SESSION related Questions

[Simran Dass]

I have confusion in the foll questions ( from Marcus Green).

State whether true or false :-


1) A session will always be invalidated if a user shuts down his browser.

2) A session will always be invalidated if the servlet container restarts.

3) Data in a HttpSession attribute will not be available if the web server restarts.


According to me , A and B should be TRUE
C should be FALSE

Am I right ? If any of my answer is wrong could you please explain why.

Please help , I plan to give the exam in next 15 days.

[Frits Walraven]

Hi Simran,

All the answers should be false, here my explanations:

1) A session will always be invalidated if a user shuts down his browser.

The server doesn't know that the browser (client) has gone, so it won't invalidate the session. It will only be invalidated after a session-timeout

2) A session will always be invalidated if the servlet container restarts.

Some servlet-containers store their sessions on disk when there is a system-failure or close down.

3) Data in a HttpSession attribute will not be available if the web server restarts.

Because of the previous answer the data could be recovered from disk. However all attributes put into the session object should then be Serializable.

Regards,
Frits

[Simran Dass]

Thanks a lot Frits .

Say we remove the word always from this sentence and have may/might instead i.e. -

" A session might be invalidated if the servlet container restarts " then will it be true bec' some containers might not store a session on disk.

[Frits Walraven]

Correct!

Be very keen on those words during your exam.

Regards,
Frits

[Nidhi Sar]

When I try it out on my computer - restart the tomcat service and then access the various attributes - the session attribute value is still available (though the application attributes have been lost ofcourse).

So is this container dependent or will the session object always exist, till it times out or is invalidated?

[Frits Walraven]

Hi Nidhi,

So is this container dependent or will the session object always exist, till it times out or is invalidated?

As it is nowhere mentioned in the servlet spec that a session object should survive a system-failure or close down you can say that it is container dependent

Regards,
Frits