Method and system for enabling collaborative authoring of hierarchical documents with locking

A method in a computer system is disclosed for enabling authors to work on hierarchical documents. The method comprises retrieving a hierarchical document from a server computing device, modifying the retrieved hierarchical document, sending an indication of the modification to the server computing device, and when the modification cannot be applied on the server computing device, reverting the modified hierarchical document to a current form of the hierarchical document on the server computing device. A system is disclosed for receiving an indication to lock a node, the indication identifying an owner of the lock, receiving an indication of a request to mutate the node, determining whether the request is from a user other than the owner of the lock, and when the user is not the owner of the lock, denying the request.