Error in DataSource.getConnection() !

Question

Hello to u all,
I'm trying to make an application that uses database connection pooling and i've followed
closely the tutorial:
http://jakarta.apache.org/tomcat/tomcat-4.1-doc/printer/jndi-datasource-examples-howto.html
The code in the tutorial worked just fine, however, later when i tried to use it in my (servlet)application a get an error in the datasource.getconnection! Here's my code:
web.xml
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
<description>MySQL Test App</description>
<resource-ref>
<description>DB Connection</description>
<res-ref-name>jdbc/TestDB</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
<servlet>
<servlet-name>ServletContactosControllerDB</servlet-name>
<servlet-class>ServletContactosControllerDB</servlet-class>
<init-param>
     <param-name>event</param-name>
     <param-value>event</param-value>
     </init-param>
     <init-param>
     <param-name>error_event</param-name>
     <param-value>error</param-value>
     </init-param>
     <init-param>
     <param-name>new_user_event</param-name>
     <param-value>newuser</param-value>
     </init-param>
     <init-param>
     <param-name>dbLookup</param-name>
     <param-value>java:comp/env/jdbc/DBContactos</param-value>
     </init-param>
          <init-param>
     <param-name>login_event</param-name>
     <param-value>login</param-value>
     </init-param>
</servlet>
<servlet-mapping>
<servlet-name>ServletContactosControllerDB</servlet-name>
<url-pattern>/index.html</url-pattern>
</servlet-mapping>
</web-app>
I know that the configuration in the server.xml is fine because the example in the tutorial worked!!
so my code in the doPost method in the servlet is:
     Context initCtx = new InitialContext();
DebugUtility.println("POST 2 ");
DataSource dataSource = (DataSource)initCtx.lookup("java:comp/env/jdbc/TestDB");
DebugUtility.println("POST 3 ");
Connection con = dataSource.getConnection();
                    DebugUtility.println("POST 4");
it fails in getconnection with the following error:
Cannot create JDBC driver of class '' for connect URL 'null'
can anyone figure it out what is happening ? Is my web.xml with a wrong configuration !!
thx in advance to all of u !

Answer 1

Finally i have discover the error !!!
In fact the error reports some irony cause i had said with conviction that
the error wasn't in the server.xml , but it was :
<Context path="/contactos_sb" docBase="contactos_sb"
debug="5" reloadable="true" crossContext="true">
i was keeping the tutorial path and not my application path so my servlet wasn't able
to get the class driver and the url !!
So. it works fine now ! :)�