Account Handler manages the state of a single Fuchsia account (and its personae) on a Fuchsia device. It also provides access to authentication tokens for the Service Provider accounts associated with the Fuchsia account.
Account Handler component instances are launched by Account Manager and implement the fuchsia.auth.account.internal.AccountHandlerControl FIDL interface so they may be controlled by Account Manager. Each Account Handler component instance is responsible for handling a single Fuchsia account and only accesses the persistent storage for that one account.
Account Handler also implements the fuchsia.auth.account.Account and fuchsia.auth.account.Persona FIDL interfaces. These interfaces are not discoverable; Account channels may only be obtained through Account Manager and Persona channels may only be obtained from an Account channel.
AccountHandler implements the fuchsia.auth.account.internal.AccountHandlerControl FIDL interface. The crate's main function creates a single instance of AccountHandler and uses it to handle all incoming requests.
The AccountHandlerControl interface allows for delayed initialization of the Account Handler; the first call received on the interface must be one of the initialization methods that bind the handler to a particular account (either an existing account or a freshly created account). After this point no further initialization calls are allowed.
When this initialization call is received AccountHandler creates a single instance of the Account struct and uses this to serve subsequent AccountHandlerControl.GetAccount calls.
Account implements the fuchsia.auth.account.Account FIDL interface and stores an instance of the Persona struct representing the default Persona.
Persona implements the fuchsia.auth.account.Persona FIDL interface.
The Account Handler is not yet fully complete. In particular the change listener interfaces and local authentication state are not finished.
Currently the AccountHandlerContext is passed explicitly from Account Manager to Account Handler in the initialization call. In the future this context will instead be supplied in Account Handler's namespace as it is launched.
Currently Account Handler (and the associated FIDL interface) only handles a single persona for each account. Eventually we will support the creation and management of multiple personae.