How to Pass Information from Server-Side Code to Client-Side Code in AJAX Control Extender?

Hi All,
For some reason I can't get the following to work: I have a custom AJAX Control Extender with a few getters and setters. I also have some images I want to use with the extender saved in a resource file. How to I make the respective image URLs available to the javascript of the extender? Are there any examples available?
Thanks!
[Update: renamed the subject to something more appropriate.] 

Perhaps I can clarify a bit:
I have set up a getter and setter to set the image URL from the resource file:
 
1    [ExtenderControlProperty]
2    public string CoverURL
3    {
4    	get { return GetPropertyValue("CoverURL", ""); }
5    	set { SetPropertyValue("CoverURL", value); }
6    }
7    
8    protected override void  OnInit(EventArgs e)
9    {
10   	this.CoverURL = Page.ClientScript.GetWebResourceUrl(this.GetType(), "AjaxControlExtender1.Resources.spacer.png");
11   	base.OnInit(e);
12   }
 And the following in the JS file:
 
1    get_CoverURL : function () { return this._CoverURL; },
2    set_CoverURL : function (value) { this._CoverURL = value; },
Is there a way to populate this._CoverURL on the client-side without using extender properties? I don't want to expose this as a property to the developer using my Control Extender. 
Thanks! 

 Hi,
Thank you for your post!
I think you can do this in GetScriptDescriptors method:

        protected override IEnumerable GetScriptDescriptors(Control targetControl)
        {
            ScriptBehaviorDescriptor descriptor = new ScriptBehaviorDescriptor("Samples.FocusBehavior", targetControl.ClientID);
            descriptor.AddProperty("CoverURL ", Page.ClientScript.GetWebResourceUrl(this.GetType(), "AjaxControlExtender1.Resources.spacer.png"));

            return new ScriptDescriptor[] { descriptor };
        }
For more information, see http://msdn2.microsoft.com/zh-cn/library/bb386403.aspx.
If you have further questionss,let meknow!
Best Regards, 


 
Sincerely,
Jin-Yu Yin
Microsoft Online Community Support