195 Java web application to demonstrate Session Tracking using HttpSession with Cookies Part 1 | Se

Create Java web application to demonstrate Session Tracking / Handling using HttpSession with Cookies(Use More than 3 to 4 Servlets):
2 Diagram:
Explaination:
Steps for Flow of execution with respect to above diagram:
Step 1) The static form page personal.html gives request1 from browser window b1.

Step 2) FirstServlet prorgram of SessionApp web application receives request1 and reads personal.html/request1 data.

Step 3) This FirstServlet program creates HttpSession object on the server for browser window b1 to begin the session between browser window b1 and SessionApp web application.

Step 4) FirstServlet program (*1) keeps/writes personal.html/request1 data in HttpSession object as session attribute value's(name, address, age).
*a
(*a Here HttpSession object means its the object of underlaying container supplied java class that implements javax.servlet.http.HttpSession interface)
HttpSession object and its attributes are visible and accessible all web resource programs of web application.

Step 5) FirstServlet program gets the server generated session id of the HttpSession Object (3EBB39E658D2AA6CFF13AD4C3A5F033F)

Step 6) FirstServlet program generates response1 having form2 as dynamic form page. This response also contains the session id of the session object(b1) as in-memory cookie value so that session id related cookie allocates memory on browser window as shown above diagram.

Step 7) form2(dynamic form page) generates request2 to SecondServlet program of SessionApp web application. This request contains cookie that holds session id.(3EBB39E658D2AA6CFF13AD4C3A5F033F)

Step 8) SecondServlet program reads the form2 data and also reads session id from cookie.

Step 9) SecondServlet program (*2) keeps/writes form2/request2 data in HttpSession object as session attribute value's(experience,skills).

Step 10) SecondServlet program generates response2 having form3 as dynamic form page. This response also contains the session id of the session object(b1) as in-memory cookie value so that session id related cookie allocates memory on browser window as shown above diagram.

Step 11) form3(dynamic form page) generates request3 to ThirdServlet program of SessionApp web application. This request contains cookie that holds session id.(3EBB39E658D2AA6CFF13AD4C3A5F033F)

Step 12) ThirdServlet program reads the form3/request3 data and also reads session id from cookie.

Step 13) ThirdServlet program uses the session id collected from cookie of request3 to search, access HttpSession object of browser window b1 on the server and also reads its session attribute values which is nothing but form1/request1 data(name, address, age *1), form2/request2 data(experience, skills *2). That means ThirdServlet is able to get use of form1/request1, form2/request2 data while processing form3 generated request3 this is nothing but Session Handling/traking/management.

Step 14) ThirdServlet now can write form1/request1, form2/request2, form3/request3 data to database table as record.

Step 15) ThirdServlet generates dynamic webpage as response3 having form1 and form2, form3 data, if necessary it can also invalidate session by calling session.invalidate().


Conclusion:
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In this diagram FirstServlet program begins the session between browser window b1 and SessionApp web application by creating new HttpSession object on server, for browser window b1 and SecondServlet, ThirdServlet participate in that already(existing) created/available session for request2, request3 but ThirdServlet invalidate that session before response3 by calling session.invalidate() method.

In this web application(SessionApp) form1/request1 data, form2/request2 data are received by FirstServlet, SecondServlet respectively are placed in HttpSession object as session attribute values (*1, *2).

Form3/request3 data is given to ThirdServlet. This ThirdServlet is reading form1/request1, form2/request2 data from session object as session attribute values. That means ThirdServlet is able use request1, request2 data while processing request3. This is nothing but Session Tracking/handling/management.

Note:
If multiple browser windows are giving requests to a java web application on which HttpSession based Session tracking/handling is enabled then multiple HttpSession objects will be created on the server on One per browser window/client basis.

web application treats every browser window as a client but does not treat/behave TAB of browser window as a separate client.
(Upto here Part 1 )