NETにおけるCallBackのコールバック技術

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class Test : System.Web.UI.Page,ICallbackEventHandler
{
    string Resultstr = "";

    protected void Page_Load(object sender, EventArgs e)
    {
             //
    }

    public void RaiseCallbackEvent(string eventArgument)
    {
        Resultstr = "   ：" + eventArgument;
    }

    public string GetCallbackResult()
    {
        return Resultstr;
    }
}