Server and a method for implementing a state tracking mechanism in a communications session between the client system

摘要

A method of implementing a state tracking mechanism in a communications session between a server (1) and a client system (2), wherein, in the course of the communications session, application data is provided to the client system (2) in accessible form only if the client system (2) has a valid value of state tracking information, includes transmitting a message carrying a new value of the state tracking information to the client system (2). It further includes calculating the value of the state tracking information valid after transmission of the message using as input at least the new value carried in the message and a datum maintained at the client system (2).