Hight Available Cluster For HTTP Service

Today, computer network is under a rapid development, and servers in the network are required to provide much higher available serving. Many servings such e-commerce require 7x24 continuously be available, otherwise the serving broken down will mean a disaster. Using High Level mechine to meet the high availability will bring a high cost and be difficult to extend the server. Manager several low level computers as a cluster and provide redundance of hardware and software to avoid server failure is a easier and more cheaper way.Being a excellent open source operating system, Linux have been applied to servers. The article analyzes a open source cluter software "KTCPVS". The software is a implementation of a HTTP load balance cluster, which base on content. Base on KTCPVS project, the article give a design of "HA-HTTP", a cluster software for high availablity. In the HA-HTTP system, multiple servers run simultaneously, one server node failure almost does not impact the client, only if all server fail the serving will stop. Definitely HA-HTTP rise the server availablityTo avoild content switch between kernel and application, KTCPVS runs as a kernel module of Linux. This article introduces the basic knowledge of Linux kernel module programing, analizes the Linux network implementation relating to HA-HTTP.HA-HTTP is a software running in the front nod of a cluster, doing data switch. A issue for HA-HTTP to switch HTTP messages is to process the HTTP session. The article analyzes HTTP status management mechanism, gives details of using cookie to keep session status, gives a solution of how to switch data with status management information, and gives detail design for the software.At last, the article introduces measure and testing method of server availablity, and give a evaluatation for HA-HTTP cluster system.