I have J2EE application running on OC4J application server. Where the database connection is dropping / resetting after some idle time. The idle time varies from 20 mins to 90 mins. The persistence layer is created using Spring and iBatis with Struts as controller.

I am not able to find that why the code / oracle database is trying to close the connection before it makes new one.

Here is the exception log:
[05 Oct 2009 11:55:38] DEBUG [SQLErrorCodesFactory] Looking up default SQLErrorCodes for DataSource [org.springframework.jdbc.datasource.TransactionAwareDataSourceProxy@13478c8]
[05 Oct 2009 11:55:38] DEBUG [DataSourceUtils] Fetching JDBC Connection from DataSource
[05 Oct 2009 11:55:38] DEBUG [DataSourceUtils] Fetching JDBC Connection from DataSource
[05 Oct 2009 11:55:38] DEBUG [DataSourceUtils] Returning JDBC Connection to DataSource
[05 Oct 2009 11:55:38] DEBUG [DataSourceUtils] Returning JDBC Connection to DataSource
[05 Oct 2009 11:55:38] DEBUG [SQLErrorCodesFactory] Database product name cached for DataSource [org.springframework.jdbc.datasource.TransactionAwareDataSourceProxy@13478c8]: name is 'Oracle'
[05 Oct 2009 11:55:38] DEBUG [SQLErrorCodesFactory] SQL error codes for 'Oracle' found
[05 Oct 2009 11:55:38] DEBUG [SQLErrorCodeSQLExceptionTranslator] Translating SQLException with SQL state '08006', error code '17002', message [  
--- The error occurred in org/nexweb/qol/gcc/ibatis/dao/xml/User.xml.  
--- The error occurred while applying a parameter map.  
--- Check the getUserByUserNameAndRealmName-InlineParameterMap.  
--- Check the statement (query failed).  
--- Cause: java.sql.SQLException: Io exception: Connection reset by peer: socket write error]; SQL was [] for task [SqlMapClient operation]
[05 Oct 2009 11:55:38] DEBUG [DataSourceUtils] Returning JDBC Connection to DataSource
[05 Oct 2009 11:55:38] DEBUG [UserSqlMapDAO] Could not close JDBC Connection
java.sql.SQLException: Already closed.
      at org.apache.commons.dbcp.PoolableConnection.close(PoolableConnection.java:84)
      at org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper.close(PoolingDataSource.java:181)
      at org.springframework.jdbc.datasource.DataSourceUtils.doReleaseConnection(DataSourceUtils.java:313)
      at org.springframework.jdbc.datasource.TransactionAwareDataSourceProxy$TransactionAwareInvocationHandler.invoke(TransactionAwareDataSourceProxy.java:166)
      at $Proxy0.close(Unknown Source)
      at org.springframework.orm.ibatis.SqlMapClientTemplate.execute(SqlMapClientTemplate.java:218)
      at org.springframework.orm.ibatis.SqlMapClientTemplate.queryForObject(SqlMapClientTemplate.java:271)
      at org.nexweb.qol.gcc.ibatis.dao.sqlmaps.UserSqlMapDAO.getUserByUserNameAndRealmName(UserSqlMapDAO.java:26)
      at org.nexweb.qol.gcc.ibatis.services.UserService.getUserByUserNameAndRealmName(UserService.java:30)
      at org.nexweb.qol.gcc.actions.WelcomeAction.execute(WelcomeAction.java:71)
      at org.apache.struts.chain.commands.servlet.ExecuteAction.execute(ExecuteAction.java:58)
      at org.apache.struts.chain.commands.AbstractExecuteAction.execute(AbstractExecuteAction.java:67)
      at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
      at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
      at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:304)
      at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
      at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
      at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
      at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:449)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:743)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
      at com.evermind.server.http.ServletRequestDispatcher.invoke(ServletRequestDispatcher.java:713)
      at com.evermind.server.http.ServletRequestDispatcher.forwardInternal(ServletRequestDispatcher.java:370)
      at com.evermind.server.http.ServletRequestDispatcher.unprivileged_forward(ServletRequestDispatcher.java:259)
      at com.evermind.server.http.ServletRequestDispatcher.access$100(ServletRequestDispatcher.java:51)
      at com.evermind.server.http.ServletRequestDispatcher$2.oc4jRun(ServletRequestDispatcher.java:193)
      at oracle.oc4j.security.OC4JSecurity.doPrivileged(OC4JSecurity.java:283)
      at com.evermind.server.http.ServletRequestDispatcher.forward(ServletRequestDispatcher.java:198)
      at com.evermind.server.http.EvermindPageContext.forward(EvermindPageContext.java:392)
      at _jsp._forward._jspService(_forward.java:48)
      at com.orionserver.http.OrionHttpJspPage.service(OrionHttpJspPage.java:59)
      at oracle.jsp.runtimev2.JspPageTable.service(JspPageTable.java:462)
      at oracle.jsp.runtimev2.JspServlet.internalService(JspServlet.java:594)
      at oracle.jsp.runtimev2.JspServlet.service(JspServlet.java:518)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
      at com.evermind.server.http.ServletRequestDispatcher.invoke(ServletRequestDispatcher.java:713)
      at com.evermind.server.http.ServletRequestDispatcher.forwardInternal(ServletRequestDispatcher.java:370)
      at com.evermind.server.http.HttpRequestHandler.doProcessRequest(HttpRequestHandler.java:871)
      at com.evermind.server.http.HttpRequestHandler.processRequest(HttpRequestHandler.java:453)
      at com.evermind.server.http.HttpRequestHandler.serveOneRequest(HttpRequestHandler.java:221)
      at com.evermind.server.http.HttpRequestHandler.run(HttpRequestHandler.java:122)
      at com.evermind.server.http.HttpRequestHandler.run(HttpRequestHandler.java:111)
      at oracle.oc4j.network.ServerSocketReadHandler$SafeRunnable.run(ServerSocketReadHandler.java:260)
      at com.evermind.util.ReleasableResourcePooledExecutor$MyWorker.run(ReleasableResourcePooledExecutor.java:303)
      at java.lang.Thread.run(Thread.java:595)

Here is the Spring.xml code related to datasource

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN"
		  "http://www.springframework.org/dtd/spring-beans-2.0.dtd">
<beans>
    <bean id="propertyConfigurer"
          class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="location" value="classpath:jdbc.properties"/>
    </bean>
 
    <bean id="dataSource"
          class=" org.apache.commons.dbcp.BasicDataSource">          
        <property name="driverClassName" value="${jdbc.driverClassName}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean> 
   
    <bean id="sqlMapClient"
          class="org.springframework.orm.ibatis.SqlMapClientFactoryBean">
        <property name="configLocation">
            <value>classpath:org/nexweb/qol/gcc/ibatis/config/SqlMapConfig.xml</value>
        </property>
 
        <property name="transactionConfigProperties">
          <props>
                <prop key="autoCommitAllowed">true</prop>
          </props>        
        </property> 
 
       <property name="useTransactionAwareDataSource">
            <value>true</value> 
       </property>
        <property name="transactionConfigClass">
            <value>com.ibatis.sqlmap.engine.transaction.jdbc.JdbcTransactionConfig</value>
        </property>
        <property name="dataSource" ref="dataSource"/> 
    </bean>