Using feedback control approach to guarantee QoS issues in mapserver

Currently, the Web Services has been increasing more and more popular on Internet. In recent years, the issue of quality of services (QoS) has become the major research focus, especially for the next generation of Internet frameworks. QoS problem is the delay of response time. There are two major technologies under the QoS framework, including services and differentiated services. The WebGIS Quality of Service (QoS) control should be deployed in WebGIS application servers (mapserver) in order to meet different requirements from clients and applications. In this paper, we use classical feedback control theory, i.e. the delay guarantee to contribute a QoS guarantee method to guarantee the QoS issue in mapserver. The delay guarantee includes absolutely delay guarantee and relative delay guarantee. The delay guarantee is designed to ensure that the average queuing delay for the requests with high priority is no more than the threshold configured.