In this thesis, a new admission controller for providing fairness to users is pro-posed. In conventional cluster web server farm, admission controller is deployed in the front-end dispatcher to prevent overload of back-end server farms. Convention-al admission control schemes discards user requests when the number of pending requests exceeds a threshold. They do not guarantee user fairness.
The proposed admission controller, called Flattener, differentiates the users' re-quests based on the number of retries. A ticket is given to a client if the client's request is not admitted and the client sends request accompanied by the ticket in the next retry. The requests are classified into three classes and accepted based on their priority by the flatter. The lowest priority requests are the ones from the clients with no ticket. The middle priority requests are the ones from the clients with tickets and the requests are the first retries. The highest priority requests are the ones from the clients with tickets and the requests are more than two retries.
The proposed method is especially beneficial when the burst requests are arrived in a very short time period. Experimental results show that the web server using the proposed admission controller loses less clients than using the conventional admission controller.
