Tomcat error when using data source.

Question

Hello,
I have a problem in that Tomcat does not seem to be recognising my DB Driver. I have tried linking a global data source to my application as well as adding a project specific one with no luck. Here is some of my files:
//Web.xml
<?xml version='1.0' encoding='UTF-8'?>
<web-app
version="2.4"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_4.xsd"
>
<display-name>DataSourceExample</display-name>
<servlet>
<display-name>welcome</display-name>
<servlet-name>welcome</servlet-name>
<jsp-file>/welcome.jsp</jsp-file>
</servlet>
<servlet>
<display-name>DataSourceExample</display-name>
<servlet-name>DataSourceExample</servlet-name>
<jsp-file>/DataSourceExample.jsp</jsp-file>
</servlet>
<welcome-file-list>
<welcome-file>welcome.jsp</welcome-file>
</welcome-file-list>
<resource-ref>
<res-ref-name>jdbc/DataSourceExample</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
<res-sharing-scope>Shareable</res-sharing-scope>
</resource-ref>
</web-app>
//server.xml
<?xml version="1.0" encoding="UTF-8"?>
<Server>
  <Listener className="org.apache.catalina.core.AprLifecycleListener"/>
  <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener"/>
  <Listener className="org.apache.catalina.storeconfig.StoreConfigLifecycleListener"/>
  <Listener className="org.apache.catalina.mbeans.ServerLifecycleListener"/>
  <GlobalNamingResources>
    <Environment
      name="simpleValue"
      type="java.lang.Integer"
      value="30"/>
    <Resource
      name="jdbc/DataSourceExample"
      type="javax.sql.DataSource"
      maxActive="4"
      maxIdle="2"
      username="hr"
      maxWait="5000"
      driverClassName="oracle.jdbc.driver.OracleDriver"
      password="secret"
      url="jdbc:oracle:thin:@127.0.0.1:1521:xe"/>
    <Resource
      auth="Container"
      description="User database that can be updated and saved"
      name="UserDatabase"
      type="org.apache.catalina.UserDatabase"
      factory="org.apache.catalina.users.MemoryUserDatabaseFactory"
      pathname="conf/tomcat-users.xml"/>
  </GlobalNamingResources>
  <Service
      name="Catalina">
    <Connector
        port="8084"
        redirectPort="8443"
        minSpareThreads="25"
        connectionTimeout="20000"
        maxThreads="150"
        maxSpareThreads="75">
    </Connector>
    <Connector
        port="8009"
        redirectPort="8443"
        protocol="AJP/1.3">
    </Connector>
    <Engine
        defaultHost="localhost"
        name="Catalina">
      <Realm className="org.apache.catalina.realm.UserDatabaseRealm"/>
      <Host
          appBase="webapps"
          name="localhost">
         <Context
            path="/DataSourceExample"
          <ResourceLink
            global="jdbc/DataSourceExample"
            name="jdbc/DataSourceExample"
            type="javax.sql.DataSource"/>
        </Context>
      </Host>
    </Engine>
  </Service>
</Server>
//A java snippet I am using to access the DB
InitialContext context = new InitialContext();
DataSource dataSource =
(DataSource) context.lookup("java:comp/env/jdbc/DataSourceExample");
Connection conn = null;
Statement stmt = null;
ResultSet rset = null;
try {
conn = dataSource.getConnection();
stmt = conn.createStatement();I also have my DB drivers in the commons/lib file. I know the connect string works fine because I can access the DB from Eclipse when writing standard Java code.
This is a common problem and I have been searching Google for the last 3 hours but nothing I have tried has fixed my problem.
I am using Tomcat 5.5 and J2EE 5. I am creating the links and resources in Tomcat manager.
I don't get any logs or stacktrace, the only error I get is as follows in the returned JSP page:
DataSource Example
Cannot create JDBC driver of class '' for connect URL 'null'What am I doing wrong?
Cheers
EDIT:
Actually there was some output from the shell. Here it is:
org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of cla
ss '' for connect URL 'null'
        at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDat
aSource.java:780)
        at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSo
urce.java:540)
        at org.apache.jsp.DataSourceExample_jsp._jspService(DataSourceExample_js
p.java:61)
        at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
        at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper
.java:332)
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:3
14)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:252)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:173)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperV
alve.java:213)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextV
alve.java:178)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.j
ava:126)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.j
ava:105)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineVal
ve.java:107)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.jav
a:148)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java
:869)
        at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.p
rocessConnection(Http11BaseProtocol.java:664)
        at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpo
int.java:527)
        at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFol
lowerWorkerThread.java:80)
        at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadP
ool.java:684)
        at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.NullPointerException
        at sun.jdbc.odbc.JdbcOdbcDriver.getProtocol(JdbcOdbcDriver.java:507)
        at sun.jdbc.odbc.JdbcOdbcDriver.knownURL(JdbcOdbcDriver.java:476)
        at sun.jdbc.odbc.JdbcOdbcDriver.acceptsURL(JdbcOdbcDriver.java:307)
        at java.sql.DriverManager.getDriver(DriverManager.java:253)
        at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDat
aSource.java:773)
        ... 22 more
org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of cla
ss '' for connect URL 'null'
        at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDat
aSource.java:780)
        at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSo
urce.java:540)
        at org.apache.jsp.DataSourceExample_jsp._jspService(DataSourceExample_js
p.java:61)
        at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
        at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper
.java:332)
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:3
14)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:252)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:173)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperV
alve.java:213)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextV
alve.java:178)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.j
ava:126)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.j
ava:105)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineVal
ve.java:107)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.jav
a:148)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java
:869)
        at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.p
rocessConnection(Http11BaseProtocol.java:664)
        at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpo
int.java:527)
        at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFol
lowerWorkerThread.java:80)
        at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadP
ool.java:684)
        at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.NullPointerException
        at sun.jdbc.odbc.JdbcOdbcDriver.getProtocol(JdbcOdbcDriver.java:507)
        at sun.jdbc.odbc.JdbcOdbcDriver.knownURL(JdbcOdbcDriver.java:476)
        at sun.jdbc.odbc.JdbcOdbcDriver.acceptsURL(JdbcOdbcDriver.java:307)
        at java.sql.DriverManager.getDriver(DriverManager.java:253)
        at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDat
aSource.java:773)
        ... 22 moreI am using ojdbc14.jar driver and as I mentioned it is in commons/lib
Message was edited by:
helloWorld
Message was edited by:
helloWorld

Answer 1

Putting the driver into [TOMCAT]/common/lib is sufficient.
The error I think is not related to finding the driver, but actually not retrieving the correct connection string info.
I never had much luck putting this definition info into server.xml
I have had success putting it into a custom context.xml file for a web app as described [url http://tomcat.apache.org/tomcat-5.5-doc/config/context.html]here
in individual files (with a ".xml" extension) in the $CATALINA_HOME/conf/[enginename]/[hostname]/ directory. The name of the file (less the .xml) extension will be used as the context path. Multi-level context paths may be defined using #, e.g. context#path.xml. The default web application may be defined by using a file called ROOT.xml.
eg [TOMCAT]/conf/catalina/localhost/DataSourceExample.xml
Hope this helps,
evnafets