Java EE (Java Enterprise Edition) General Discussion

Hi everybody.
i've some problem with realm in tomcat. if i use datasource every time i attempt to login the result is an error-login (i don't have the authentication), but if i use a direct connection at db all works fine.
when i try to use datasource, in tomcat log there's this exception:

27-lug-2007 18.37.51 org.apache.catalina.realm.DataSourceRealm open
GRAVE: Exception performing authentication
javax.naming.NameNotFoundException: Name jdbc is not bound in this Context
        at org.apache.naming.NamingContext.lookup(NamingContext.java:769)
        at org.apache.naming.NamingContext.lookup(NamingContext.java:152)
        at org.apache.catalina.realm.DataSourceRealm.open(DataSourceRealm.java:401)
        at org.apache.catalina.realm.DataSourceRealm.authenticate(DataSourceRealm.java:282)
        at org.apache.catalina.authenticator.FormAuthenticator.authenticate(FormAuthenticator.java:257)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:416)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
        at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
        at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
        at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
        at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
        at java.lang.Thread.run(Thread.java:595)

someone can help me to use realm whit datasource?

so:

i've this context.xml

if i use this, the authentication login doesn't work

<?xml version="1.0" encoding="UTF-8"?>
<Context path="/realm">
   <Resource auth="Container" 
   driverClassName="org.postgresql.Driver" 
   maxActive="20" 
   maxIdle="10" 
   maxWait="-1" 
   name="jdbc/postgres" 
   password="postgres" 
   type="javax.sql.DataSource" 
   url="jdbc:postgresql://localhost:5432/qo_db" 
   username="postgres"/>
  <Realm className="org.apache.catalina.realm.DataSourceRealm" 
  dataSourceName="jdbc/postgres" 
  debug="99" 
  roleNameCol="role_name"
  userCredCol="user_pass"
  userNameCol="user_name" 
  userRoleTable="user_roles" 
  userTable="users"/>
  
</Context>

if i use this all works, and i can use realm to login.

<?xml version="1.0" encoding="UTF-8"?>
<Context path="/realm">
    <Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
           driverName="org.postgresql.Driver"
           connectionURL="jdbc:postgresql://localhost:5432/qo_db"
           connectionName="postgres"
           connectionPassword="postgres"
           userTable="users" 
           userNameCol="user_name" 
           userCredCol="user_pass"
           userRoleTable="user_roles" 
           roleNameCol="role_name"/>

</Context>

my web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>user.jsp</welcome-file>
    </welcome-file-list>
    
    
    <security-constraint>
        <web-resource-collection>
            <web-resource-name>Public Area</web-resource-name>
            <!-- Define the context-relative URL(s) to be protected -->
            <url-pattern>/index.jsp</url-pattern>
            <url-pattern>/login.jsp</url-pattern>
        </web-resource-collection>
    </security-constraint>
    
    <security-constraint>
        <web-resource-collection>
            <web-resource-name>Protected Area</web-resource-name>
            <!-- Define the context-relative URL(s) to be protected -->
            <url-pattern>/user.jsp</url-pattern>
        </web-resource-collection>
        <auth-constraint>
            <!-- Anyone with one of the listed roles may access this area -->
            <role-name>User</role-name>
            <role-name>Admin</role-name>
        </auth-constraint>
    </security-constraint>
    <!--  uses form-based authentication -->
    <login-config>
        <auth-method>FORM</auth-method>
        <form-login-config>
            <form-login-page>/login.jsp</form-login-page>
            <form-error-page>/fail_login.html</form-error-page>
        </form-login-config>
    </login-config>
    <!-- Security roles referenced by this web application -->
    <security-role>
        <role-name>User</role-name>
    </security-role>
    <security-role>
        <role-name>Admin</role-name>
    </security-role>
    
    
    <resource-ref>
        <description>DB Connection</description>
        <res-ref-name>jdbc/postgres</res-ref-name>
        <res-type>javax.sql.DataSource</res-type>
        <res-auth>Container</res-auth>
   </resource-ref>
</web-app>

the db and jsp are ok.