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Abstract

As cluster based Web servers are increasingly adopted to host a variety of network 

based services, performance improvement of these servers has become a critical issue.

Since user level communication is an effective technique to reduce the intra cluster com 

munication overhead, cluster based Web server design utilizing user level communication

mechanisms has been a popular research focus in recent times. In this context, the over 

all objective of this research is to explore several design issues in order to enhance the

performance of cluster based network servers based on user level communication mech 

anisms.

Due to their complexity, the performance of cluster based Web servers is depen 

dent on various design choices and demands imposed on the systems. Therefore, we

investigate several design issues with different system environments as explained below.

First, we propose a coscheduled server model, which coschedules the communication pro 

cesses of a request. Its main objective is to minimize the response time of requests that

need intra cluster communication. The coscheduled server is modeled using two known

coscheduling techniques, called Dynamic Coscheduling (DCS) and DCS with immediate

blocking. Second, we investigate the impact of the Secure Socket Layer (SSL) offer 

ing in cluster based application servers and propose a SSL backend forwarding scheme,

called SSL with bf. Although SSL is the most popular protocol to provide a secure chan 

nel between a client and an application server, its high overhead degrades the server

performance considerably, and thus, affects the server scalability. Therefore, improving