A method is provided to synchronize a local data storage on a wireless computing device with a remote data storage located on a server based upon user defined business logic stored on the server and corresponding to a particular data object. The method employs a synchronization message that includes a data object to be updated, a corresponding action that has been performed on the data object and an old data object corresponding to the data object prior to when the action was performed. The user can define, by means of the business logic, validation, processing and conflict resolution functionality specific to a particular type of data object. The method includes provisions for both on-line and off-line synchronization.