An EventAdapter is both a WriteEventAdapter and a ReadEventAdapter. Facility to convert from and to specialised data models, as may be required by specialized persistence Journals.
Typical use cases include (but are not limited to):
adding metadata, a.k.a. "tagging" - by wrapping objects into tagged counterparts
manually converting to the Journals storage format, such as JSON, BSON or any specialised binary format
adapting incoming events in any way before persisting them by the journal
Some journal may require a specific type to be returned to them, for example if a primary key has to be associated with each event then a journal may require adapters to return com.example.myjournal.EventWithPrimaryKey(event, key).
The toJournal adaptation must be an 1-to-1 transformation. It is not allowed to drop incoming events during the toJournal adaptation.
Value parameters
event
the application-side domain event to be adapted to the journal model
Attributes
Returns
the adapted event object, possibly the same object if no adaptation was performed