  <configSections>
     <sectionGroup name="system.web.extensions"
      type="System.Web.Configuration.SystemWebExtensionsSectionGroup,
        System.Web.Extensions, Version=3.5.0.0, Culture=neutral,
        PublicKeyToken=31BF3856AD364E35">
        <sectionGroup name="scripting"
         type="System.Web.Configuration.ScriptingSectionGroup,
            System.Web.Extensions, Version=3.5.0.0, Culture=neutral,
            PublicKeyToken=31BF3856AD364E35">
          <section name="scriptResourceHandler"
           type="System.Web.Configuration.ScriptingScriptResourceHandlerSection,
              System.Web.Extensions, Version=3.5.0.0, Culture=neutral,
              PublicKeyToken=31BF3856AD364E35" requirePermission="false"
           allowDefinition="MachineToApplication"/>
            <sectionGroup name="webServices"
             type="System.Web.Configuration.ScriptingWebServicesSectionGroup,
               System.Web.Extensions, Version=3.5.0.0, Culture=neutral,
               PublicKeyToken=31BF3856AD364E35">
               <section name="jsonSerialization"
                type="System.Web.Configuration.ScriptingJsonSerializationSection,
                   System.Web.Extensions, Version=3.5.0.0, Culture=neutral,
                   PublicKeyToken=31BF3856AD364E35" requirePermission="false"
                allowDefinition="Everywhere" />
               <section name="profileService"
                type="System.Web.Configuration.ScriptingProfileServiceSection,
                   System.Web.Extensions, Version=3.5.0.0, Culture=neutral,
                   PublicKeyToken=31BF3856AD364E35" requirePermission="false"
                allowDefinition="MachineToApplication" />
              <section name="authenticationService"
              type="System.Web.Configuration.ScriptingAuthenticationServiceSection,
                 System.Web.Extensions, Version=3.5.0.0, Culture=neutral,
                 PublicKeyToken=31BF3856AD364E35" requirePermission="false"
              allowDefinition="MachineToApplication" />
              <section name="roleService" 
               type="System.Web.Configuration.ScriptingRoleServiceSection,
                  System.Web.Extensions, Version=3.5.0.0, Culture=neutral,
                  PublicKeyToken=31BF3856AD364E35" requirePermission="false"
               allowDefinition="MachineToApplication" />
            </sectionGroup>
         </sectionGroup>
      </sectionGroup> 
   </configSections>


<!-- Configuraiton removed for clarity -->
 
</configuration>

With the web.config file in place (as provided by the ASP.NET Web Site project type), the next step is to build a simple ASP.NET page that does not yet make use of AJAX.
Building a Simple ASP.NET Page Without AJAX

The first step is to build a simple page that does not yet make use of the AJAX capabilities offered by ASP.NET 3.5. Your page needs only a Label control and Button server control. The code for the page is presented in Listing 2.

Listing 2: A simple ASP.NET 3.5 page that does not use AJAX

VB

<%@ Page Language="VB" %>


<script runat="server">
    Protected Sub Button1_Click(ByVal sender As Object, _
       ByVal e As System.EventArgs)


        Label1.Text = DateTime.Now.ToString()
    End Sub</script>


<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>My Normal ASP.NET Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:Label ID="Label1" runat="server"></asp:Label>   
        <br />
        <br />
        <asp:Button ID="Button1" runat="server" Text="Click to get machine time"
            onclick="Button1_Click" />>
    </div>
    </form>
</body>
</html>

C#

<%@ Page Language="C#" %>


<script runat="server">
    protected void Button1_Click(object sender, EventArgs e)
    {
        Label1.Text = DateTime.Now.ToString();
    }
</script>

When you pull this page up in the browser, it contains only a single button. When the button is clicked, the Label control that is on the page is populated with the time from the server machine. Before the button is clicked, the page is code is similar to the code presented in Listing 3.

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