Operational Attributes

Identity Manager predefines several attributes that are required for the repository to work correctly. ID, type, and name are especially important.

Every PersistentObject stored in the repository has a globally unique internal identifier (ID). An ID value is unique across time and space, and a generated ID value is never re-used. (Some predefined Identity Manager objects have well known identifiers that are defined as program constants. These are known as fake IDs.) The repository ensures that an object’s ID will never change.

Objects of the same type typically map to the same Java class. That is, they are constructed as instances of the same Java class when deserialized. Where there is not a one-to-one correspondence between type and Java class, every object of the same type at least uses the same mechanism to look up the corresponding Java class. (For example, some types of objects expose a class attribute that contains the fully qualified class name.)

An object’s name must be unique within type. That is, only one object of a type can have a particular name. (However, another object of a different type can have the same name.) Thus, each type effectively defines a subordinate namespace. You can change an object’s name, but you cannot change an object’s ID.