The wrapper project
Thu Aug 21 16:43:42 CEST 2003
On Thu, 21 Aug 2003 11:06:54 +0200 (CEST)
Joe Armstrong <> wrote:
> I'm back .... (been on holiday)
> I've been thinking about stuff.
> Once upon a time I was interested in "how to program" I think that
> we now know how to do this (not perfectly, but adequately) - now I'm
> interested in "fitting things togther".
> I have convinced myself of the following:
> 1) Systems must be made of *isolated* components.
> 2) The components must communicate by asynchronous message
> passing... (and a few more things which are not relevant to this
> Isolation is the *essential* characteristic. It means that if one
> component crashes, the other components must not themselves crash.
See also: protected memory.
> processes running on the same machine should be as isolated as if one
> ran in (say) Sweden and the other in (say) the USA.
> What these process are written in (language) and what they run on
> (OS) is *irrelevant* - But the *protocol* between them is vital (hence
> my thoughts on UBF and the like (see www.sics.se/~joe/ubf).
Then the protocol becomes the OS, for all intents and purposes.
(And... you don't *really* believe that the choice of language is
"irrelevant", do you? :)
On Thu, 21 Aug 2003 17:04:03 +0200
Joachim Durchholz <> wrote:
> To keep the number of potential interactions down, Parnas propagated
> "information hiding", cutting down on the number of interactions that
> a compiler will allow. (Information hiding is not intended to prevent
> programmers from looking into components, its for preventing
> components from looking into other components.)
See also: the Law of Demeter.
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