Doubts concerning External Connection Pool

Question

A few questions:
1. How can I set up an external connection pool with toplink? or in another words, assuming that I have successfully configured a connection pool (and a datasource) on my weblogic app-server, how do I configure Toplink to use the same?
2. I am trying to achieve the above (refer point 1), by defining my custom connector (by extending TOPLink.Public.Sessions.DefaultConnector). The custom connector provides connections using the dataSource.getConnection(). Now, the question is
- Where will the pooling happen in this case? i.e. Will Toplink use its own connection pool (populate its own connection pool with container managed data source), and issue connections (container managed) from there or will it make use of the container managed pooling (and ask for connections from the container managed pool, as and when required)? The subtle difference being, weblogic will not be able to validate a connection before issue in the former case.
3. This question is similar to point 2, but talks in terms of a practical example. Assuming that if I am using the custom connector successfully in my code, then if I pull out the network cord and reconnect again, I expect the container to provide me with a valid connection (as weblogic can be configured to perform a validity check on a connection before issuing). I am getting a 'connection reset by peer' error in my application (indicating that either the container fails to provide a valid connection, or toplink does not use the container managed pool effectively). I guess, Toplink still uses its own pool but this time it is pooling container managed dataSources. Since the connections are issued from Toplink and not container, here is no validation/reconnection happening for the connection, before issue. Please comment if I am thinking in the right direction or not. If not, how you can explain the above failure?
4. My aim is to utilise the container's connection pool, and Toplink's ability to perform the rest of the things (including transactions). Is that possible?

Answer 1

Vikas,
TopLink can easily be configured to use the external connection pool of an server. This can be accomplished with API but more commonly using the sessions.xml configuration file for the SessionManager. In the product we ship examples for WLS that make use of data sources configured in the server. The portion of the sessions.XML file in question is:
          <login>
               <user-name>weblogic</user-name>
               <password>weblogic</password>
               <datasource>java:comp/env/jdbc/ejbJTSDataSource</datasource>
               <non-jts-datasource>java:comp/env/jdbc/ejbNonJTSDataSource</non-jts-datasource>
               <uses-external-transaction-controller>true</uses-external-transaction-controller>
               <uses-external-connection-pool>true</uses-external-connection-pool>
          </login>
          <external-transaction-controller-class>oracle.toplink.jts.wls.WebLogicJTSExternalTransactionController</external-transaction-controller-class>
This sets TopLink up with both data source access to the JTA and non-JTA connection pools. The full example also includes a domain where the data source is configured.
When TopLink is using the connection pool of the server (external connection pooling) it will not pool its own connections. TopLink will request a connection from the pool each time one is required and release it back when done. This leaves the server responsible for the number of connections available and also for supporting database re-connection.
Doug