P

Persist

To store the current state of an object in a datastore. The object can then be reconstructed by retrieving its state from the datastore. Some of the object's state may be persistent and some may not.

Persistence-aware class

Any class that is not an application data class but that accesses the managed field of an application data class. In essence, it is a class that is friendly with a managed field of an application data class.

Persistence by reachability

The automatic insertion of transient objects into the datastore if they are referred to by the persistent fields of existing or newly made persistent objects.

Persistence-capable class

Either an application data class that has been enhanced and therefore implements the PersistenceCapable interface, or a system class that JDO supports directly.

PersistenceCapableclass

A synonym for application data class.

Persistent field

A member field of the application data object whose value JDO manages both transactionally and persistently. The value of the object's field is stored in the database and fetched from the database as needed.

Persistent object

A data object that JDO is managing persistently. As a result, its persistent state is stored in the datastore.

Persistent object model

The classes of objects and the relationships of objects that hold persistent state. Since the focus in this book is on the data objects, the term object model is often used as shorthand for the persistent object model. Strictly speaking, the object model includes all of the objects in the application, not just the data objects.

See also Persistent object model.

Persistent services

The functions to Create, Retrieve, Update, and Delete information in the datastore. These services are sometimes called CRUD.

Persistent state of an object

The values of the object's persistent fields.