Is session id machine independent and unique?

[Matt]

I want to understand if session id is unique in a machine? For example, if I open
5 different web sites in 5 web browsers, I should get 5 unique session ids
for each browser. However, the session id I get in machine A can be
the same as in machine B? I think session Id is generated by the web server?
And how session id is generated?

Please advise. Thanks

 

[Andy Flowers]

The format of a Session Id is AFAIK unique to each and every vendor.

Session Ids have the possibility to be reused though. If the session on
machine A times out then that id could be regenerated for machine B. One
this that should be true, however, is that not 2 distinct sessions, whether
from different browser sessions on a single machine or different machines,
should have the same session Id at the same point in time.

To get a handle on how it 'could' be implemented why not take a look at the
Tomcat source code/documentation and havea look at how it handles sessions ?
http://jakarta.apache.org/tomcat/index.html

 

[marcus]

or better yet, learn to read

"Returns a string containing the unique identifier assigned to this
session. The identifier is assigned by the servlet container and is
implementation dependent."

this is not hard.