[vos-d] s5 concurrency (design part 2)

[Reed Hedges]

> So, a key goal in the s5 design process is to introduce a computational 
> model.  Having thought it through and done some research, I determined 
> that the Actor Model (http://en.wikipedia.org/wiki/Actor_model) is the 
> closest to what we're trying to do, and so serves as a basis going 
> forward as we turn it into a concrete design.
> 
> The key features of the actor model are:
>  - Each actor executes independently of other actors
>  - Actors can send asynchronous messages to other actors
>  - Actors can execute behavior based on received messages
>  - Actors can create other actors
>  - Actors have no shared state


There's also something called Flow-Based Programming that is similar. In
some ways it's closer to VOS since Actors are, I think, more like method
handlers (in VOS terminology). 

But "Actors Model" is more well known and more carefully studied and
defined (though I guess we will be deviating from it)

Reed