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J2EE application giving exeptions in multiuser mode

 
Shyam kumar
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Hi Ranchers,

We are developing an Web based online test system that allows multiple candidates to give the test simultaneusly.We have used stateless session bean in which there are methods like submitQuestion, retrieveAsnswerSheet . For accessing the database we are using a DBAccess class that makes the connection to the database and fires the query and returns the resultset. We call this DbAccess class from session bean, The problem is that the system is working fine when executed in single user mode, but as the no. of users increases (say 10) We start getting the following exeptions, that are related to parameter binding in prepared statement, some times it will not able to pass values to query:



java.sql.SQLException: [Microsoft][SQLServer 2000 Driver for JDBC]Object has been closed.

java.sql.SQLException: [Microsoft][SQLServer 2000 Driver for JDBC]Invalid parameter binding(s).

java.lang.NullPointerException

java.lang.StringIndexOutOfBoundsException: String index out of range: -1



Can anyone please comment as to why this application is failing in multiuser mode?

Thanks in advance.
 
Vinay Raj
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Check if you are using the same connection object across multiple user sessions.
 
Shyam kumar
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Hi Raj,

We are using Websphere application server poooling. We are closing the connection in every method of stateless session bean.

Thanks
 
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