A design of WSD (Web Server Director) to throttle overloaded web server behavior is the major work of this thesis. Without modification of the backend web server, WSD controls and manages web requests to connect web server. Also, WSD verifies the correctness of web request header as a layer-7 web switch. WSD is the single process and non-blocking I/O model that is robust for overloaded requests. Therefore, WSD improves the performance of Apache web server by up to 1.6 times and protects the overload of the backend web server. Another useful side effect is that WSD defends SYN flood attacks and malicious requests. In fact, since WSD is an architecture of a layer-7 switch that is functionally equivalent to an application level proxy, clients have redundant connections between WSD and a web server. But it maintains low latency time by slim I/O implementation. Using a well known web benchmark, WSD is clearly demonstrated its robustness for overloaded web requests.
