Yes Doug, anonymous is
clearly defined in WS-A. Here is a rather key line, “The precise meaning
of this URI is defined by the binding of Addressing to a specific protocol
and/or the context in which the EPR is used.” In the SOAP binding part of
WS-A it only talks of SOAP 1.1 and 1.2, it does not speak to any other
protocols that may be within the context of a specific EPR. Your interpretation
as I understand it from your suggestions that we define our own anonymous uri
is that we refrain from composing fully with WS-A. To me that is tantamount to
saying that there are fundamental flaws in WS-A. I for one don’t believe
that. Lets just focus on what if anything needs to be clarified regarding the
use of composing WS-RM properly with WS-A including anonymous uri. That would
be a better use of our time rather than trying to justify defining our own uri
with the same semantics.
I’d also like
to point out that the default value for ReplyTo is anonymous, particularly if
it is not present. So your proposal to forbid the use of anonymous is that only directly addressable clients will be
able to use WS-RM. I think WS-RM is particularly relevant to clients on
unreliable networks. A characteristic of many clients on such networks is that
they are unlikely to be directly addressable. I don’t find it to be an
acceptable solution to write off that class of clients from using WS-RM. Your
proposal to me seems to contradict one of the fundamental motivating use cases
for WS-RM.
Finally through all
of this I still maintain that i089 should be closed with no action. I still have
not heard anything that needs to be said in the spec about the overall use of
anonymous.
CIL.
From: Doug Davis
[mailto:dug@us.ibm.com]
Sent: Tuesday, March 14, 2006
10:38 AM
To: Marc Goodner
Cc: ws-rx@lists.oasis-open.org
Subject: RE: [ws-rx] AnonURI and
Offer and WS-Addressing
The WSA spec is very clear what anon replyTo means -
this is a contract that both the client and server need to follow. This
means that (for anon replyTo + HTTP) the server MUST send it back on
'this http response' and that the client MUST look for it on 'this http
response'. Sending it back on some other http connection, or looking for
it on some other http connection is not compliant with WSA's defintion of what
anon ReplyTo means. Composing RM into the picture can not change what WSA
says - RM can cause the messages to be resent but for any individual message
exchange the WSA rules must be adhered to.
I
believe all of the options I listed are valid - spec wise. You can
dislike some of them but I believe that are all compliant with WSA.
Marc said: On point 3 I see that as being
different only if you’ve only been looking at this from a point of view
of 1 way messages exclusively. If you get an ack for a request you sent without
the corresponding response you obviously still have the request available for
retransmitting. I don’t see the difficulty. I don’t see how out
only applies in this discussion though.
You
'obviously still have the request' only until the request is acked. After
that point the RM spec does not manadate anything - so replaying an ACked
message, as I said, is something I believe is new to most people. 'Out
only' applies because I'd like our RM to be used in more than the most simple
of use-cases.
MG: New but hardly confusing. I
still don’t understand how out only applies in this discussion. In fact
you don’t identify any issues yourself. If you aren’t aware of any
issues then why are you suggesting there are any? I suggest it isn’t
relevant until you actually identify an issue with it.
Marc
said: On point 4 you seem to have an async response in mind. In a synchronous
req/resp MEP the ack for the request message would be on the response message.
The thing we’re discussing is what to do when that response message is
lost and the ack is detected in a ack range on a subsequent response message to
the client. It helps to think of this without complications. Imagine that the
request comes in and the response (with the ack) is lost. The client
hasn’t sent any other requests. What does it do? Why it resends the
request. The service should be prepared for this as it never got an ack for the
response either. Just extend that model and it is easy to see that when the
client sees an ack on a response to another message that contains an ack for a
request it never got a response from it can resend the request to get the
unacknowledged response. What is the problem?
The
problem is that the RMS MUST know about the MEP - something we haven't required
up to now, and it links the request and response sequences - something, again,
we haven't done. Once we head down this path I don't see how we can't be
required then to examine how the lifecycle of the two sequences might be
linked. Again, as I've said many times, no one has been able to explain
how the full RM protocol works - for example, how a Close or Terminate can be
sent from the RMD back to the RMS. Or how RM can be used in one
direction but not the other - e.g. non-RM-request/RM-response. The longer
we talk about this the more questions we get.
MG:
I’m sorry Doug but that is a very biased characterization of the severity
of the problem. This worked fine with the spec before Close was added or TS was
changed to add the response leg. I don’t think either are insurmountable
problems. As many other things have been clarified recently in this discussion
around Offer I expect to be able to make a proposal shortly that should address
these problems that have been introduced by some of the new features in the
specification.
thanks,
-Doug
|
"Marc Goodner"
<mgoodner@microsoft.com>
03/14/2006 12:50 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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|
|
Subject
|
RE: [ws-rx] AnonURI and Offer and
WS-Addressing
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I would point out that the definition
of anonymous uri is:
“Some endpoints cannot be located with
a meaningful IRI; this URI is used to allow such endpoints to send and receive
messages. The precise meaning of this URI is defined by the binding of
Addressing to a specific protocol and/or the context in which the EPR is
used.”
The section you quote below is from section
5.1 Use of Anonymous Address in SOAP Response Endpoints. The SOAP 1.2 binding
text you quote does not cover RM, rather it covers a vanilla SOAP 1.2 endpoint
only. WS-A leaves us the flexibility to clarify any points on its use when RM
is in use.
I’m still surprised to see suggestions
to the effect that anon can not be used with RM followed by suggestions that
amount to defining our own anon uri (essential anonymous uri redux). I think it
makes far more sense to clarify any points on the use of anon when the RM
protocol is being used rather than forbid its use as it seems the WS-A WG left
us the latitude to do so. So I disagree with your points 1, 2 and 5 below.
On point 3 I see that as being different only
if you’ve only been looking at this from a point of view of 1 way
messages exclusively. If you get an ack for a request you sent without the
corresponding response you obviously still have the request available for
retransmitting. I don’t see the difficulty. I don’t see how out
only applies in this discussion though.
On point 4 you seem to have an async response
in mind. In a synchronous req/resp MEP the ack for the request message would be
on the response message. The thing we’re discussing is what to do when
that response message is lost and the ack is detected in a ack range on a
subsequent response message to the client. It helps to think of this without
complications. Imagine that the request comes in and the response (with the
ack) is lost. The client hasn’t sent any other requests. What does it do?
Why it resends the request. The service should be prepared for this as it never
got an ack for the response either. Just extend that model and it is easy to
see that when the client sees an ack on a response to another message that
contains an ack for a request it never got a response from it can resend the
request to get the unacknowledged response. What is the problem?
Finally I’d like to point out that this
and many other recent posts conflates i090 and i089 together. I don’t
understand why so much emphasis is being placed on the use of anonymous with an
Offered sequence to simultaneously justify removing Offer and prove that
anonymous should be forbidden when using WS-RM because of perceived problems
when used with Offer.
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: Monday, March 13, 2006 6:03 AM
To: ws-rx@lists.oasis-open.org
Subject: Re: [ws-rx] AnonURI and Offer and WS-Addressing
Paul,
please see: http://dev.w3.org/cvsweb/~checkout~/2004/ws/addressing/ws-addr-soap.html?content-type=text/html;%20charset=utf-8#anonaddress
which is the latest editor's copy of WSA, and in particular:
When "http://www.w3.org/2005/08/addressing/anonymous" is specified
for the response endpoint and the message is the
http://www.w3.org/2003/05/soap/mep/InboundMessage property of a SOAP
request-response MEP [SOAP 1.2 Part 2:
Adjuncts], then any response MUST be the
http://www.w3.org/2003/05/soap/mep/OutboundMessage property of the same
instance of the SOAP request-response MEP [SOAP 1.2 Part 2:
Adjuncts].
They've added quite a bit of clarifying text since the submitted version. I
think the "same instance" part makes it clear that the response MUST
flow over the same http connection as the request.
Perhaps it would help if we summarized the list of options:
1 - prohibit anon replyTo if the response is expected to be sent using RM
2 - prohibit the use of RM when the wsa:To is anonymous - or said another way,
when replyTo is anon the response is not sent using RM
3 - resend request until response is delivered/acked even if the request is
acked
4 - don't ack a request until the response is sent
5 - define a new URI that allows a polling flow like Paul described in his
previous note
Here are some comments on each:
1 and 2 might actually be the same thing but my intention was to say that in
'1' you can't use anon replyTo if the response is sent reliably - so perhaps a
Fault is generated. In '2', if the replyTo is anon then no matter what
the wsdl/policy... says, RM needs to be turned off for the response - it can
still be sent but just not as part of an RM sequence. Slightly different.
'3' is a change to what I believe is most people current view of the RM
processing model because we'll resend ACKed messages. It also will only
work for one-req/one-res MEPs. Out-only, or single-req/multiple-res may
have issues.
'4' is a change to the RM processing model because the RMD will not ACK a
message even if it is received. Depending on how you view things this
could mean that the RMD needs to lie about what it has and could cause messages
to be resent because the RMD is waiting for a response before it will ACK the
request. Now, since the RMD gets to choose when it ACKs (meaning is it
simply 'I got it' or something else it up to it), so to some this may not be
lying but just a change to the ACK model of that RMD.
'5' doesn't require a change to the RM processing model but heads in the
direction of ws-polling and can work w/o a change to the RM processing model
and can work for all MEPs. Even if we did pick this option we'd still
need to say something in the RM spec about what should happen when anon replyTo
is used (I'm guessing 1 or 2).
Are there any other options people think we need to add to the list? Having
all of the known choices in front of us might help focus the discussions.
thanks,
-Doug
|
Paul Fremantle
<paul@wso2.com>
03/12/2006 04:43 AM
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To
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Bob Freund-Hitachi
<bob.freund@hitachisoftware.com>
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cc
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Doug Davis/Raleigh/IBM@IBMUS, wsrx
<ws-rx@lists.oasis-open.org>
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Subject
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[ws-rx] AnonURI and Offer and WS-Addressing
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Bob et al.
I've attached a document that outlines the flow and shows message exchanges for
a given interaction. The key question is whether the interaction:
RMD.AckRequested_EmptyBody -> EchoResponse_World_ackSeq_1_2_3
breaks the WS-Addressing spec.
Paul
Bob Freund-Hitachi wrote:
Just another log for the fire…
In reading HTTP 1.1, I do not see anything that specifies that the response entity
cannot be interpreted prior to its completion. In principle, it seems to
me that both ack and response could be sent on the same connection backchannel
provided that it was not closed prematurely. Is this how the
implementations that work do it?
Thanks
-bob
From: Doug Davis [mailto:dug@us.ibm.com]
Sent: Friday, March 10, 2006 1:36 AM
To: Paul Fremantle
Cc: wsrx
Subject: Re: [ws-rx] An alternative approach to make anon reply-to
and sync rm work
Paul,
I think there are some problems with this - I still think this violates WSA. There's
a reason anon replyTo means, in essence, the http response flow of the request
message. The connection becomes the correlator between the request and
the response - meaning if several anon requests come in the only way the server
knows which client gets which response is thru the http connection. In
your scenario if there are two anon requests sent to the server using the same
sequence and no responses sent, when the third connection is made (to carry the
ackReq) how does the server know which client is initiating the request. It
can not simply assume that just because they shared the same sequence that they
also share WSA state and that any response can be sent to any client. The
correlation is now lost.
thanks,
-Doug
The biggest issue with the two way reliable HTTP + anonURI case is the
requirement to replay request messages to get responses.
Why is this a problem? Because it means that the client has to store
requests (if and only if the interaction is two-way) beyond getting an ack
for that request.
This means that the RMS has to "know" if this particular message
interaction is one-way or two way. This means that for example, a dumb
gateway can't do it without looking at WSDLs etc.
Why do we need to do this: because WSA states:
"For instance, the SOAP 1.2
HTTP binding puts the reply message in the HTTP response."
So I agree we should not put an application reply to message A in an
HTTP response to application message B.
However, if we added the following text to our spec:
"In the case where an offered sequence is used, the RMS may send an
<wsrm:AckRequested> header together with an empty SOAP body. A valid
response to this message MAY either contain an empty SOAP body, or MAY
contain a message for the *offered* sequence".
The result of this would be that the response message on the HTTP reply
would be a valid reply to the request message and therefore would not break the
WS-Addressing text above. Effectively WSRM would be defining what
the SOAP request/reply would be, and therefore "making it right"
with respect to the HTTP binding.
So, when things are going well the HTTP reply to any given request message
would be the
correct response message. But in the case that this message got lost or
delayed, the RMS would have a choice. If it still had the message, and it
"knew" that the MEP was two-way, it could choose to resend the
original request OR it could send an empty body with an ackRequested
header.
This also gives the offered sequence a message onto which to
piggyback Close and TerminateSequence requests, solving another problem.
More importantly it removes the need for
the RMS to "know" the MEP, because by the repeated application of
empty-body ackRequests,
the RMS can get the offered sequence into a decent state.
The only compulsory implementation change I see is that the RMD would
have to be coded to know what this empty body + ackrequest means.
From the RMS I see this as optional. It is completely up to the RMS
whether it initiates a CS with Offer+AnonURI. So if an implementation doesn't
support this,
it will never initiate such a channel. And if the RMS does initiate such
a channel, it will "know" it is in this mode, that it needs to send
occasional empty ackrequests until it can close down the offered sequence.
In addition we would have to remove the words that say Offer is simply an
optimization,
because this usage makes a specific correlation between a sequence and offered
sequence.
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[attachment "AnonURI+Offer.doc" deleted by
Doug Davis/Raleigh/IBM]