Looking at the code, this is what I understand:
- Flash data is ultimately designed to store data between requests.
- Since Play has no state, this state is stored in the session cookie, which is sent to the client and sent back from the next request.
- A data card is data that is received from a client through a cookie.
- Out out Map is the data that the Play application writes to the Flash instance.
- If the data has changed, the data in Out Map is used to create the contents of the cookie to be sent back to the client.
, , , flash.discard() , , flash.clear() , ...