I believe the challenge of the multiple RMD-clients
is more for the RMS-server about associating the [offered] sequenceIDs with
their respective RMDs. Once this done, Paul has no more problems with subsequent
instances of the in/out pattern: correlation between in / out is supported
by WS stack as done for non-reliable exchanges.
Now he still has a problem with the Notify
kind of exchange (out only) as you said before: that’s a use case
discussion (how much do we want to support that case?).
Back to the the wsrm:Offer/wsrm:Endpoint, regardless whether we
use it or not, it appears that the wording in the spec excludes the use of this
offered sequence for multiple endpoints – at least excludes multiple RMD
endpoints for that seq. In that case we can still stick to [1 seq à 1 RMD] and the RMD can safely
pull based on sequence Id.
Now, what should go in this wsrm:Endpoint element could be the
response to the identification of the RMD-client – couldn’t this be
the same as the EPR you recommend to use with the */polling URI in your
proposal?
Jacques
From: Doug Davis
[mailto:dug@us.ibm.com]
Sent: Thursday, May 04, 2006 7:13
PM
To: ws-rx@lists.oasis-open.org
Subject: RE: [ws-rx] Minimalist
GetMessage proposal: the anon use case
Maybe I didn't follow the thread but I thought the
problem related to how, when a
client
sends a GetMessage, does the server know which client is sending the
message?
It can't just send any message in the sequence to any client who
happens
to be an RMD for that sequence. If the RMD spans multiple endpoints
the
server needs to make sure that the messages for clientA go to clientA and
not
clientB. SequenceID alone isn't enough - so what other correlation does
Paul's
proposal use? Or is the answer that Paul's solution only works for
one
endpoint per sequence? If so, we have yet another restriction on the
use-cases
that
it supports.
-Doug
|
"Marc Goodner"
<mgoodner@microsoft.com>
05/04/2006 09:22 PM
|
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To
|
Doug Davis/Raleigh/IBM@IBMUS,
<ws-rx@lists.oasis-open.org>
|
|
cc
|
|
|
Subject
|
RE: [ws-rx] Minimalist GetMessage proposal:
the anon use case
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So how does telling the other side
where to send the RM protocol messages not solve the problem you perceive Doug?
Marc Goodner
Technical Diplomat
Microsoft Corporation
Tel: (425) 703-1903
Blog: http://spaces.msn.com/mrgoodner/
From: Doug Davis
[mailto:dug@us.ibm.com]
Sent: Thursday, May 04, 2006 6:17 PM
To: ws-rx@lists.oasis-open.org
Subject: RE: [ws-rx] Minimalist GetMessage proposal: the anon use
case
If I remeber correctly, that part of the spec just tells the other side where
to send RM protocol messages to for the Offered sequence - since it otherwise
has no idea where they go.
-Doug
|
"Durand,
Jacques R." <JDurand@us.fujitsu.com>
05/04/2006 07:39 PM
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To
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Doug Davis/Raleigh/IBM@IBMUS,
<ws-rx@lists.oasis-open.org>
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cc
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|
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Subject
|
RE: [ws-rx] Minimalist GetMessage proposal:
the anon use case
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That crossed my mind too…
But then the spec seems to rule that case out in case of offered sequences,
given the exclusive scoping to one endpoint assumed by: wsrm:Offer/wsrm:Endpoint
(WD12, Line283)
Jacques
From: Doug Davis [mailto:dug@us.ibm.com]
Sent: Thursday, May 04, 2006 3:53 PM
To: ws-rx@lists.oasis-open.org
Subject: RE: [ws-rx] Minimalist GetMessage proposal: the anon use
case
I'm a bit lost - too much email on this today :-) but even if there as a
wsrm:Identifier
in a message that doesn't tell you which client it is since a sequence can span
multiple endpoints.
-Doug
|
"Durand,
Jacques R." <JDurand@us.fujitsu.com>
05/04/2006 03:17 PM
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To
|
"Paul Fremantle"
<paul@wso2.com>
|
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cc
|
"wsrx" <ws-rx@lists.oasis-open.org>
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Subject
|
RE: [ws-rx] Minimalist GetMessage proposal:
the anon use case
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|
- The case reliable-in/reliable-out works quite well, provided the RMS
does the correlation between initial sequence and offered seq, as
recommended in 4.2.
- The case unreliable-in/reliable-out seems to need the "hint" you
mention in 4.2., plus some other way to offer a sequence than the CS
carrier.
In any case, the many-anonymous(RMD)clients- to-one-(RMS)server appears
to be quite a common case (many users of the same WS instance), to
justify adding back 4.2 in your proposal...
Jacques
-----Original Message-----
From: Paul Fremantle [mailto:paul@wso2.com]
Sent: Wednesday, May 03, 2006 11:15 PM
To: Durand, Jacques R.
Cc: wsrx
Subject: Re: [ws-rx] Minimalist GetMessage proposal: the anon use case
Jacques
You are quite right. This is an interesting situation. One of the
problems is that we do not in this spec define how messages are
allocated to sequences. The IBM proposal simply shifts this problem to
the EPRId as you point out.
In one of my own early drafts of the proposal I had these words in
section 4.2, but I removed them for simplicity. However, if they are
useful they could be added back.
"The WSRM specification does not define the allocation of messages to a
sequence. In the case of reliable request-response with an anonymous
client, the server MAY make a correlation between an incoming sequence
and an offered sequence. In the case where the request message is
unreliable, and the client is anonymous, there might not be a clear
basis to allocate messages to a given sequence. In this scenario the
client MAY add the <wsrm:Identifier> of the offered sequence as a SOAP
Header element or elsewhere in the message as a hint to the server."
Paul
Durand, Jacques R. wrote:
> Paul:
>
> Are you sure this works when two different (un-addressable) clients
are
> sending an anonymous wsrm:Offer/wsrm:Endpoint to the same RMS-to-be
> endpoint, say for offering sequences S1 and S2?
> The offered sequences S1 and S2 have to be clearly associated from the
> start with the right client-RMD, by the server-RMS.
> With an in/out pattern where the in message is not sent reliably, how
> would the server-RMS know if it should use S1 or S2 when sending the
out
> message for an in message of one of the two initiators?
> Don't we still face the same issue of distinguishing anonymous
endpoints
> that IBM proposal tries to address ( with wsrm:EPRid) ?
> (Do I miss something?)
>
> Jacques
>
> -----Original Message-----
> From: Paul Fremantle [mailto:paul@wso2.com]
> Sent: Wednesday, May 03, 2006 12:05 PM
> To: wsrx
> Subject: [ws-rx] Minimalist GetMessage proposal
>
> Based on some of the discussions it seemed to me that it could be
> valuable to produce a completely "minimalist" GetMessage
proposal.
>
> This is a new proposal that is based on the previous WSO2 proposal.
>
> The proposal removes the MessageID selector in the GetMessage -
relying
> on simply getting whatever message the server sends back next.
>
> Also it removes the section 4.2. Effectively section 4.2 is an
> optimisation: for example to support unreliable-in/reliable-out a
client
>
> could do a createsequence+offer and never use the outgoing sequence.
In
> this case there is an overhead, which 4.2 aimed to remove, but this
> simplifies the proposal by focussing on the bare minimum required to
> support the most common use cases, but still allowing the other use
case
>
> with a slight overhead.
>
> I've also included a sample message flow which I hope helps understand
> the proposal and show the general usage.
>
> 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