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2/4/2002 8:48:21 PM, "Jeff Greif" <firstname.lastname@example.org> wrote:
>I believe the author of the 'rant' mentioned below has a poor understanding
>of the CORBA paradigms and out-of-date knowledge of what CORBA supports of
>the various communications possibilities.
I wouldn't quarrel with that ... the point I saw in it was the bit about
"messages ... have a pretty general meaning, and it's up to the program to
interpret what they mean for it."
I just read an interview with Clay Shirky (Warning! Complexity Ahead) at
which seems to make the point more effectively:
"Designers of successful applications are going to rely more on protocols and
less on APIs [application programming interfaces], in part because protocols
are simpler and change less, and in part because they are defined
independently of the software. One of the huge surprises of Internet scale is
that well-defined protocols, which are almost brain-dead in their simplicity,
have superior survival characteristics to beautifully designed and crafted
APIs that change once a year."
I'm taking "protocols" to mean "simple,loosely coupled, possibly asynchronous
message exchange patterns" and "APIS" to mean "tightly coupled, RPC message
exchange patterns" ... hope I'm not imposing too many of my own biases :~)
Anyway (and drifting slightly off-topic) I was struck by the similarity of
what Shirky was saying and the message of Steven Jones' EMERGENCE book,
which describes hallmarks of self-organizing systems as being built out of
feedback directed, locally oriented, pattern recognizers.
"It is now physically impossible to operate with an accurate picture of
global state. Any local node cannot operate with a picture of what's going on
in all other parts of the system. Typically, enterprise software has tried to
keep track of everything going on in the system.
... Biological systems operate within a local context. Your kidneys only know
what's going on in the kidneys, yet the whole organism functions. The kidneys
say, "Here comes some poison, and I'm going to get rid of it." They don't
know how the poison got there. They weren't talking to the mouth or the
stomach; it just came in for processing....
Biological systems have a property called homeostasis, which is the ability
to return to some kind of internal norm.
And that ability to return to some kind of norm despite all kinds of external
forces is going to be critical for any kind of system exposed to the
Internet.. To most people, Napster meant kids stealing music. But to
application designers, what it did was build a five 9s [99.999% uptime]
service on fantastically unreliable hardware."