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Re: Clarifying exchange type

From: Kohei Honda <kohei@dcs.qmul.ac.uk>
Date: Mon, 30 Oct 2006 09:22:14 +0000
Message-ID: <4545C446.2090109@dcs.qmul.ac.uk>
To: Gary Brown <gary@pi4tech.com>
CC: "Monica J. Martin" <Monica.Martin@Sun.COM>, Martin Chapman <martin.chapman@oracle.com>, 'WS-Choreography List' <public-ws-chor@w3.org>

A note on co-relation identity and session:

I wrote about corelations: I would like to note its historical context. 
As fart as
I know, this idea was first presented in scientific texts in definite 
forms in two
ways:

(1) Nonces (challenge strings) in Needham-Shroeder protocol.
(2) Private name passing in the pi-calculus.

Further going back in the history, similar ideas can be found in actor 
models,
TCP's ack, and the use of document identities in financial processing.

Making interactions collected into one by this device into types for 
conversation
(in the way we know of as session types now) were done by many people
including myself since 1994. As noted, these are called session types.

I do not know from where this term "corelation" comes from.  I think it 
is also
a possible name. Personally I myself think "session identities" (and 
associated
"session instances") may denote its meaning more clearly.

Session is a fundamental idea in all high-level (and low-level) 
communications
among computing agents (just consider your session with any web service for
human, filling fields etc.).  It emphasises more in what context 
conversations
are going on rather than individually relating this message and others. 
So the
latter (co-relation) does have a place different from session. My 
preference is
to use the corelation for more application-oriented situations, such as 
invoice
numbers.

After understanding the concepts clearly, a good terminology will naturally
arise.

kohei
Received on Monday, 30 October 2006 09:22:48 GMT

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