Abstract: A method of synchronization for use in a distributed data processing system comprising a legacy computer having means for storing a master version of data, an application server, and a thin client computer which stores a copy of the master version of data. Firstly, the thin client executes operations locally on the copy. The operations are sent in a list to the application server. The application server executes the operations on the master data, on behalf of the thin client. If the operations can be executed successfully on the master version, synchronization occurs in that the successful operations are applied to the master version.