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Subject: Re: [ws-rx] i089 proposal
Doug I still haven't quite worked through the changes in your latest proposal, but the model of opening up a back channel with a one-way call certainly sounds interesting and worth further pursuit. I think the fundamental difference between our proposals is the context under which a "client" can retrieve messages from a server. In my proposal that context is always a sequence, and therefore - logically - the sequence must exist. For the sequence to exist it either has to be created by the "server" using some other back-channel - or the "client" has to offer it. The Offer model seems much more likely though I don't want to rule out other mechanisms. In your proposal the "context" under which the client retrieves messages (and also the server buffers them) is an EPR. While I quite like the IBM proposal I believe it is a much more general proposal than the proposal that WSO2 has offered. You wish to maintain the ability for an RMS - even a server RMS - to create a sequence with an anonymous client's RMD. Can you give some real world scenarios in which this is required: where a server needs to initiate a Sequence with an anonymous client? Because the main scenario that is driving WSO2 is very simple. The anon client creates and offers a sequence and interacts under those two sequences. In contrast I consider it an important aspect of the specification that all buffering of messages takes place under a sequence and corresponding sequence identifier. So while I don't rule out the server using some existing back channel to create a sequence, I think the simplest model is for the client to offer a sequence and the server to buffer messages under the context of that sequence as it does today. I personally see that requiring the server to buffer messages associated with EPRs but not with sequences to be a major change to the protocol and processing model. In summary, the IBM proposal is a very neat proposal for a reasonably generic solution to the anonymous client problem. It seems much more wide ranging than the proposal we have offered and has much greater implications for an implementation of WSRM. However, it also provides more flexibility and supports a more wide ranging set of potential models. It's simply that we have not yet seen any demand for those models in the RM scenarios we have seen. Paul Doug Davis wrote: > > I do believe that the scenario you're talking about is a required > one but I would phrase it > a bit differently. An RMS (whether its the client-side RMS or the > server-side RMS) needs > to be able to follow the same RM processing model. And part of the > processing model > is the ability to decide "if", "when" and "how" to use RM. As we talk > about in the Q&A > section of our proposal, an RMS having the option of choosing to > decide which RM sequence > to use, when to create new ones, or even when to use RM at all are all > part of the RM > processing model and those aspects need to be maintained even in these > anon cases. > In your proposal you put the burden on the RMD to make a lot > decisions on behalf of > the RMS, that's quite a change to the RM processing model and I have > no idea how the > RMD could ever know all it would need to know to make those decisions. > For example, how > would it know when a new sequence is needed by the RMS? That is why I > believe our > proposal is a better fit for RM - it allows the RMS to retain all of > the same logic and choices > that it has in the async world. Our proposal simply re-establishes > the backchannel that > the RMS (on the server side) is looking for - nothing more. Once that > is there, it is then > back to "standard operating procedures" - the RMS can do whatever it > would normally > do. > thanks, > -Doug > > > > *Paul Fremantle <paul@wso2.com>* > > 04/27/2006 05:51 PM > > > To > Marc Goodner <mgoodner@microsoft.com> > cc > wsrx <ws-rx@lists.oasis-open.org> > Subject > Re: [ws-rx] i089 proposal > > > > > > > > > > If the TC isn't attached to this scenario then this section can be > deleted. The scenario is simply when you want to send unreliably but > receive reliable responses. I've heard this stated as a requirement in > some scenarios, but WSO2 doesn't have any pressing scenarios of this ilk > so we would be happy either way. > > Paul > > Marc Goodner wrote: > > So is an RMS engaged at the client side or not? This is weird, why would > > the infrastructure on the client side decide to do this? > > > > Marc Goodner > > Technical Diplomat > > Microsoft Corporation > > Tel: (425) 703-1903 > > Blog: http://spaces.msn.com/mrgoodner/ > > > > > > -----Original Message----- > > From: Paul Fremantle [mailto:paul@wso2.com] > > Sent: Thursday, April 27, 2006 12:57 PM > > To: Marc Goodner > > Cc: wsrx > > Subject: Re: [ws-rx] i089 proposal > > > > Marc > > > > This is the case where the client is making an offer but not creating an > > > > outbound sequence - thats all. A client offers a sequence, and then > > reliably gets messages from the server that are buffered under that > > sequenceID. > > > > Paul > > > > Marc Goodner wrote: > > > >> I still don't understand why offered sequence is being used in the > >> explanation. If this is going to usually be used with an offered > >> sequence I'd like to understand how, that isn't explained in my mind. > >> > > If > > > >> it is applicable for any sequence, offered or not, I'd like to > >> understand that as well. The current text only confuses me in its use > >> > > of > > > >> the term and I'm afraid your explanation below isn't helping me get > >> > > past > > > >> it. Perhaps comparing the two modes would be a better approach. > >> > >> On 4.2, "Offer a sequence without the overhead of requesting one"? I > >> don't understand. The text refers to the RMD requesting a sequence > >> > > from > > > >> the RMS, but it sounds like this is an unreliable request so doesn't > >> that mean there is no RMS at the client? Isn't this about the service > >> acting as an RMS and the client acting as an RMD? So the pattern would > >> be client sends one way message to service (GetMessage?), response is > >> Offer, then client sends a response to the response of Accept? What > >> > > does > > > >> the service return to that? Why wouldn't the service send a CS in the > >> body of the GetMessage response to the client? > >> > >> Marc Goodner > >> Technical Diplomat > >> Microsoft Corporation > >> Tel: (425) 703-1903 > >> Blog: http://spaces.msn.com/mrgoodner/ > >> > >> > >> -----Original Message----- > >> From: Paul Fremantle [mailto:paul@wso2.com] > >> Sent: Monday, April 24, 2006 1:11 AM > >> To: Marc Goodner > >> Cc: wsrx > >> Subject: Re: [ws-rx] i089 proposal > >> > >> Marc > >> > >> I use the words "Offered Sequence" informatively and non-normatively. > >> This is most likely to be used with an offered sequence, but isn't > >> > > tied > > > >> to that. > >> > >> As regards 4.2, this is there to satisfy the scenario where you only > >> want reliable responses. I added this in for discussion because I know > >> > > > > > >> that some members find this an important scenario. In that case you > >> > > need > > > >> to be able to Offer a sequence without the overhead of requesting one. > >> > > > > > >> It is related to the anonymous client because without a real endpoint > >> the server cannot send a CS to the client so it relies on an offer. > >> > >> Paul > >> > >> Marc Goodner wrote: > >> > >> > >>> Given 1 and 2, yes some text that clarified that not only is this > >>> specific to RM but that a general solution would be preferable would > >>> > >>> > >> be > >> > >> > >>> best. > >>> > >>> On 3 I suppose, I don't like seeing WS-A headers in the body of a > >>> message though. Do you really even need the response for a specific > >>> message? Why not return any responses or messages for that sequence > >>> > >>> > >> that > >> > >> > >>> have not been acknowledged? And what are you talking about when you > >>> > >>> > >> say > >> > >> > >>> this is tied to the offered sequence? What offered sequence? I don't > >>> > >>> > >> see > >> > >> > >>> anything here that ties the use of your GetMessage proposal to an > >>> offered sequence. > >>> > >>> I don't understand section 4.2 in your proposal at all. What does > >>> > > this > > > >>> have to do with the rest of this proposal? > >>> > >>> Marc Goodner > >>> Technical Diplomat > >>> Microsoft Corporation > >>> Tel: (425) 703-1903 > >>> Blog: http://spaces.msn.com/mrgoodner/ > >>> > >>> > >>> -----Original Message----- > >>> From: Paul Fremantle [mailto:paul@wso2.com] > >>> Sent: Thursday, April 20, 2006 1:57 AM > >>> To: Marc Goodner > >>> Cc: wsrx > >>> Subject: Re: [ws-rx] i089 proposal > >>> > >>> Marc > >>> > >>> 1) Yes - I completely aimed this to be a specific model for RM. I > >>> > >>> > >> would > >> > >> > >>> be happy to include language that indicates that if a more general > >>> purpose firewall crossing mechanism was in place this should not be > >>> used. > >>> 2) The wsrm:Identifier is a required part of my proposal, and > >>> > >>> > >> therefore > >> > >> > >>> this proposal is completely tied to the use of RM. > >>> 3) The suggestion of using messageNumber is interesting. The > >>> > >>> > >> motivation > >> > >> > >>> for using a message ID was that there may be situations where I > >>> > > really > > > >>> > >>> > >> > >> > >>> want the response to a given message. We do not - so far - have any > >>> concept of a response to a given RM messageID, so that seemed like a > >>> > >>> > >> new > >> > >> > >>> concept to me, whereas WS-A systems do keep track of responses to > >>> > >>> > >> given > >> > >> > >>> messageIDs. But I'm not averse to your suggestion. However I wish to > >>> make clear that in my proposal you MUST have both the Identifier and > >>> > >>> > >> the > >> > >> > >>> messageID - so it is still very closely tied to the offered sequence. > >>> > >>> Paul > >>> > >>> Marc Goodner wrote: > >>> > >>> > >>> > >>>> I hope that this is scoped to RM and not a general purpose polling > >>>> mechanism. I assume that is your intent in that you use the > >>>> wsrm:Identifier and indicate that you see this being part of the > >>>> > > core > > > >>>> spec. Still it seems like including language that indicates that > >>>> > >>>> > >> would > >> > >> > >>>> be advised, particularly noting that if there were a general purpose > >>>> polling mechanism that it might be preferred over this one. > >>>> > >>>> So following from that why is MessageID in the GetMessage? Isn't the > >>>> identifier enough? If it isn't wouldn't the addition of > >>>> wsrm:MessageNumber do the trick? > >>>> > >>>> Marc Goodner > >>>> Technical Diplomat > >>>> Microsoft Corporation > >>>> Tel: (425) 703-1903 > >>>> Blog: http://spaces.msn.com/mrgoodner/ > >>>> > >>>> > >>>> -----Original Message----- > >>>> From: Paul Fremantle [mailto:paul@wso2.com] > >>>> Sent: Thursday, April 06, 2006 12:40 PM > >>>> To: wsrx > >>>> Subject: [ws-rx] i089 proposal > >>>> > >>>> Folks > >>>> > >>>> At the F2F I took away an action to come up with a proposal for i089 > >>>> > > > > > >>>> before the call. I'm sorry its so close to the call. > >>>> > >>>> I've attached a proposal for review. This is a work in progress, but > >>>> > >>>> > >> I > >> > >> > >>>> > >>>> > >>>> > >>> > >>> > >>> > >>>> think it helps call out some of the issues involved around i089. > >>>> > >>>> I think the most important questions for the TC are: > >>>> > >>>> (1) How does a customer/user use WSRM in a two-way scenario if one > >>>> > >>>> > >>>> > >>> side > >>> > >>> > >>> > >>>> is anonymous? > >>>> (2) Adding a "GetMessage" makes the protocol more symmetric, but > >>>> > > also > > > >>>> > >>>> > >> > >> > >>>> might overlap with a wider non-reliable solution to this problem. Is > >>>> > >>>> > >>>> > >>> it > >>> > >>> > >>> > >>>> in the scope of this TC to add this? > >>>> (3) In the case we do add it, what criteria do we use to select > >>>> > > which > > > >>>> > >>>> > >> > >> > >>>> message to request. > >>>> (4) Is this a generic solution (i.e. can the RMD request messages > >>>> > >>>> > >> from > >> > >> > >>>> > >>>> > >>>> > >>> > >>> > >>> > >>>> the RMS in all cases) or special cased to anonURI scenarios? > >>>> > >>>> Paul > >>>> > >>>> > >>>> > >>>> > >>>> > >>> > >>> > >>> > >> > >> > > > > > > -- > > Paul Fremantle > VP/Technology, WSO2 and OASIS WS-RX TC Co-chair > > http://feeds.feedburner.com/bloglines/pzf > paul@wso2.com > > "Oxygenating the Web Service Platform", www.wso2.com > > -- Paul Fremantle VP/Technology, WSO2 and OASIS WS-RX TC Co-chair http://feeds.feedburner.com/bloglines/pzf paul@wso2.com "Oxygenating the Web Service Platform", www.wso2.com
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