how to notify ajax call multiple times during web method process?

how to notify ajax call multiple times during web method process? 

    [System.Web.Script.Services.ScriptMethod(ResponseFormat = System.Web.Script.Services.ResponseFormat.Json)]
    [System.Web.Services.WebMethod(BufferResponse = true, CacheDuration = 0, EnableSession = false)]
    public static void UploadFiles1()
    {
        myClass.Upload();
        myClass.NotifyProcess += myClass_OnNotifyProcess;
    }
    private void myClass_OnNotifyProcess(string sMsg)
    {

        var h = System.Web.HttpContext.Current; ;
        System.Collections.Generic.Dictionary<string, string> d = new System.Collections.Generic.Dictionary<string, string>();
        d.Add("aa", "xxxx--" + DateTime.Now.ToString() + "  </br>");
        string s = (new System.Web.Script.Serialization.JavaScriptSerializer()).Serialize(d);


        h.Response.Write(s);

    }

$.ajax({
                    type: "POST",
                    url: window.location.href + "/UploadFiles",
                    contentType: "application/json; charset=utf-8",
                    dataType: "json",
                    //dataType: "text/plain",
                    cache: false,
                    success: function (response) {
                        alert("succ--  " + response.d);
                        console.log(response);
                        console.log(response.d);
                    },
                    error: function (response) {
                        alert(response.responseText);
                        console.log(response.d);
                    }
                })
                ;

well.. the event still haven't implemented.. so i use this method instead...

 [System.Web.Script.Services.ScriptMethod(ResponseFormat = System.Web.Script.Services.ResponseFormat.Json)]
    [System.Web.Services.WebMethod(BufferResponse = true, CacheDuration = 0, EnableSession = false)]
    public static void UploadFiles()
    {
        var h = System.Web.HttpContext.Current; ;
        if (!(h.User != null && h.User.Identity.IsAuthenticated))
            return;// "";

        //h.Response.ContentType = "text/plain";
        //string s = "xxxx--" + DateTime.Now.ToString() + "  </br>";

        System.Collections.Generic.Dictionary<string, string> d = new System.Collections.Generic.Dictionary<string, string>();
        d.Add("aa", "xxxx--" + DateTime.Now.ToString() + "  </br>");
        string s = (new System.Web.Script.Serialization.JavaScriptSerializer()).Serialize(d);


        h.Response.Write(s);


        System.Threading.Thread.Sleep(1500);
        h.Response.Write(s);

        System.Threading.Thread.Sleep(2500);
        h.Response.Write(s);

    }

at the moment i get all the events/Thread.Sleep messages at ones..

but i would like to show the msg each at its time.

so beside using recursive ajax call to the end of process..

some body could suggest an alternative solution?   

thank you