The access intent service enables developers to precisely tune the management of application persistence.
Access intent enables developers to configure applications
so that the EJB container and its agents can make performance optimizations
for entity bean access. Entity beans and entity bean methods are configured
with access intent policies. A policy is acted upon by either the combination
of the WebSphere EJB container and Persistence Manager (for container-managed
persistence (CMP) entities) or by bean-managed persistence (BMP) entities
directly. Note that access intent policies apply to entity beans only.
Predefined access intent policies
Seven predefined access intent policies are available. The policies are composed of different attributes. You can directly configure most of these attributes only with WebSphere Business Integration Server. The access type is of primary interest and controls the isolation level, lock type, and duration of locks obtained when bean data is read from the database.
A pessimistic access type indicates to hold locks for the duration of the transaction under which the data loads. An optimistic type indicates to drop locks immediately after the data is read from the backend. A read type indicates that the run time must not allow updates to the data; any attempt to do so on data read under a read type results in an exception. Update types permit you to change data. The seven policies and their attribute definitions follow:
Note that to support connection sharing, you must ensure that all data loaded in the same transaction is under the same isolation level. Verify that all participating methods that drive loads are configured with either a pessimistic access type or an optimistic access type.