I need to extract a connection object from an entity manager

[mackmak]

Good Morning,
i am trying to do what this text says:

JPA 2.0
entityManager.getTransaction().begin();
java.sql.Connection connection = entityManager.unwrap(java.sql.Connection.class);
...
entityManager.getTransaction().commit();
JPA 1.0
entityManager.getTransaction().begin();
UnitOfWork unitOfWork = (UnitOfWork)((JpaEntityManager)entityManager.getDe legate()).getActiveSession();
unitOfWork.beginEarlyTransaction();
java.sql.Connection connection = unitOfWork.getAccessor().getConnection();
...
entityManager.getTransaction().commit();

Which is from this page:

EclipseLink/Examples/JPA/EMAPI - Eclipsepedia
But i can't understand what is that unitOfWork . Could somesone explain that?
I whould also like to know how to get the jpa version (though i believe mine is 1.0, once the unwrap method is not shown by eclipse).

Thanks in advance.