Files to look at:

• Default.aspx (VB: Default.aspx)
• Default.aspx.cs (VB: Default.aspx.vb)

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This example explains how to populate a cascading ASPxComboBox by using WebMethods. On the client side, the master ASPxComboBox is subscribed to the SelectedIndexChanged event. When the event is raised, it sends a request to the server by WebMethod. If the request is successful, a child ASPxComboBox is populated with the response object.

On the client side, WebMethod is called by the following code:

PageMethods.GetData(id, OnSuccess);

On the server side, ScriptManager is used with EnablePageMethods set to "True":

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

The C# method is marked by WebMethodAttribute:

using System.Web.Services;

[WebMethod]
public static List<Product> GetData(string categoryID) {
        //method code
}