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Session simply means a particular interval of time.
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Session Tracking is a way to maintain state (data) of an user. It is also known as session management in servlet.
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HTTP and Web Server both are stateless, the only way to maintain a session is when some unique information about the session (session id) is passed between server and client in every request and response.
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Session Tracking Mechanism:
- Cookies
- Hidden Form Field
- URL Rewriting
- Session Management API.
- A cookie is a small piece of information that is persisted between the multiple client requests.
response.setContentType("text/html");
PrintWriter pw = response.getWriter();
Cookie = new Cookie(“name",“Suneet");
cookie.setMaxAge(60*60); //1 hour
response.addCookie(cookie);
pw.println("Cookie is created");
Session Management – Hidden Form Field
- A hidden (invisible) textfield is used for maintaining the state of an user.
<input type="hidden" name="userName" value=“Suneet">
- With URL rewriting, every local URL the user might click on is dynamically modified, or rewritten, to include extra information.
- We can send parameter name/value pairs using the following format:
url?name1=value1&name2=value2&??
- Container creates a session id for each user.
- The container uses this id to identify the particular user.
HttpSession session=request.getSession();
session.setAttribute("userName", “Suneet");