Sent: Tuesday, Mar 14, 2006 1:31
To: Marc Goodner
Subject: RE: [ws-rx] AnonURI and
Offer and WS-Addressing
MG says: ...that
is a very biased characterization of the severity of the problem...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.
So, let's see, the issue should be closed with no action (I assume
because its just so obvious given what's in the spec today) but at the same
time we've been waiting for weeks for you to share some proposal with us on how
all of this is supposed to work. You crack me up.
Chris mentioned on the call last week - something is broken. WSAddr is
what it is and just because we may not like what it says for anon replyTo the
RM spec can not change it. I just don't see the latitude that you see in
the spec. Show me where it says that some other spec can change the
semantics of what WSA defines that anon replyTo means. The latitude that
I think you're referring to in the WSA spec allows other specs to define what
anon means for their own EPRs not WSAddressing's EPRs - I believe they even
added that part (in part) because of our anon AcksTo EPR issue. Whether
this is "tantamount to saying that there are fundamental flaws in
WS-A", I dunno - what I do know is that there is something flawed when
trying to use RM (as currently spec'd) with anon replyTo. Not all
features of all specs will be available when they're composed with other specs.
Anon replyTo is what it is. If someone doesn't like the semantics
that WSA defines for it then people are free to define their own URI and give
it whatever semantics they want. That's a lot of flexibility - but I can
also see the constraints it imposes.
"out only", or any other non-1-req/1-res MEP discussion, is important
because I'd like RM to be used in more than the most trivial of use-cases. You
keep not wanting to hear what I'm saying about this. The issues with
these other MEPs is that there is no mechanism for the RMS to resend messages
at will to an unreachable endpoint. You seem to focus just on the one
case of single-request/single-response and how the requestor can resend the
request to get a response resent. That's an interesting scenario but it
does nothing for the other MEPs which you seem to want to ignore. For
example, the non-RM-request/RM-response case is a very interesting one in that
there is no reason what so ever why the request would be resent and yet somehow
the response needs to somehow get retransmitted if the initial attempt fails. I'm
really hoping that this proposal you keep teasing us with will explain those
to be clear, the problems around this issue are NOT just about the new features
like Close or TerminateResponse - this unreachable endpoint problem has always
been in the RM spec and that's why it was NEVER part of any interop workshop we
held during the development of the spec. If the solution was as obvious
as you claim we would have included it.
- I'm not writing off the relevance of the unreachable client use-case. I
find it amusing that you would think,of all people, I would do that given
ws-polling's main use-case is this exact scenario. I'm just not
comfortable with violating WSA to make it happen. For a long time now I've been
advocating that WSA attack this issue but given their time constraints it
wasn't possible. So we have to live with what they've produced. If
you don't like what WSA says then I suggest you talk with your WSA folks.
03/14/2006 03:05 PM
RE: [ws-rx] AnonURI and Offer and
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
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.
Tel: (425) 703-1903
From: Doug Davis
Sent: Tuesday, March 14, 2006 10:38 AM
To: Marc Goodner
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
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
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
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.
03/14/2006 12:50 PM
RE: [ws-rx] AnonURI and Offer and
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.
Tel: (425) 703-1903
From: Doug Davis [mailto:firstname.lastname@example.org]
Sent: Monday, March 13, 2006 6:03 AM
Subject: Re: [ws-rx] AnonURI and Offer and WS-Addressing
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:
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
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
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
'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.
03/12/2006 04:43 AM
Doug Davis/Raleigh/IBM@IBMUS, wsrx
[ws-rx] AnonURI and Offer and WS-Addressing
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.
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?
From: Doug Davis [mailto:email@example.com]
Sent: Friday, March 10, 2006 1:36 AM
To: Paul Fremantle
Subject: Re: [ws-rx] An alternative approach to make anon reply-to
and sync rm work
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.
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
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
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
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
because this usage makes a specific correlation between a sequence and offered
VP/Technology, WSO2 and OASIS WS-RX TC Co-chair
"Oxygenating the Web Service Platform", www.wso2.com
VP/Technology, WSO2 and OASIS WS-RX TC Co-chair
"Oxygenating the Web Service Platform", www.wso2.com[attachment "AnonURI+Offer.doc" deleted by