As a starting point ,is it right to state that to keep a
servlet 'thread-safe' I should stay away from having servlet
class variables? Else I would have to worry about locking
those variables when I use them in my servlet... Right?
How 'bout my database connections? If I use a connection
pool, as described in many serlet books, am I then
'thread-safe'?
Carlos Herrera
[EMAIL PROTECTED]
At 12:40 18/10/99 -0500, Li Xu wrote:
>there's been some discussion about servlet session these days on this mailing
>list. I am confused with the difference between session and thread. Can
anybody
>explain it to me?
They are not really connected. A thread is a Java thread - a single thread
of execution taken by a program - and is not specific to servlets. A
session is a means of associating requests from the same browser.
There will normally only be one instance of your servlet class created, and
for each connection to it from a browser, a different thread is used
(normally from a pool of threads). That means the same object may be being
used by multiple different threads at the same time (hence the requirement
to keep your servlets 'thread-safe' - i.e, stop one thread from trampling
on another's data).
A session, as mentioned, is a means of associating requests from the same
browser. HTTP is a stateless protocol, which means in simple language that
you issue a request, get a response and that's it. If you issue another
request, it doesn't know anything about the previous one. But in real world
use, particularly for things like e-commerce, you want to be able to have a
series of related transactions. A session is a means of doing this.
Normally by sending back a cookie to your browser, your servlet engine is
able to have the concept of a group of related requests.
Hope this helps!
John Moore
==================================================
John Moore ~ Norwich, UK ~ [EMAIL PROTECTED]
==================================================
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