Implementation of absolute delay guarantee in databaseconnection pool in Web application servers
绝对延迟保证在Web应用服务器数据库连接池中的实现

Network QoS mechanisms are insufficient to provide complete end to end performance guarantees. In e-commerce Web sites composed of a three-tiered architecture, this paper proposed and implemented absolute delay guarantee in the database connection pool(DBCP)in Web application servers based on feedback control. It improved the database connection pool to ensure that the response time for requests with high priority was no more than the threshold specified. It set up the approximate linear time-invariant models of the DBCP through system identification and designed the absolute delay guarantee controller. It implemented all the components of closed-loops in a real DBCP for the Tomcat Web application server. Test results show that the controllers designing is effectively even if the number of concurrent requests varies severely.