The 'public' schema holds all windmill domain specific tables. The 'sns' schema holds all Amazon SNS specific tables. The 'apple' schema holds all Apple specific tables.
The relationship is one-directional as in 'sns' -> 'public' 'apple' -> 'public' This allows the 'public' data to exist independently of the 'sns', 'apple' ones.
The 'secret' schema holds potentially data that is considered cryptographically secret.