HTTP Session

Internal

• HTTP
• Servlet

Overview

HTTP is a stateless protocol and maintaining a conversational state of the server is not directly supported by the protocol. HTTP provides no build-in way for a server to recognize that a sequence of requests originate from the same user. Since CGI, developers have been using various techinques to track the session: user authentication, hidden form fields, URL rewriting and persistent cookies. The servlet API brings improved support for session tracking. The support is built in top of the traditional techniques and it simplifies the task of session tracking in your servlets.

Example

A HTTP Session Servlet https://github.com/NovaOrdis/playground/tree/master/jee/servlet/session-servlet

Methods to Maintain a HTTP Session

Methods to Maintain a HTTP Session

Servlet Session Tracking API

Servlet Session Tracking API

Session Implementation Details

JBossWeb/Tomcat HTTP Session Implementation Details

Browser/Server Conversation on Session Establishment

The first HTTP response that initiates the session and plants the cookie on the browser:

HTTP/1.x 200 OK
Date: Thu, 22 Oct 2009 14:17:28 GMT
Server: Apache/2.2.6 (Unix) mod_ssl/2.2.6 a/journals/zihuatanejo.html$ mod_jk/1.2.26
X-Powered-By: Servlet 2.4; JBoss-4.0.5.GA (build: CVSTag=Branch_4_0 date=200610162339)/Tomcat-5.5
Set-Cookie: JSESSIONID=71867A63768B13C9B58E623401BE7C57.tastcomapp01; Path=/
Cache-Control: no-cache
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Transfer-Encoding: chunked
Content-Type: text/html;charset=UTF-8

In the example above, the session cookie is JSESSIONID and the session ID is 71867A63768B13C9B58E623401BE7C57.tastcomapp01.

Subsequent HTTP requests include the session id as a header:

GET /thirdpartyheaderarray HTTP/1.1
Host: 10.58.128.48
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3
Accept: */*
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Referer: http://10.58.128.48/
Cookie: JSESSIONID=71867A63768B13C9B58E623401BE7C57.tastcomapp01

Session Timeout

HTTP Session Timeout