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Subject: RE: FW: T2, Proposed solution for ... Re: SyncReplyandReliableMessagingMethod in QualityOfServiceInfo
Comments below. Regards, Marty ************************************************************************************* Martin W. Sachs IBM T. J. Watson Research Center P. O. B. 704 Yorktown Hts, NY 10598 914-784-7287; IBM tie line 863-7287 Notes address: Martin W Sachs/Watson/IBM Internet address: mwsachs @ us.ibm.com ************************************************************************************* David Fischer <david@drummondgroup.com> on 09/21/2001 12:10:59 PM To: Chris.Ferris@Sun.COM, ebxml-msg@lists.oasis-open.org cc: Subject: RE: FW: T2, Proposed solution for ... Re: SyncReply andReliableMessagingMethod in QualityOfServiceInfo Chris, Does this mean communications between two Trading Partners is ALWAYS RM or NEVER RM? We've already decided DeliveryChannel is address specific so there cannot be two DeliveryChannels between one set of addresses. MWS: There certainly be two or more delivery channels with the same endpoint address. All but one have to be associated with specific (different) business transactions. These are defined in the override element. In any case, one can always associate different endpoint addresses with delivery channels even though they go to the same physical place (different URIs with the same IP address). Does this mean the RM settings are fixed and never changing between these two Trading Partners? Doesn't sound very flexible. Some documents will be critical and thus require RM while some do not. How do we accommodate this? MWS: We don't have anything in the CPA that specifies anything per instance of a message. I don't know how that could be done. I don't think that the BPSS provides this capability either. Anything that has to be per instance of a message has to be done through information in the message header. The application has to specify this information. Chris wrote: How does this work if the sending MSH knows nothing of intermediaries? Are you suggesting that the Via element is now REQUIRED on all messages? In the case of single-hop, no retryCount is necessary. I have to agree though, how does the sender know this is single-hop? Since there is always the potential of transparent IMs, shouldn't we assume that nothing is single-hop and therefore Via is ALWAYS required for RM? On the issue of an MSH knowing it is an IM, this decision has to be made at the MSH layer since security is an MSH layer function (see figure 6-1). If you wait, the MSH will try to validate the signature (or decrypt) and fail thus sending an error message back to the From Party. Again, message packaging and security are in the MSH, not the Application*. The MSH MUST know it is an IM. Packaging and forwarding are MSH functions, not application. *A different set of criteria might apply to an intra-company mailroom situation. Regards, David Fischer Drummond Group. -----Original Message----- From: Chris.Ferris@Sun.COM [mailto:Chris.Ferris@Sun.COM] Sent: Friday, September 21, 2001 9:25 AM To: ebxml-msg@lists.oasis-open.org Subject: Re: FW: T2, Proposed solution for ... Re: SyncReply andReliableMessagingMethod in QualityOfServiceInfo Dan Weinreb wrote: > > Date: Thu, 20 Sep 2001 16:45:07 -0500 > From: David Fischer <david@drummondgroup.com> > > From: Chris.Ferris@Sun.COM [mailto:Chris.Ferris@Sun.COM] > Sent: Thursday, September 20, 2001 11:50 AM > > How does this work if the sending MSH knows nothing of intermediaries? > Are you suggesting that the Via element is now REQUIRED on all messages? > > <df>Yes, this is a problem, not only for retryCount but for all parameters in > Via. I have asked this same question before, is Via always required? If we are > doing RM at all, then Via is required in order to pass the ackRequested and > reliableMessagingMethod parameters. I guess Via is REQUIRED for all RM > messages -- regardless of retryCount. > </df> Here, I disagree. The parties to a single-hop exchange can via the CPA "know" whether the message is being sent via ebXML RM and hence there is no need whatsoever for ackRequested. Again, I want to make it clear that the "CPA" is a "virtual CPA" in the sense that there is an understanding between the parties that is shared whether by means of a physical CPA or otherwise. I think you know my preference;-) > > Right, the question is whether it's an RM transmission or not. > > Every hop in a communication is either using ebXML RM or not: ebXML RM > is being used if (a) this is supposed to be a reliable communication > and (b) reliableMessageMethod says that the reliability is done with > ebXML RM rather than by the transport layer. > > Even if there is no IM, there is still one hop, and the hop is either > using ebXML RM or not. > > How does an intermediary distinguish itself as such? > > <df>The IM must know that it is an IM in order to forward rather than process > the payload. If the IM is not the From Party or the To Party then it must be an > IM. This is not quite true for a mailroom situation (need to work on this -- > something like MTA routing tables? or MX records?). > </df> Again, I disagree here. I think of an MSH as being unaware of the fact that it is anything but a MSH. The IM-ness of a node is captured in application logic as we have discussed, not as an aspect of the MSH itself. IMO, the fact that intermediary functionality is being applied by the "routing app" is no different than if the "application" were a responding application of a true endpoint. I suppose that the MSH node could detect that the ToParty is not itself and apply a different set of logic, but again, this seems to be a bit more complexity than might be needed otherwise. RoutingApp ^ | | V MSH-in MSH-out > > And whenever a hop happens, the MSH's at each end of the hop have to > "know" somehow what the reliableMessageMethod parameter is, so that > they know whether to talk ebXML RM or not. Agreed. > > retryInterval applies to the RM retry. You are now stating that the DR is the RM > artifact, not the Acknowledgment. What happens when no DR is requested/required? > Does the sending MSH wait for the response message? > > <df>Chris, you are right, almost. There is a CPA to the first IM and a CPA with > the end. > > If we're going to be using CPA's this way, I think the CPA is going to > need some work. Agreed. This is a known issue. > > The overall idea of the CPA is that you examine what business process > you're doing, what role you're in, and what service and action you're > performing; you submit this to the CPA, and it gives you back a > DeliveryChannel and a Packaging. DeliveryChannel, in turn, give you > a Transport and a DocExchange, plus some parameter values. > > The information in Transport is only relevant to hop-to-hop > communications; it's meaningless to ask for, say, the TCP address of > the To Party when there are IM's, since the From Party doesn't talk > directly to the To Party. > > The information in Packaging is all about the payload, and so it's > only relevant to end-to-end communications; IM's don't pay attention > to the contents. > > How about the parameters in DeliveryChannel, and DocExchange? It > looks to me like they are about the communication as a whole, i.e. all > the hops, but this perhaps should be clarified. Supposed to be. > > Should the IM's really be looking at the Service and Action fields of > the message, and looking through the Override elements of a CPA, in > order to decide what parameters to use? ---------------------------------------------------------------- To subscribe or unsubscribe from this elist use the subscription manager: <http://lists.oasis-open.org/ob/adm.pl> ---------------------------------------------------------------- To subscribe or unsubscribe from this elist use the subscription manager: <http://lists.oasis-open.org/ob/adm.pl>
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