A CLUSTERING BASED WEB PREFETCHING IN HIGH TRAFFIC ENVIRONMENT

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A CLUSTERING BASED WEB PREFETCHING IN HIGH TRAFFIC ENVIRONMENT

 

 

CHAPTER ONE

INTRODUCTION

1.1         Background of Study

The web is a collection of text documents and other resources, linked by hyperlinks and Uniform Resource Locator (URLs), usually accessed by web browsers, from web servers. The web started from a simple information sharing system, and has now grown to a rich collection of dynamic and interactive services. The tremendous growth of web has resulted into high demand for high bandwidth and delay in fetching user request (Neha, 2013). Users sometimes experience unpredictable delay while retrieving web pages from the server. Increase in bandwidth is a possible solution to the problem but it involves high economic cost. Web caching reduces the latency perceived by the user, reduces bandwidth utilization and reduces the loads on the origin servers (Pallis, 2007). Latency refers to the time elapsed from the time a request is sent to the time sender receives the requested information.

Many latency tolerant techniques have been developed over the years to solve this problem without necessarily increasing the bandwidth. Most notably are caching and prefetching. Web prefetching helps to fetch and cache users request during server idle time, which will reduce the load on the origin server. To reduce the access delay experienced by users, it is advisable to predict and prefetch web object based on user access patterns and cache them. Studies on web pre-fetching are mostly based on the history of user access patterns. If the history information shows an access pattern of URL address A followed B with a high probability, then B will be prefetched once A is accessed (Cheng-Zhong, 2000).

Web prefetching is the process of obtaining web pages in advance by proxy server before a request is sent by a user. When a client makes a request for web object, rather than sending request to the web server, it may be fetched from the cache. The main factor for selecting a web pre-fetching algorithm is its ability to predict the web object to be prefetched in order to reduce latency. Web prefetching exploits the spatial locality of web pages, i.e. pages that are linked with current page will be accessed with higher probability than other pages. Web prefetching can be applied in a web environment as between clients and web server, between proxy servers and web server and between clients and proxy server (Greeshma, 2012).

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A CLUSTERING BASED WEB PREFETCHING IN HIGH TRAFFIC ENVIRONMENT