Definition of ``codel'' + ``execution engine'' ...

I'm reworking the website, to bring it somewhat in sync with the
evolution of the last months. One of the important concepts that need
clarification for newcomers (and not-so-newcomers :-) is the
``codel''. I'll try a definition, but please correct and complement
it.

Another topic is the ``execution engine''. (Or should I call it otherwise?)

Do I have to put other definitions on-line? If so, please send me
inputs. (Via the mailing list!)


Herman
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Codel: any part of a component that must be executed atomically,
within the context of this component. In this sense, it is the basic
building block of an Execution engine.
It is important to stress that the atomicity must hold only within the
component only; the operating system can preempt the codel by
scheduling of other components. (Unless the codel takes explicit
actions to make pre-emption impossible.)

Execution engine (also known as: task execution control, task
sequencing):  the infrastructure software that takes care of the
proper execution of a given task, within the context of some
state-based task sequence (Finite State Automaton; Petri Net;
Hierarchical State Machine; StateCharts; ...). Each state has a codel
that contains the basic functional part of the task in that state, and
some auxiliary functions, that implement what must be done at state
entry and state exit.
The execution engine helps, for example, to implement controllers that
have to switch their control algorithms on-line (e.g., in the control
of a walking device).