DeflateAuthDB serializes AuthDB to byte buffer and compresses it with zlib.

InflateAuthDB is reverse of DeflateAuthDB.

AuthService represents API exposed by auth_service.

Notification represents a notification about AuthDB change.

Snapshot contains AuthDB proto message (all user groups and other information received from auth_service), along with its revision number, timestamp of when it was created, and URL of a service it was fetched from.