Microsoft Developer Network (MSDN)

ASP.NET AJAX

ASP.NET AJAX provides a framework for building rich, interactive user interfaces for your ASP.NET Web Forms applications. It enables you to create dynamic pages that update portions of the page without requiring a full postback to the server, leading to a more responsive and desktop-like user experience.

Key Features and Concepts

• Client-Side Scripting: Leverages JavaScript and a rich set of client-side controls and components.
• Partial Page Updates: Allows specific parts of a Web page to be updated asynchronously, improving performance and usability.
• ScriptManager and UpdatePanel: Core components for enabling AJAX functionality in Web Forms.
• Extender Controls: Enhance the functionality of existing ASP.NET controls with AJAX-enabled features.
• Web Services Integration: Seamlessly call server-side web methods from client-side scripts.

Getting Started with ASP.NET AJAX

To enable ASP.NET AJAX in your Web Forms application, you typically need to add a ScriptManager control to your page:

<asp:ScriptManager ID="ScriptManager1" runat="server" />

Then, you can wrap the content you want to update asynchronously within an UpdatePanel:

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
    <ContentTemplate>
        <!-- Content to be updated -->
        <asp:Label ID="lblMessage" runat="server" Text="Initial content." />
        <asp:Button ID="btnUpdate" runat="server" Text="Update Content" OnClick="btnUpdate_Click" />
    </ContentTemplate>
</asp:UpdatePanel>

In your server-side code-behind (e.g., Default.aspx.cs):

protected void btnUpdate_Click(object sender, EventArgs e)
{
    lblMessage.Text = "Content updated at: " + DateTime.Now.ToString();
}

Advanced Topics

• Triggers: Define which controls will initiate an asynchronous postback within an UpdatePanel.
• Asynchronous Data Retrieval: Efficiently fetch data from the server without blocking the UI.
• Client-Side Framework: Understand the JavaScript library provided by ASP.NET AJAX for manipulating the DOM and handling events.
• Custom Extenders: Develop your own reusable AJAX components.

Resources

• Official ASP.NET AJAX Documentation (Link would point to a specific MSDN page)
• ASP.NET AJAX Samples and Tutorials
• Introduction to ASP.NET AJAX