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Subject: RE: [ws-rx] i089 proposal


 
I think that in your proposal, renaming GetMessage to anything that conveys the technical intent of establishing a backchannel makes sense. Perhaps this will also help in comparing the two current polling based proposals!
-- Sanjay


From: Doug Davis [mailto:dug@us.ibm.com]
Sent: Friday, Apr 28, 2006 20:16 PM
To: ws-rx@lists.oasis-open.org
Subject: RE: [ws-rx] i089 proposal


+1 - well stated.  Its the special cases and changes to the RM processing model we're trying to minimize.

Gil - was thinking about your questions on the call yesterday regarding whether GetMessage should be modeled as a one-way or request/response.  While its a superficial change, I was wondering if we renamed GetMessage to something else, like EstablishConnection, if that would make it more palatable?  This would make it clearer that we're not performing some kind of query but rather we're just trying to reconnect the two endpoints.  

thanks,
-Doug



"Gilbert Pilz" <Gilbert.Pilz@bea.com>

04/28/2006 12:55 PM

To
"Paul Fremantle" <paul@wso2.com>
cc
<ws-rx@lists.oasis-open.org>
Subject
RE: [ws-rx] i089 proposal





Paul,

To be fair, I don't think its primary intent of Doug's proposal is to be
more "wide ranging". It appears that the goal of this proposal is to
minimize the amount of special case code that needs to be added to the
RMD to support non-reachable clients. Pushing the polling correlator
"down" into the EPR allows the server-side RMS to operate just like any
other RMS without having to be aware of the fact that the RMD is on an
unreachable client.

I think we need to come to a consensus about the motivations behind
Doug's proposal. How many special cases does your proposal call for? How
important is it to avoid having to make those special cases?

- gp

> -----Original Message-----
> From: Paul Fremantle [mailto:paul@wso2.com]
> Sent: Friday, April 28, 2006 4:41 AM
> Cc: ws-rx@lists.oasis-open.org
> 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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