A Formal Specification of the Hormone Loop of an Artificial Hormone System

The Artificial Hormone System (AHS) is a completely decentralized operation principle for a middleware which can be used to allocate tasks in a system of heterogeneous processing elements (PEs) or cores. Tasks are scheduled according to their suitability for the heterogeneous PEs, the current PE load and task relationships. The AHS also provides properties like self-configuration, self-optimization and self-healing in the context of task allocation. In addition, it is able to guarantee real-time bounds for such self-X-properties. 

The operation principle of the AHS is based on the hormone loop. This is a sequence of actions and wait states executed periodically on each PE. We present a formal specification of the hormone loop in this paper. The outcome is to guarantee consistent hormone computation (important for holding the real-time bounds of the self-X properties) and a fast recognition of task or PE failures. Even more, we present an algorithm to terminate single PEs consistently.