Undoing a function requested by a first client station on a computer object stored on a server station of a communication network is provided. The execution of the function is adapted to manipulate the object from an earlier state to a manipulated state. The undoing is performed by receiving a request to undo the execution of the function. The earlier state of the manipulated object is obtained. Then, a response is sent to the first client station via the communication network, the response comprising a sum of money less than or equal to an execution cost associated with the function.