The invention discloses a method for processing at least one event in a Web-based application system. The method comprises the steps of receiving a request and activating a sub-window in a main window for the request; assigning an ID for the request; setting a time interval for the request; specifying a result storage location for the request according to the assigned ID; allotting a service routine for the request; processing the request by using the service routine; storing the processing result in the specified result storage location; polling arrival of processing results at the time interval; and displaying the processing result. This method can be used for processing two and more requests concurrently by considering restrictive relationships thereof. The method may further transfer the request to the backbone application service and listen to the reply therefrom. The method may further display processing statuses in real time in addition to the process result. The present invention also provides a web-based application supporting system and a web-based application system using the above method.