[ogsa-wg] Glossary terms for Thursday's call

[Donal K. Fellows]

Strong, Paul wrote:
> Within the RM-WG we have split attributes into configuration attributes 
> and state attributes.  Configuration attributes to some degree define 
> behavior, defining or constraining the set of allowed states, as well as 
> the possible values of state attributes and allowed transitions between 
> states.  Clearly configuration attributes are “interesting”, and thus 
> according to the definition below they would be considered part of the 
> state.  I’m not sure that this is the case.

An argument that I made during the call (and which it might have been
nice to have delved into in more detail if we'd had a few days instead
of 15 minutes!) is that an altered configuration creates a different
resource/stateful entity[*], but an altered state is something that is
expected during the normal working lifetime of a resource and does not
change the fundamental nature of that resource. That is, a change of
config is qualitatively different to a change of state, even if both are
(represented as) attributes.

In general, there are loads of definitions of state (I've got a
background which leads me to regard it as really a partial function
whose domain is the cartesian product of time and names for "stateful"
things) but they're just different ways of looking at the same thing.
The good aspects of the current definition are that it is observable and
changes in it are events, things which are not implicit in the standard
CS definitions of the term and yet are very useful for grids.

Donal.
[* As you can tell, I've lost track of what kind of thing contains such
    attributes. I know *I* think of them as resources, but that doesn't
    make me right. :-) ]