Ajax.PradoCallback = Class.create({
  initialize: function(element, eventName, value, options) {
    options = options || { };
    if (options.HasPriority == null)
      options.HasPriority = false;

    this.transport = new Prado.CallbackRequest('ctl0$ContMain$Ajax', options);
    this.transport.setCallbackParameter({
      Value:     value || '',
      EventName: eventName,
      ClientID:  $(element).identify().camelize()
    });
    this.transport.dispatch();
  }
});

Element.addMethods({
  callback: function(element, eventName, value, options) {
    new Ajax.PradoCallback(element, eventName, value, options);
    return $(element);
  },

  updateByCallback: function(element, eventName, value, options) {
    options = Object.clone(options);
    var onComplete = options.onComplete;
    options.onComplete = function(request) {
      element.update(request.transport.responseText);
      if (Object.isFunction(onComplete)) onComplete(request);
    };
    return $(element).callback(eventName, value, options);
  }
});