1. At a computer system including at least one processor and a memory, in a computer networking environment including a plurality of computing systems, a computer-implemented method for providing schedule-based processing using web service on-demand message handling threads, the method comprising: an act of receiving at a web service platform a message from a client that is specified for schedule-based, background handling, wherein the web service platform includes an on-demand message handling service with one or more threads that are configured to perform on-demand message processing; an act of the web service platform loading the on-demand message handling service including the on-demand message handling threads; and an act of implementing the on-demand message handling service's threads to perform background processing on the received client message, wherein client messages specified for background handling are handled as service-initiated on-demand tasks.