Web service in custom AJAX control

 Hello

I want to create a custom Ajax control which get data from web service. Control has two properties: userId and appId. I call service in initialize function in prototype.

 
AjaxDynamicArticle.ClientDynamicArticle = function(element) {
AjaxDynamicArticle.ClientDynamicArticle.initializeBase(this, [element]);
this._appId=null;
this._userId=null;
this._html=null;
}

AjaxDynamicArticle.ClientDynamicArticle.prototype = {
initialize: function() {
AjaxDynamicArticle.ClientDynamicArticle.callBaseMethod(this, 'initialize');
tempuri.org.ServiceForAjax.GetArticle(this._user ...