A Three-Tier Application

<DefaultContext>
   <Resource name="jdbc/mydb" auth="Container" type="javax.sql.DataSource"/>
   <ResourceParams name="jdbc/mydb">
      <parameter>
         <name>factory</name>
         <value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
      </parameter>
      <parameter>
         <name>driverClassName</name>
         <value>driver class</value>
      </parameter>
      <parameter>
         <name>url</name>
         <value>database URL</value>
      </parameter>
      <parameter>
         <name>username</name>
         <value>database user name</value>
      </parameter>
      <parameter>
         <name>password</name>
         <value>database user password</value>
      </parameter>
   </ResourceParams>
</DefaultContext>