The present invention is a method embodied in a deferred-synchronous messaging software for providing deferred-synchronous messaging capability for applications in a non-threading model. In essence, it enables asynchronous behavior to be executed in parallel within a single-threaded environment, without need of either an operating system or programming environment supporting threads in order to perform multiple synchronous calls in different processes. As a result, applications are able to perform simultaneous multiple synchronous calls without spawning multiple processes. The present invention provides a model to allow applications to enhance their business processes without using inter-process communications. Thus, it allows simultaneous multiple business synchronous processing without complex inter-process communication logic.