In the persistence.xml JPA configuration file, you can have a line like:
<persistence-unit name="com.nz_war_1.0-SNAPSHOTPU" transaction-type="JTA">
or sometimes:
<persistence-unit name="com.nz_war_1.0-SNAPSHOTPU" transaction-type=”RESOURCE_LOCAL”>
My question is:
What is the difference between transaction-type="JTA"
and transaction-type=”RESOURCE_LOCAL”
?
I also noticed some persistence.xml files with the transaction-type missing. Is it correct?
"The transaction-type attribute is used to specify whether the entity managers provided by the entity manager factory for the persistence unit must be JTA entity managers or resource-local entity managers. The value of this element is JTA or RESOURCE_LOCAL.
The Java Persistence API allows you to define multiple persistence units, each of which can map to a separate database.
The persistence. xml configuration file is used to configure a given JPA Persistence Unit. The Persistence Unit defines all the metadata required to bootstrap an EntityManagerFactory , like entity mappings, data source, and transaction settings, as well as JPA provider configuration properties.
Default to JTA in a JavaEE environment and to RESOURCE_LOCAL in a JavaSE environment.
With <persistence-unit transaction-type="RESOURCE_LOCAL">
you are responsible for EntityManager
(PersistenceContext/Cache
) creating and tracking
EntityManagerFactory
to get an EntityManager
EntityManager
instance is a PersistenceContext/Cache
An EntityManagerFactory
can be injected via the @PersistenceUnit
annotation only (not @PersistenceContext
)@PersistenceContext
to refer to a unit of type RESOURCE_LOCAL
EntityTransaction
API to begin/commit around every call to your EntityManger
entityManagerFactory.createEntityManager()
twice results in two separate EntityManager
instances and therefor two separate PersistenceContexts/Caches
.EntityManager
in use (don't create a second one unless you've destroyed the first)With <persistence-unit transaction-type="JTA">
the container will do EntityManager
(PersistenceContext/Cache
) creating and tracking.
EntityManagerFactory
to get an EntityManager
EntityManager
supplied by the containerEntityManager
can be injected via the @PersistenceContext
annotation only (not @PersistenceUnit
)@PersistenceUnit
to refer to a unit of type JTAEntityManager
given by the container is a reference to the PersistenceContext/Cache
associated with a JTA Transaction.EntityManager
cannot be used because there is no PersistenceContext/Cache
.EntityManager
reference to the same unit in the same transaction will automatically have a reference to the same PersistenceContext/Cache
PersistenceContext/Cache
is flushed and cleared at JTA commit timeIf you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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