Embodiments of the present invention provide a protocol for ensuring data integrity of requests made by clients of a social network service. In particular, when a client gets a confirmation from an update request, the confirmation is accompanied by a token that provides information about the update. When the client next makes a read request it passes the token along with the read request. The node at the social network service receiving the request then waits until it makes sure that it has received any notifications that precede the state represented by the token before it processes the request and replies to the client. The token might be, among other things, a physical timestamp, a counter reflecting transactions committed on a database server, or a vector timestamp. In addition, the same technique can be used to ensure ordering between read requests.