Core Java Interview Questions And Answers

Question: What is a Session?
Answer: A Session refers to all the request that a single client makes to a server. A session is specific to the user and for each user a new session is created to track all the request from that user. Every user has a separate session and separate session variable is associated with that session. In case of web applications the default time-out value for session variable is 20 minutes, which can be changed as per the requirement.

Question: What is Session ID?
Answer: A session ID is an unique identification string usually a long, random and alpha-numeric string, that is transmitted between the client and the server. Session IDs are usually stored in the cookies, URLs (in case url rewriting) and hidden fields of Web pages. 

Question: What is Session Tracking?
Answer: HTTP is stateless protocol and it does not maintain the client state. But there exist a mechanism called "Session Tracking" which helps the servers to maintain the state to track the series of requests from the same user across some period of time. 

 Question: What  are different types of Session Tracking? 

 Answer: Mechanism for Session Tracking are:
               a) Cookies
               b) URL rewriting
               c) Hidden form fields
               d) SSL Sessions

 Question: What is HTTPSession Class? 

 Answer: HTTPSession Class provides a way to identify a user across across multiple request. The servlet container uses HttpSession interface to create a session between an HTTP client and an HTTP server. The session lives only for a specified time period, across more than one connection or page request from the user.