- From: David Booth <dbooth@w3.org>
- Date: Mon, 03 Mar 2003 13:47:39 -0500
- To: Francis McCabe <fgm@fla.fujitsu.com>
- Cc: www-ws-arch@w3.org
And let's call your second definition "frank-2": Definition frank-2 http://lists.w3.org/Archives/Public/www-ws-arch/2003Mar/0023.html Synchronous activity An activity involved in a synchronous rendezvous may assume that the rendezvous is complete for both sides if it 's side completes. At 09:10 AM 3/3/2003 -0800, Francis McCabe wrote: >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 13:47:53 UTC