indirect jndi lookup of resource

How do I use an indirect jndi lookup of a datasource?  WAS 6 server
gives a warning that direct JNDI lookups are depreciated and I should be
using indirect lookups.  I tried the following code and still get the
warning.  Is there something I need to set up in the WAS server, like a
Connection Factory?  The code works, just gets the warning message in
the server logs.  The word 'indirect' tells me that I shouldn't be using
the datasource name in the application code, but I can't figure out the
correct code.
 
web-xml:
 
<resource-ref>
     <res-ref-name>jdbc/myds</res-ref-name>
     <res-type>javax.sql.DataSource</res-type>
     <res-auth>Application</res-auth>
     <res-sharing-scope>Shareable</res-sharing-scope>
  </resource-ref>
 
application code:
   InitialContext ctx = new InitialContext(); 
   ds = (DataSource)ctx.lookup("java:comp/env/jdbc/myds");