Custom AJAX extender control - klicanje s codebehind

Naredil sem custom ajax extender, ki ga pripnem na gumb (server control). Spodnji primer je trivialen, ampak gumb na katerem definiram ta extender zažene alert('OK') v spodnji JS datoteki, kar deluje po pričakovanjih. Zanima me kako pognati ta isti "alert" preko codebehind. V .cs datoteki imam metodo CallMethod(), ki bi po mojem razumevanju nekako morala poklicati funkcijo v .js.

Hvala za kakršno koli idejo!

extendercontrol.cs

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
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;
using System.Xml.Linq;


namespace AExtender
{
    [
        TargetControlType(typeof(Button))
    ]
    public class ExtenderControl1 : ExtenderControl
    {
        protected override IEnumerable<ScriptDescriptor>
                GetScriptDescriptors(System.Web.UI.Control targetControl)
        {
            ScriptBehaviorDescriptor descriptor = new ScriptBehaviorDescriptor("AExtender.ClientBehavior1", targetControl.ClientID);
            yield return descriptor;
        }

        // Generate the script reference
        protected override IEnumerable<ScriptReference>
                GetScriptReferences()
        {
            yield return new ScriptReference("AExtender.ClientBehavior1.js", this.GetType().Assembly.FullName);
        }

        protected void CallMethod()
        {
            // Del kjer naj bi extender pognal preko codebehind z enakim efekotom kot z gumbom
        }
    }
}

in ClientBehavior1.js

Type.registerNamespace("AExtender");

AExtender.ClientBehavior1 = function(element) {
    AExtender.ClientBehavior1.initializeBase(this, [element]);

    var _clickDelegate = null;
}

AExtender.ClientBehavior1.prototype = {
    initialize: function () {
        AExtender.ClientBehavior1.callBaseMethod(this, 'initialize');
        var e = this.get_element();
        e.onclick = function () { return false };

        this._clickDelegate = Function.createDelegate(this, this._onClickDelegate);
        $addHandler(e, "click", this._clickDelegate);
    },

    _onClickDelegate: function (sender, ea) {
        alert('OK');
    },

    dispose: function () {
        AExtender.ClientBehavior1.callBaseMethod(this, 'dispose');
    }
}
AExtender.ClientBehavior1.registerClass('AExtender.ClientBehavior1', Sys.UI.Behavior);

if (typeof(Sys) !== 'undefined') Sys.Application.notifyScriptLoaded();