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From "Frank W. Zammetti" <>
Subject Re: creation of a common session variable.
Date Fri, 21 Sep 2007 13:15:08 GMT
Application context, or application scope, is well-suited to this need 
too... the overhead should be at least a little bit less than JNDI 
(maybe not much, I've never benchmarked it) and you'll be able to access 
this data for all clients globally (i.e., any request, any session).

One caveat: I believe it's left to the app server to decide if app 
context is replicated across multiple nodes in a cluster, so if you're 
in such an environment then this might not be a good answer.  Even 
multiple JVMs on the same server, I think, is still determined by the 
app server.  I'm not sure what Tomcat does in this regard, but if you 
ever move to another app server you might find your application breaks 
if you have multiple nodes.  For single server/JVM configurations it's 
not an issue though.


Dale Nesbitt wrote:
> Not sure, maybe somebody else would know.  But if there is a performance
> hit, it would be simple enough to just fetch the object once in your
> init() method then keep a reference to it.
> Pavan Singaraju wrote:
>> Thanks guys,
>> I have one more question. Using the JNDI, will it put any additional burden
>> on Tomcat webserver?? I mean performance wise?
>> --
>> Pavan S. Kumar
>> On 9/20/07, David Smith <> wrote:
>>> Another possibility is to store it in the ServletContext (ie application
>>> scope) if it's just used on one webapp.
>>> --David
>>> Dale Nesbitt wrote:
>> I believe you can load any JavaBean using JNDI, and the bean will be
>> shared between all sessions in the context.
>> Pavan Singaraju wrote:
>>>>>> Hi,
>>>>>>   i have a design related question. I have to maintain some data
>>>> to
>>>>>> all sessions. If one session updates the value in the data structure,
>>>> then
>>>>>> it should either updated in all the sessions / in the common data
>>>> structure.
>>>>>> Is there an approach i can go with?
>>>>>> --
>>>>>> Pavan S. Kumar

Frank W. Zammetti
Founder and Chief Software Architect
Omnytex Technologies
AIM/Yahoo: fzammetti
Author of "Practical Ajax Projects With Java Technology"
  (2006, Apress, ISBN 1-59059-695-1)
and "JavaScript, DOM Scripting and Ajax Projects"
  (2007, Apress, ISBN 1-59059-816-4)
Java Web Parts -
  Supplying the wheel, so you don't have to reinvent it!

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