By default the JPAWriter joins an existing global transaction. The user should package a persistence.xml that sets the transaction-type attribute to JTA and declare a jta-data-source

Optionally the JPAWriter can be configured to begin and commit transactions in synch with the global transactions for use with non-jta-data-sources and connection URLs. In this case the persistence.xml should set the transaction-type to RESOURCE_LOCAL and declare a non-jta-data-source or connection URLs