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Re: Compendium of "synchronous" definitions

From: David Booth <dbooth@w3.org>
Date: Mon, 03 Mar 2003 13:23:49 -0500
Message-Id: <5.1.0.14.2.20030303131441.02e2c448@localhost>
To: www-ws-arch@w3.org
Cc: Francis McCabe <fgm@fla.fujitsu.com>

Frank,

Sure, sorry I missed it before.  Let's name yours "frank-1":

Definition frank-1
http://lists.w3.org/Archives/Public/www-ws-arch/2003Mar/0023.html
[From from Communicating Sequential Processes]
Synchronous
A rendezvous of two activities is synchronous if they complete
simultaneously.


>Date: Mon, 3 Mar 2003 09:10:24 -0800
>Cc: www-ws-arch@w3.org
>To: "David Booth" <dbooth@w3.org>
>From: Francis McCabe <fgm@fla.fujitsu.com>
>Message-Id: <05F781DC-4D9B-11D7-B6EA-000393A3327C@fla.fujitsu.com>
>Subject: Re: Compendium of "synchronous" definitions
>
>
>David:
>    I would appreciate it if you could add mine to the long list:
>
>a straightforward definition of synchronous:
>
>A rendezvous of two activities is synchronous if they complete
>simultaneously.
>
>The language, if not the definition, comes from Communicating
>Sequential Processes.
>
>One might try to sharpen this up by defining simultaneously in terms of
>clocks etc. But that is not necessary; because an alternative view of
>this definition is:
>
>An activity involved in a synchronous rendezvous may assume that the
>rendezvous is complete for both sides if it 's side completes.
>
>Frank
>
>
>On Thursday, February 27, 2003, at 04:58  PM, David Booth wrote:
>
> >
> > Here are the proposed definitions of "synchronous" that I've collected
> > from the list.  If I've missed any, it was only due to volume of
> > messages I was trying to sort through -- not due to any desire to
> > slight anyone -- so please accept my apology.  If that happened, and
> > you do feel that (yet) another definition should be considered, please
> > re-submit it to the list by reply message and give it a unique name as
> > I've done with the others below, so that we can be clear when in
> > referring to them.
> >
> >          ==============================================
> >
> > Definition dbooth-2
> > [This is my attempt at combining the main concepts I've seen in
> > others.]
> > Synchronous interaction
> > An interaction is synchronous if the parties are involved in the
> > interaction at the same time and the interaction carries an
> > expectation of immediate processing.  A one-way interaction is
> > synchronous if successful message delivery implies that the message
> > either has been processed by the receiver or is actively being
> > processed.  A round-trip or more complex interaction is synchronous if
> > the initiator pauses some of its processing to wait for the
> > interaction's constituent messages to be processed.  In a round-trip
> > interaction, the request and response are often sent over the same
> > communication channel.
> >
> > ----
> > Definition dbooth-1
> > http://lists.w3.org/Archives/Public/www-ws-arch/2003Feb/0222.html
> > Property of an interaction whose results are directly following the
> > interaction. An interaction between an initiator and a respondent is
> > synchronous if the initiator blocks some further processing while it
> > waits for a corresponding action, response or acknowledgement from the
> > respondent.
> >
> > ----
> > Definition ugo-2c
> > http://lists.w3.org/Archives/Public/www-ws-arch/2003Feb/0386.html
> > Asynchronous: A request/response interaction is said to be
> > asynchronous when the request and response are chronologically
> > decoupled. In other words, the client agent does not have to "wait"
> > for the response once it issues the initial request. The exact meaning
> > of "not having to wait" depends on the characteristics of the client
> > agent (including the transfer protocol it uses). Examples include
> > receiving the response on a different thread, on a different socket,
> > on a different end-point, by polling the server, etc.
> >
> > Synchronous: The opposite of asynchronous.
> >
> > ----
> > Definition daveo-1
> > http://lists.w3.org/Archives/Public/www-ws-arch/2003Feb/0432.html
> > synchronous
> > a programmatic flow of control on the sender effectively does nothing
> > but wait for a response after sending it's request
> >
> > ----
> > Definition daveo-2
> > http://lists.w3.org/Archives/Public/www-ws-arch/2003Feb/0432.html
> > synchronous
> > the request and response flow forwards and backwards over the same
> > virtual connection between the sender and receiver.
> >
> > ----
> > Definition moberg-1
> > http://lists.w3.org/Archives/Public/www-ws-arch/2003Feb/0343.html
> > A web service response is said to be synchronous iff it is returned
> > using the same network connection used in sending the request to which
> > it is a response. (This implies that only one URL would be needed for
> > request-response MEP when the response is synchronous and uses a
> > transfer protocol that has URLs. It also implies that the request and
> > response occur within the interval of time that the network connection
> > exists. Also, there is overhead in setting up only one TCP connection
> > when TCP is used, and since we are talking about IP _connections_ that
> > will be almost always the case.)
> >
> > A web service response is said to asynchronous iff it is returned
> > using a network connection that is distinct from that used for sending
> > the request to which it is a response. (Implications: Two URLs are
> > needed to configure a request-response MEP when the response is
> > ==>asynchronous. The response connection may occur while the request
> > connection is still open or after it is closed. For TCP-based transfer
> > protocols, two connection setups will be needed.)
> >
> > ----
> > Definition assaf-3
> > http://lists.w3.org/Archives/Public/www-ws-arch/2003Feb/0354.html
> > A transport is synchronous iff the request is returned using the same
> > network connection.
> >
> > ----
> > Definition cutler-1
> > http://lists.w3.org/Archives/Public/www-ws-arch/2003Feb/0358.html
> > Synchronous: a request/response exchange that is correlated by virtue
> > of a serialized, sequenced exchange of messages between requestor and
> > respondant, typically over the same socket or stream.
> >
> > Asynchronous: a request/response exchange that is not synchronous,
> > typically relying on some mechanism such as Message-ID within the
> > messages to correlate the request and response messages.
> >
> > ----
> > Definition ferris-1
> > http://lists.w3.org/Archives/Public/www-ws-arch/2003Feb/0437.html
> > synchronous message exchange (applies to oneway as well as
> > request/response) requires that both sender and receiver, or initiator
> > and respondant, processes are running/active at the same time as the
> > exchange takes place. In the case of request/response, the exchange is
> > synchronous if both sender and receiver remain in the running/active
> > state for both the request and response.
> >
> > asynchronous message exchange (also applies to oneway or request
> > response) does not require, but does not preclude, that both sender
> > and receiver, or initiator and respondant, processes are
> > running/active at the same time as the exchange takes place. It
> > typcally requires some form of mediation between the sender and
> > receiver such as a message queue.
> >
> > ----
> > Definition mikec-1
> > http://lists.w3.org/Archives/Public/www-ws-arch/2003Feb/0318.html
> > (Taken from
> > http://whatis.techtarget.com/definition/0,,sid9_gci213080,00.html ?)
> > In program-to-program communication, synchronous communication
> > requires that each end of an exchange of communication respond in turn
> > without initiating a new communication. A typical activity that might
> > use a synchronous protocol would be a transmission of files from one
> > point to another. As each transmission is received, a response is
> > returned indicating success or the need to resend. Each successive
> > transmission of data requires a response to the previous transmission
> > before a new one can be initiated. Synchronous program communication
> > is contrasted with asynchronous program communication.
> >
> > ----
> > Definition walden-1
> > http://lists.w3.org/Archives/Public/www-ws-arch/2003Feb/0326.html
> > Synchronous, then, places a constraint on a response such that the
> > response must be received within a strictly or loosely defined time
> > quantum (strict vs lax synchrony), or else the exchange fails.
> > Asynchronous differs in that no amount of elapsed time signals the
> > failure of the exchange.
> >
> > ----
> > Definition assaf-1
> > http://lists.w3.org/Archives/Public/www-ws-arch/2003Feb/0321.html
> > An operation is synchronous if both service requester and service
> > provider
> > engage will always engage in that operation at the same time.
> >
> > ----
> > Definition assaf-2
> > http://lists.w3.org/Archives/Public/www-ws-arch/2003Feb/0321.html
> > An interaction is synchronous if activities demarcated by that
> > interaction
> > will always be performed at the same time.
> >
> >
> >
> >
> > --
> > David Booth
> > W3C Fellow / Hewlett-Packard
> > Telephone: +1.617.253.1273
> >

-- 
David Booth
W3C Fellow / Hewlett-Packard
Telephone: +1.617.253.1273
Received on Monday, 3 March 2003 13:25:36 GMT

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