How to use Connection Tag in JDBC

[Niu, Jean (J.)]

>From document, there are three ways to use Connection tag:
1. JNDI named JDBC DataSource
2. Use a DataSource object
3. Use a database URL

I know how to use database URL, but don't know how to use DataSource object
and JNDI. Could somebody give me a working example how to setup DataSource
object and JNDI so the Connection tag can refer to these object.

Thanks.

Jean