Replication of information among multiple Web servers is necessary to support high request rates to popular Web sires. A clustered Web-server organization is preferable to multiple independent mirrored-servers because it maintains a single interface to the users and has the potential to be more scalable, fault-tolerant and better load balanced. In this paper we propose a Web cluster architecture in which the Domain Name System sen er (DNS), that dispatches the user requests among the servers through the URL-name to IP-address mapping mechanism, is integrated with a redirection request mechanism based on the HTTP protocol. This should alleviate the side effect of caching the IP-address mapping at intermediate name servers. We compare many alternative mechanisms, including synchronous vs asynchronous activation, and centralized vs distributed decision on redirection. Moreover, we analyze reassignment of entire domains or individual client requests, different types of status information, and different sen er selection policies for redirecting requests. Our results show that the combination of centralized and distributed dispatching policies allows the Web-server cluster to handle the high loan skews in the WWW environment.
Cardellini, V., Colajanni, M., Yu, P. (1999). Redirection algorithms for load sharing in distributed Web-server systems. In PROCEEDINGS OF 19TH IEEE INTERNATIONAL CONFERENCE ON DISTRIBUTED COMPUTING SYSTEMS (pp.528-535). LOS ALAMITOS : IEEE COMPUTER SOC [10.1109/ICDCS.1999.776555].
Redirection algorithms for load sharing in distributed Web-server systems
CARDELLINI, VALERIA;
1999-01-01
Abstract
Replication of information among multiple Web servers is necessary to support high request rates to popular Web sires. A clustered Web-server organization is preferable to multiple independent mirrored-servers because it maintains a single interface to the users and has the potential to be more scalable, fault-tolerant and better load balanced. In this paper we propose a Web cluster architecture in which the Domain Name System sen er (DNS), that dispatches the user requests among the servers through the URL-name to IP-address mapping mechanism, is integrated with a redirection request mechanism based on the HTTP protocol. This should alleviate the side effect of caching the IP-address mapping at intermediate name servers. We compare many alternative mechanisms, including synchronous vs asynchronous activation, and centralized vs distributed decision on redirection. Moreover, we analyze reassignment of entire domains or individual client requests, different types of status information, and different sen er selection policies for redirecting requests. Our results show that the combination of centralized and distributed dispatching policies allows the Web-server cluster to handle the high loan skews in the WWW environment.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
