Firebase Sharing Schema (V2).js

{
  root: {
    "objects" : {
      "$object_id" : {
        "permissions" : {
          "isPublic" : BOOL,
          "users" : {
            "$user_id" : BOOL
          }
        },
        ...
        // data goes here
      }
    },
    "permissions" : {
      "public" : {
        "$object_id" : BOOL
      },
      "user" : {
        "$user_id" : {
          "$object_id" : BOOL
        }
      }
    }
  }
}