Many overload control mechanisms for Web based applications aim to prevent overload by setting limits on factors such as admitted load, number of server threads, buffer size. For this they need online measurements of metrics such as response time, throughput, and resource utilization. This requires instrumentation of the server by modifying server code, which may not be feasible or desirable. An alternate approach is to use a proxy between the clients and servers. We have developed a proxy-based overload control platform called MASTH Proxy?Multi-class Admissioncontrolled Self-Tuning Http Proxy. It records detailed measurements, supports multiple request classes, manages queues of HTTP requests, provides tunable parameters and enables easy implementation of dynamic overload control. This gives designers of overload control schemes a platform where they can concentrate on developing the core control logic, without the need to modify upstream server code. Categories and Subject Descripto...