ClassCastException when using BasicDataSource

["Tuncay Baskan (İnternet Grubu)" <Tu...@intertech.com.tr>]

I'm trying to use a JNDI name for a JDBC resource. Configuration is
as follows:

Tomcat 4.0.3
DBCP 1.0

In the server.xml, I have the following DefaultContext entry. (It must be
DefaultContext because there are 3 other webapps that use the same database)

<DefaultContext>
<Resource auth="Container" name="jdbc/eproject"
type="javax.sql.DataSource"/>
          
<ResourceParams name="jdbc/eproject">
<parameter>
  <name>factory</name>
  <value>org.apache.commons.dbcp.BasicDataSourceFactory</value></parameter>
<parameter>
  <name>validationQuery</name>  
  <value>select * from groups</value></parameter>
<parameter>
  <name>maxWait</name>          
  <value>10000</value></parameter>
<parameter>
  <name>maxActive</name>        
  <value>100</value></parameter>
<parameter>
  <name>username</name>
  <value>username</value></parameter>
<parameter>
  <name>password</name>         
  <value>password</value></parameter>
<parameter>
  <name>url</name>
  <value>jdbc:mysql://quantranet:3306/eproject?autoReconnet=true</value>
</parameter>
<parameter>
  <name>driverClassName</name>  
  <value>org.gjt.mm.mysql.Driver</value></parameter>
<parameter>
  <name>maxIdle</name>
  <value>30</value></parameter>
</ResourceParams>
</DefaultContext>

And in the web.xml:

<resource-ref id="ResourceRef_1039888737098">
  <description>none</description>
  <res-ref-name>jdbc/eproject</res-ref-name>
  <res-type>javax.sql.DataSource</res-type>
  <res-auth>Container</res-auth>
</resource-ref>

I think there isn't a problem with JNDI. jndiContext.lookup() calls
successfully return an "object". It returns the correct object, which is
BasicDataSource (a class that implements javax.sql.DataSource).

I re-evaluated the code, so jndi.lookup() returns an object that has the 
name "org.apache.commons.dbcp.BasicDataSource" which implements the 
javax.sql.DataSource interface. But... I don't know how, I'm getting
a ClassCastException when I cast it to DataSource to get a connection!
(btw, returned object is not an "instanceof" javax.sql.DataSource,
but getClass().getInterfaces() has javax.sql.DataSource)

    initContext = new InitialContext();
    envContext  = (Context)initContext.lookup("java:/comp/env");
    DataSource ds = (DataSource)envContext.lookup("jdbc/eproject");

or,

    initContext = new InitialContext();
    envContext  = (DataSource)initContext.lookup
                                    ("java:/comp/env/jdbc/eproject");

fails on the lines which I'm trying to cast DataSource.

So, how can it be? I really appreciate the one who can tell me why!

PS: commons-collections, commons-dbcp, commons-pool is in 
%CATALINA_HOME%\common\lib along with mysql-connector and they are in .jar
format as described in JNDI-Resources HOWTO.

/tb.