  Asynchronous programming has appeared as a programming style that overcomes
undesired properties of concurrent programming. Typically in asynchronous
models of programming, methods are posted into a post list for latter
execution. The order of method executions is serial, but nondeterministic. This
paper presents a new and simple, yet powerful, model for asynchronous
programming. The proposed model consists of two components; a context-free
grammar and an operational semantics. The model is supported by the ability to
express important applications. An advantage of our model over related work is
that the model simplifies the way posted methods are assigned priorities.
Another advantage is that the operational semantics uses the simple concept of
singly linked list to simulate the prioritized process of methods posting and
execution. The simplicity and expressiveness make it relatively easy for
analysis algorithms to disclose the otherwise un-captured programming bugs in
asynchronous programs.
