AMPS is a middleware that provides a framework to write any software application as an event driven, asynchronous process . Unlike conventional thread based implementations, AMPS allows highly concurrent applications to run as a single thread of execution.
AMPS implementations require that the application be modelled as a FSM (Finite State Machine) that changes state based on ‘events’. ‘Event handlers’ are written for each state change. Once envisioned in this way, implementations provide multiple benefits.
Some of the benefits of this programming model are:

• All execution is lock free. No locks, no mutexes, no semaphores required ever.
• All event handlers are deterministic
• Natural support for Symmetric multi-processing, Asymmetric multi processing and multi-core systems.
• Applications are cloud ready
• No system overhead in context switching between threads or waiting for locks.
• Code is free of subtle bugs arising out of deep coupling effects in thread based applications.

Applications built on top of AMPS today boast a range of highly concurrent applications. Among many others is a SIP based soft switche that can take up to 20,000 concurrent calls on a single processor (you can’t get any more concurrent than this to prove that all concurrent code can theoretically run without locks)