HTTP and Sessions The HTTP protocol is connectionless That is,once the server replies to a request,the server closes the connection with the client,and forgets all about the request In contrast,Unix logins,and JDBC/ODBC connections stay connected until the client disconnects retaining user authentication and other information Motivation:reduces load on server operating systems have tight limits on number of open connections on a machine Information services need session information E.g.,user authentication should be done only once per session Solution:use a cookie Database System Concepts-7th Edition 9.14 ©Silberscha乜，Korth and SudarshanDatabase System Concepts - 7 9.14 ©Silberschatz, Korth and Sudarshan th Edition HTTP and Sessions ▪ The HTTP protocol is connectionless • That is, once the server replies to a request, the server closes the connection with the client, and forgets all about the request • In contrast, Unix logins, and JDBC/ODBC connections stay connected until the client disconnects ▪ retaining user authentication and other information • Motivation: reduces load on server ▪ operating systems have tight limits on number of open connections on a machine ▪ Information services need session information • E.g., user authentication should be done only once per session ▪ Solution: use a cookie