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Subject: Re: [sca-bindings] ISSUE 2 - Callback support over the Web Servicebinding
Hi, Two thoughts here: As per our proposed (but not yet adopted) issues process, issues are not supposed to be discussed until accepted - except insofar as the discussion is towards whether they should be accepted. Second, it looks to me like the email below is digging into a separate issue. And I cannot quite figure out whether it is coupled to ISSUE #2, or genuinely separate. If separate, as issues ed., I'd love to see a separate issue filed.... -Eric. Peshev, Peter wrote: > Hi > > When speaking about redirecting the callback, by API it is possible to > redirect it to another component, whose services could be lacking > binding.ws and instead having only some other binding /*let's say > binding.jms due to the current lack of other bindings in the OASIS TC :) > */. > > If that should be a supported scenario (outbound one binding, inbound > another) that looks that the callbackId-s should be something SCA > specific, and hardly rely on some WS-standard. I am little bit confused > in which TC (java, assembly, bindings) that should be addressed. > > Any thoughts / comments? > > Btw, I personally dislike refirecting the callback since that is > actually dynamic appearance of wires (invocation paths) via java code > usage. > > That introduces hidden dependencies among components, which cannot be > analyzed and displayed by any tooling (except some heuristic code > parsing), cannot be overridden by the assembler via SCDL files and > somewhat hinders the main focus of component reuse and SOA. In addition > such dynamic redirecting is likely to complicate any implementation > which spans beyond one JVM. > > > Best Regards > Peter > > > -----Original Message----- > From: Simon Nash [mailto:NASH@uk.ibm.com] > Sent: Tuesday, 2. October 2007 13:51 > To: sca-bindings@lists.oasis-open.org > Subject: Re: [sca-bindings] ISSUE 2 - Callback support over the Web > Service binding > > Using the wsa:ReplyTo header for the callback endpoint does not seem to > exactly match SCA callback semantics, which allow callback messages to > be > directed to a different endpoint from the endpoint that receives the > reply > to the original request (by calling setCallbackObject() with a > ServiceReference). Using wsa:ReplyTo also requires a message ID to be > added to the original request and the same message ID to be returned on > the reply and any callbacks in the wsa:RelatesTo header. This is more > of > an observation than a problem, though it does require extra state to be > maintained for the message IDs being exchanged. > > In Tuscany, we did not use wsa:Reply To. Instead we used the > WS-Addressing wsa:To endpoint reference with reference parameters to > represent the callback endpoint (as a wsa:EndpointReference), the > callback > ID, and the conversation ID for stateful callbacks. > > I did not propose a specific solution when opening this issue because I > wanted to open this up to as many suggestions and options as possible. > The > discussion around wsa:ReplyTo has been interesting. Perhaps someone > will > have an idea on we can overcome the semantic mismatch that I mentioned > above. I agree that defining a new header for SCA callbacks would be > undesirable. Even the use of SCA-specific reference parameters seems > less > than ideal, but without them I'm not sure how additional information > like > the callback ID could be transmitted. We can't use wsa:MessageID for > this, because of the statement in the WS-Addressing spec that "No two > messages with a distinct application intent may share a [message id] > property." Perhaps the callback ID could be mapped into a wsa:MessageID > > by adding a unique discriminator, so different callback requests could > use > distinct message IDs from which the same callback ID could be extracted. > > Simon > > Simon C. Nash, IBM Distinguished Engineer > Member of the IBM Academy of Technology > Tel. +44-1962-815156 Fax +44-1962-818999 > > > > Khanderao Kand <khanderao.kand@oracle.com> > 01/10/2007 22:47 > > To > Michael Rowley <mrowley@bea.com> > cc > sca-bindings@lists.oasis-open.org > Subject > Re: [sca-bindings] ISSUE 2 - Callback support over the Web Service > binding > > > > > > > Michael Rowley wrote: > >> One problem with using WS-Addressing wsa:ReplyTo is that it is usually >> used to send the response message of a request/response pair. I don't >> think that WS-Address forbids its use for subsequent messages >> (callbacks), but it would at least be unconventional. >> >> > [khanderao] IMHO WS-Addressing does not make any assumptions on the > number of returned messages. It is upto the integration scenario to have > > one or many. > >> However, if we can't use wsa:ReplyTo, that would seem to imply that we >> have to devise our own header to use, but that would be getting >> dangerously close to inventing a wire-level protocol, which we don't >> want to be doing. >> >> > [khanderao] Introducing SCA specific correlation / replyTo parameters > would not be essential. As far as possible we should be using the > available standards, like WSA / WS-Coordination etc.. > >> Michael >> >> -----Original Message----- >> From: Eric Johnson [mailto:eric@tibco.com] >> Sent: Monday, October 01, 2007 12:16 PM >> To: sca-bindings@lists.oasis-open.org >> Subject: Re: [sca-bindings] NEW ISSUE: Callback support over the Web >> Service binding >> >> Created as: http://www.osoa.org/jira/browse/BINDINGS-2 >> >> -Eric. >> >> Simon Nash wrote: >> >> >>> TARGET: >>> >>> Web Service Binding specification, section TBD >>> >>> DESCRIPTION: >>> >>> The Web Service binding provides no example or suggestion for how SCA >>> > > >>> callback semantics could be carried over Web services. There is an >>> example in section 2.2.3 for how conversation semantics could be >>> supported. It would be good to give some guidance (somewhere in the >>> >>> >> range >> >> >>> between example and normative) for what could be done for callbacks. >>> >>> >> One >> >> >>> possibility is to make use of the capabilities provided by >>> >>> >> WS-Addressing. >> >> >>> PROPOSAL: >>> >>> None yet. >>> >>> >>> >>> >>> >>> >>> Unless stated otherwise above: >>> IBM United Kingdom Limited - Registered in England and Wales with >>> >>> >> number >> >> >>> 741598. >>> Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire >>> > PO6 > >> 3AU >> >> >>> >>> >>> >>> >>> > > > > > > > > > Unless stated otherwise above: > IBM United Kingdom Limited - Registered in England and Wales with number > > 741598. > Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 > 3AU > > > > > > >
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