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Date: Wed, 16 Feb 2011 00:01:07 +0100
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Subject: Re: Struts application used as a web service (large number of
 sessions)
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Denis.Laroche@pwc.ca wrote:
> Hello everybody,
> 
> I wrote a Struts application deployed on a Tomcat server that is used as a 
> web service. What I see is that for every request sent by the client 
> applications a new session is created; I guess this is because there's no 
> JSESSIONID cookie sent with the request. Could someone tell me if it's 
> terribly inefficient for the server to have to create a new session for 
> every request? I could reduce the session timeout to the minimum, but the 
> application is also used by interactive users so the session timeout needs 
> to have a reasonable value.
> 
HttpSession (HttpRequest.)getSession() :
  Returns the current session associated with this request, or if the request does not 
have a session, creates one.

HttpSession : 
http://tomcat.apache.org/tomcat-5.5-doc/servletapi/javax/servlet/http/HttpSession.html

A session is created when there is a call to getSession().
No call to getSession(), no session.

In the big scheme of things, from the above descriptions, I would tend to think that a 
"session object" is not something trivial, so creating one when you don't need it is 
probably indeed quite inefficient.
(And then the session has to be stored somewhere, which will involve serialization, I/O 
etc..; and then some background task still has to periodically go clean up these useless 
sessions).

 From your description, it seems as if there are two types of usage of the same application :
- a usage by real users, which does require a session
- a usage as a web service, which does not require a session
   (because these are one-off calls, probably)

I don't know Struts at all, but is it possible to distinguish the two types of usage, and 
bypass the getSession() call when the application is used as a web service ?

Otherwise, would it be possible to set up two instances of your application ?
Such as :
/webapp1 : used by interactive users
/webapp2 : used by web service clients
and remove the getSession() call in the one used as a web service ?

Now again, inefficiency is a relative concept.
If your server is 50% idle anyway, you do not really want to spend a lot of time bringing 
it to 60% idle.

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