The first and most basic characteri

The first and most basic characteristic of entities is that they are persistable. This generally just means
that they can be made persistent. More specifically, it means that their state can be represented in a
data store and can be accessed at a later time, perhaps well after the end of the process that created it.
We could call them persistent objects, and many people do, but it is not technically cor r ect. Str ictly
speaking, a persistent object becomes persistent the moment it is instantiated in memory. If a
persistent object exists, then by definition it is already persistent.
An entity is persistable because it canbe created in a persistent store. The difference is that it is
not automatically persisted, and that in order for it to have a durable representation the application
must actively invoke an API method to initiate the process. This is an important distinction because it
leaves control over persistence firmly in the hands of the application. The application has the
flexibility to manipulate data and perform business logic on the entity, making it persistent only when
the application decides it is the right time. The lesson is that entities may be manipulated without
necessarily being persisted, and it is the application that decides whether they are or not.
Identity