- From: Assaf Arkin <arkin@intalio.com>
- Date: Thu, 27 Feb 2003 12:46:28 -0800
- To: "Christopher B Ferris" <chrisfer@us.ibm.com>, "David Orchard" <dorchard@bea.com>
- Cc: <www-ws-arch@w3.org>, <www-ws-arch-request@w3.org>
- Message-ID: <IGEJLEPAJBPHKACOOKHNAEFHDEAA.arkin@intalio.com>
+1 arkin -----Original Message----- From: www-ws-arch-request@w3.org [mailto:www-ws-arch-request@w3.org]On Behalf Of Christopher B Ferris Sent: Thursday, February 27, 2003 10:04 AM To: David Orchard Cc: www-ws-arch@w3.org; www-ws-arch-request@w3.org Subject: RE: Sync Definition #2 (corrected) Appologies if these definitions have not already been proposed, the thread is simply too long for me to catch up:) 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. I believe that we could extend these definitions to whole conversations as well. Cheers, Christopher Ferris Architect, Emerging e-business Industry Architecture email: chrisfer@us.ibm.com phone: +1 508 234 3624 "David Orchard" <dorchard@bea.com> Sent by: www-ws-arch-request@w3.org 02/27/2003 11:41 AM To <www-ws-arch@w3.org> cc Subject RE: Sync Definition #2 (corrected) What classifies as "wait for a response"? I typically think of a synchronous definition as "a programmatic flow of control on the sender effectively does nothing but wait for a response after sending it's request". And before everybody goes gaga over showing edge cases that are asynch that have flow of control, or multiple flows of control that are synch, that's not the real issue. The point is that synchronicity typically has the notion of *something* blocking and waiting for the response. Another approach is to couple synchronicity with connections. So synchronous is where the request and response flow forwards and backwards over the same virtual connection between the sender and receiver. Of course, it's possible to have synch interactions over non-synch connections, which is why I think that synchronicity is more of a feature of program logic than bits on the wire. Hey look, textual suggestion and only 8 sentences of prose. Cheers, Dave -----Original Message----- From: www-ws-arch-request@w3.org [mailto:www-ws-arch-request@w3.org]On Behalf Of Assaf Arkin Sent: Wednesday, February 26, 2003 10:42 PM To: Walden Mathews; Ugo Corda; www-ws-arch@w3.org Subject: RE: Sync Definition #2 (corrected) I just love permutations ;-) Seriously. In order to say that something is synchronous you need to say what it is that's synchronous. The definition given below only describes a synchronous (request/response) operation but doesn't describe an asynchronous (input-only or output-only) operation, so it's only half way there. We still need to describe asynchronous operations. And it describes the operation based on how the protocol works, which is interesting and important, but still says nothing about the operation itself. arkin -----Original Message----- From: Walden Mathews [mailto:waldenm@optonline.net] Sent: Wednesday, February 26, 2003 7:29 PM To: Assaf Arkin; Ugo Corda; www-ws-arch@w3.org Subject: Re: Sync Definition #2 (corrected) Arkin, I don't understand where your fascination with these permutations is coming from. I thought the goal was to define the two terms, one definition each, and let it go at that (if possible). Walden ----- Original Message ----- From: Assaf Arkin To: Ugo Corda ; www-ws-arch@w3.org Sent: Wednesday, February 26, 2003 3:51 PM Subject: RE: Sync Definition #2 (corrected) Actually, yours can be easily phrased in terms of mine: A synchronous interaction (= reqeust/response) is communicated asynchronously when the request and response are chronologically decoupled. In other words ... A synchronous interaction is communicated synchronoulsy if the reverse could be said. Which of course begs the question, what about an asynchronous interaction. Say I just send a message but don't expect a response? An asynchronous interaction (= send or receive) is communicated asynchronoulsy when the sender does not have to wait for the receiver to receive the message. An asynchronous interaction is communicated synchronoulsy if the reverse could be said. arkin -----Original Message----- From: Ugo Corda [mailto:UCorda@SeeBeyond.com] Sent: Wednesday, February 26, 2003 12:46 PM To: Assaf Arkin; www-ws-arch@w3.org Subject: RE: Sync Definition #2 (corrected) Well, it's a matter of definitions, and evidently yours does not correspond to mine. I hope people will vote soon so that we can put this issue behind ... Ugo -----Original Message----- From: Assaf Arkin [mailto:arkin@intalio.com] Sent: Wednesday, February 26, 2003 12:15 PM To: Ugo Corda; www-ws-arch@w3.org Subject: RE: Sync Definition #2 (corrected) I think you have just defined a synchronous interaction (request/response, see formal definition) in terms of an asynchronous transport (i.e. one that does send and receive actions independently). arkin -----Original Message----- From: www-ws-arch-request@w3.org [mailto:www-ws-arch-request@w3.org]On Behalf Of Ugo Corda Sent: Wednesday, February 26, 2003 7:36 AM To: Ugo Corda; www-ws-arch@w3.org Subject: RE: Sync Definition #2 (corrected) 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.
Received on Thursday, 27 February 2003 15:48:41 UTC