According to the doc "JNDI Datasource HOW-TO", i setup the connection pool 
using DBCP, everything is the same as what the doc shows except for the oracle 
sid and user/pass.
But when i boot up tomcat, something happened.
The page which use sql select is correct while if i use sql update function a 
OracleXMLSQLException occured, Which is caused by class cast i think.
The sql statement including select,insert,update and delete all implemented 
with xdk for oracle.



the logfile shows:
StandardWrapperValve[Login]: Servlet.service() for servlet Login threw exception
oracle.xml.sql.OracleXMLSQLException: java.lang.ClassCastException
	at oracle.xml.sql.dml.OracleXMLSave.saveXML(OracleXMLSave.java:2088)
	at oracle.xml.sql.dml.OracleXMLSave.updateXML(OracleXMLSave.java:1443)
	at XMLBean.execute(XMLBean.java:101)
	at ControlBean.setTime(ControlBean.java:491)
	at Login._jspService(Login.java:184)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:136)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter
(ApplicationFilterChain.java:247)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter
(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.StandardWrapperValve.invoke
(StandardWrapperValve.java:260)
	at 
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNex
t(StandardPipeline.java:643)
	at org.apache.catalina.core.StandardPipeline.invoke
(StandardPipeline.java:480)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
	at org.apache.catalina.core.StandardContextValve.invoke
(StandardContextValve.java:191)
	at 
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNex
t(StandardPipeline.java:643)
	at org.apache.catalina.core.StandardPipeline.invoke
(StandardPipeline.java:480)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
	at org.apache.catalina.core.StandardContext.invoke
(StandardContext.java:2396)
	at org.apache.catalina.core.StandardHostValve.invoke
(StandardHostValve.java:180)
	at 
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNex
t(StandardPipeline.java:643)
	at org.apache.catalina.valves.ErrorDispatcherValve.invoke
(ErrorDispatcherValve.java:170)
	at 
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNex
t(StandardPipeline.java:641)
	at org.apache.catalina.valves.ErrorReportValve.invoke
(ErrorReportValve.java:172)
	at 
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNex
t(StandardPipeline.java:641)
	at org.apache.catalina.valves.AccessLogValve.invoke
(AccessLogValve.java:469)
	at 
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNex
t(StandardPipeline.java:641)
	at org.apache.catalina.core.StandardPipeline.invoke
(StandardPipeline.java:480)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
	at org.apache.catalina.core.StandardEngineValve.invoke
(StandardEngineValve.java:174)
	at 
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNex
t(StandardPipeline.java:643)
	at org.apache.catalina.core.StandardPipeline.invoke
(StandardPipeline.java:480)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
	at org.apache.catalina.connector.http.HttpProcessor.process
(HttpProcessor.java:1040)
	at org.apache.catalina.connector.http.HttpProcessor.run
(HttpProcessor.java:1151)
	at java.lang.Thread.run(Thread.java:536)

the 101 line of XMLBean.java is  s.updateXML(Doc), s is a instance of 
OracleXMLSave and Doc is a string.