A method comprising creating and publishing (H, K) an application program interface (API) enabling access to a dataset from a source data file; determining, by an application, a type of change (E) that has occurred to the source data file; and in dependence at least on a result of said determining, taking at least one action (H, K) relating to permitting subscriber access to the dataset of the changed source data file. The action may comprise permitting subscriber access to the dataset from the changed source data file either: in place of the dataset from the source data file (H), using the API; or by creating and publishing a new API (K). The permitting access to the dataset may also depend on subscriber access controls and/or publication controls under the control of a publishing entity. Changes to datasets may be provided to the application by a file synchronization system.