An Adaptive Hierarchy Management System for Web Caches

A group of web caches can be organized into a cooperative hierarchy where a search for a requested object is performed among the cooperating peer caches before the object request is sent to the origin web server. Such cooperation improves the overall hit ratio but introduces the overhead of an additional step in request processing as well as additional workload on the caches and more traffic in the network. The main goal of cooperation is to improve the response time observed by clients, but the result can be the opposite, if, e.g., the network between the caches is very busy. In this paper, we present an Adaptive Hierarchy Management System to dynamically configure a hierarchy of caches based on existing conditions, without human intervention. The system consists of a centralized controller and distributed agents installed on the caches. The agents collect and report information on cache usage. The controller monitors the underlying network and determines the best hierarchy based on cache and network information. The new hierarchy is then broadcast to all agents. The agents deploy the new hierarchy by reconfiguring the caches. The optimal hierarchy is based on the available bandwidth on the links between the caches and the inter-cache hit ratio. The system was validated by processing web traces on a Squid cache hierarchy. Performance improvement of up to 30% was observed with an adaptive hierarchy under varying network conditions

An Adaptive Hierarchy Management System for Web Caches

A group of web caches can be organized into a cooperative hierarchy where a search for a requested object is performed among the cooperating peer caches before the object request is sent to the origin web server. Such cooperation improves the overall hit ratio but introduces the overhead of an additional step in request processing as well as additional workload on the caches and more traffic in the network. The main goal of cooperation is to improve the response time observed by clients, but the result can be the opposite, if, e.g., the network between the caches is very busy. In this paper, we present an Adaptive Hierarchy Management System to dynamically configure a hierarchy of caches based on existing conditions, without human intervention. The system consists of a centralized controller and distributed agents installed on the caches. The agents collect and report information on cache usage. The controller monitors the underlying network and determines the best hierarchy based on cache and network information. The new hierarchy is then broadcast to all agents. The agents deploy the new hierarchy by reconfiguring the caches. The optimal hierarchy is based on the available bandwidth on the links between the caches and the inter-cache hit ratio. The system was validated by processing web traces on a Squid cache hierarchy. Performance improvement of up to 30 % was observed with an adaptive hierarchy under varying network conditions