1. A method for scalable processing of client messages in a fulfillment system, the method comprising: storing a set of action tasks in an action task table according to predefined types of client files, the action task table specifying links to the action tasks and a processing sequence; enqueueing a client message on a work scheduling queue, the client message containing a first set of meta-data and a second set of meta-data concerning a client file, the client file accessible on a backing store; dequeueing a client message according to a priority based upon the first set of meta-data information; selecting an action task from the action task table based on the second set of meta-data information and the processing sequence; and processing the dequeued client message according to the selected action task on an available process from a group of parallel processes, whereby the processing of the file stored in the backing store is separated from the message processing flow.