OpenOrCreateDatabase opens a sqlite3 database for reading or writing, and returns a *FERRYUIDDatabase object.

ApplicationId is used to uniquely identify a sqlite database as belonging to an application, rather than being a simple DB.

ManagedTokensDatabase is a database in which FERRY username to uid mappings are stored.

FerryUIDDatum represents a piece of data from FERRY that encompasses username to UID mapping.

PushErrorCount is an interface that wraps the Service, Node, and Count methods.

SetupErrorCount is an interface that wraps the Service and Count methods.