Default transactionManager for WebSphere application not using EJBs

[Michael Schall]

We are using iBATIS in a large application that does not use EJBs and it
works great.  We are seeing some issues where we are using more connections
than we think we should be.  We are wondering if we have some issues with
connections/transactions not closing as fast as we would like them to.  Our
current transactionManager looks like the following:

    <transactionManager type="JDBC" commitRequired="true">
        <dataSource type="JNDI">
            <property name="DataSource" value="java:comp/env/jdbc/..."/>
        </dataSource>
    </transactionManager>

A link (
http://opensource.atlassian.com/confluence/oss/display/IBATIS/Environment+Specific+Information)
in a recent post pointed me to a different config:

    <transactionManager type="JTA" commitRequired="true">
        <property name="UserTransaction"
value="java:comp/env/UserTransaction"/>
        <dataSource type="JNDI">
            <property name="DataSource" value="java:comp/env/..."/>
        </dataSource>
    </transactionManager>

>From what I have read, JTA is needed if you require 2 phase commits, which
we don't.  Is JTA a better choice anyway?  What is the UserTransaction
property doing here?

Thanks for your time.

Mike