Mechanisms are provided for identity mapping in synchronization systems.
For example, entities can be mapped across various entity stores, such
that an entity in one store can be identified with an entity in another
store even if such entities are of different types. When entities are
being synchronized across various entity stores, new or updated entity
identities (and associated metadata) can be supplied to these stores as
part of the same operation as that used for supplying changes during
synchronization: entities can be merged and associated identity
information and metadata can be changed accordingly; entities can be
resurrected and new identity information can be created; metadata can be
utilized even though entities are deleted, and so on.