In today's world of Internet scale applications and cloud computing, the choice of the programming model has a major impact on several aspects of a large and complex software artefact. Some of the key aspects include software development time, performance, reliability, scalability, flexibility, robustness and portability to name a few. The most commonly used programming model for highly concurrent, high performance server class applications is the conventional multi-threaded model. This model is well known to most programmers and is considered well understood in the developer community at large. However, there are some fundamental issues with this model that make it unsuitable for parallel systems that may need to scale to Internet and the cloud.
AMPS presents an asynchronous, event-driven programming model to the application developers.
AMPS programming is slightly different.

• Application is modelled as a FSM (Finite State Machine).
• Event handlers are written for each state transition. Each event handler is an atomic unit of execution and always deterministic.
• FSM moves from state to state based on the stimuli provided to it by the event handlers.
• Event handlers terminate on each blocking operation so that the next event can be processed.
• An event handler will never wait for any operation to complete because at one time only one event handler is being processed by one core.
• Events happen asynchronously and the program does not wait or block ever for any event to complete.
• Once terminated, events are en-queued until the notification system notifies that the blocking operation has completed.
• There is a single main thread of control called controller in the program that usually waits in an infinite loop for any events to occur.
• Event handlers register their interest in other event handlers’ outputs.
• All communication among event handlers is done through message passing