Re: About component architectures...

On Fri, 26 Apr 2002, Christian Schlegel wrote:

[...]
> > Resource scheduling
> > Alloting resources to components, allowing them to progress in
> > parallel, and making sure they don't use the resources in conflicting
> > modes.
> 
> Resource scheduling is a key feature at various levels. Therefore there
> will be no unique place for resource scheduling but many different
> instantiations. 
[...]
> Therefore I
> don't see resource scheduling as a generic responsibility within every
> component, only in the sense that a component should at least accept
> resource requests / resource constraints and scheduling requests (like
> deactiating a module) from outside.

That's the same thing. You're not very consistent IMHO: on the one
hand you say resource scheduling is ubiquitous, and on the other hand
you say that is not a generic responsibility in every component...
All the examples you give corroborate my statement that resource
scheduling _is_ needed in every component :-) (Of course, it's
concrete functionality will be different.)


> 
> >
> > Sequencer
> > The sub-component within a component that is responsible for the
> > synchronized execution of a service by other sub-components within
> > that component. Possible mechanisms for sequencing are: finite state
> > machines, Petri nets, task nets, declarative programs, etc.
> 
> The sequencing  in the sense of three-layer architectures (like 3T etc)
> often is called "sequencing layer". 
[...]
> Therefore
> "sequencing layer" should be "sequencing component" in our terminology.

I am not talking about layers: that the system architecture. I'm
talking about the internal component architecture; and every component
internally has a need for a sequencing functionality. That's what I
call a sub-component.

> To be consistent one should call your "sequencer" something like
> "component sequencer" 
No. It doesn't sequence the execution of components, but of their
actions.

Herman

-- 
K.U.Leuven, Mechanical Engineering, Robotics Research Group
<http://www.mech.kuleuven.ac.be/~bruyninc>  +32 16 322480