As far as I understand there are two types of DataSource connections, javax.sql.DataSource and javax.sql.XADataSource, this tutorial explains that javax.sql.DataSource give the connection the ability to be pooled and javax.sql.XADataSource give the connection distributed transactional behavior.
I understand most XADataSource will implement connection pooling as well as distributed transactions so I don't see the point to use a DataSource when you could use a XADataSource and have both.
Are there any tradeoff when choosing a XADataSource over a DataSource?
I understand is not mandatory for a XADataSource to use pooled connections, is it there a way to find out if a XADataSource uses pooled connections or only relying on the XADataSource provider's documentation?
EDIT:
I am refering to javax.sql.DataSource and javax.sql.XADataSource because those are the types Tomcat 8 factory gives you:
Type should always be javax.sql.DataSource or javax.sql.XADataSource
Depending on the type a org.apache.tomcat.jdbc.pool.DataSource or a org.apache.tomcat.jdbc.pool.XADataSource will be created.
I do understand that in the end I would be using a DataSource on my code as an API, abstracting the underlying implementation... my question is more related on the decision making process I have to go through when I am configuring Tomcat 8 (or any other server as well).
I want to have pooled connections and there are many XADataSource implementations that will give transactional and pooled connections, so why not always use XADataSource if I will get more? (this of course doesn't applies for a XADataSource that doesn't implements pooled connections)