RE: [ws-rx] i061 proposal / directions

Responses inline . .

"Gilbert Pilz" <Gilbert.Pilz@bea.com> wrote on 01/23/2006 06:41:27 PM:

[ stuff removed ] > Doug said:
> If an RMS uses it then it knows how to handle the http backchannel > for acks. If the RMD accepts it then it knows how to use it > too. If neither side faults on its use then I don't see the issue. > As Chris said, the RMD is always free to fault on its use and an > RMS is always free to use a non-anonymous URI. Both sides actually > have a lot of control here. My proposal simply states what both > sides can expect if it is used - if they don't like it they don't > have to use it - but at least its written down what people should > expect.
> I'm a little confused by this statement. In my mental model of this > issue, the use of the anonymous URI in the AcksTo EPR is only a > problem in cases where the AS/RMS subsequently "uses the sequence to > engage in"* message exchanges for which there is no backchannel (e. > g. one-way operations using a SOAP/HTTP implementation which does > not put SOAP envelopes in the HTTP response). If the AS/RMS uses the > sequence for messages conforming to a synchronous "send a SOAP > request over HTTP, wait for the SOAP reply in the HTTP response" > pattern there is no problem because there is a backchannel for > acknowledgements to return upon. Thus it seems unnecessarily > restrictive for an RMS to forgo all uses of the anonymous URI for > the AcksTo EPR simply because it "knows" that, in some cases, there > is no SOAP backchannel.

Who says there's no backchannel? I think that you presume that the
WS-I BP constraint that there be no SOAP envelope in the entity
body of the HTTP response message to a oneway WSDL will live to see
tomorrow? I certainly hope not. IMO, that would be a horrendous
mistake.

<gp> Whether or not WS-I BP "lives to see tomorrow" is completely besides the point. The fact is that every current specification that discusses the use of SOAP 1.1 one-way operations over HTTP specifically states that the HTTP response body must be empty. Unless each and every SOAP implementer has ignored all of these specs, this means that there are SOAP implementations out there that do not provide a backchannel for one-way operations.

>
> * Note; when I say "uses the sequence to engage in" I am implying
> that every message that carries a SOAP header with the same <wsrm:
> Identifier> is part of some logical application-level abstraction
> and that all the messages with that identifier will conform to the

Why must they conform to the same interaction pattern? That seems
unnecessarily restrictive.

<gp> Sorry, this was poor phrasing on my part. What I'm trying to say is that the RMS and RMD cannot tell ahead of time whether a particular sequence will or will not have an available backchannel since neither can tell if the application will be engaging in two-way or one-way message interactions.

> same interaction pattern. I know that this does not match your model > of independent, intermediary RMS/RMD pairs that carry all "traffic > that is to be transmitted reliably" between two clusters of services.
>
> >
> All of this still begs the question of how someone implementing an > RMS or an RMD "knows" that the use of the anonymous URI in the > AcksTo EPR might be problematic? The only thing we say about the

It knows whether IT can receive messages on the "backchannel". That's
all it needs to know. If the RMD can't handle that, it will fault on
Sequence creation.

<gp> But IT (the RMS or RMD) can't determine whether or not there will be a backchannel unless it knows two things: (a) does the underlying SOAP implementations (it's underlying SOAP implementation and the SOAP implementation of every SOAP intermediary on the path between it and it's correspond RM node) support a backchannel for one-way operations?; (b) will the application be engaging in two-way or one-way operations? I maintain that (a) is unknowable given our current technology and that, although you can make some good guesses about (b), this requires nasty things like inspecting the message which may have certain parts encrypted at the time the RM node has access to it.

> AcksTo EPR in the current spec is (lines 262-264 of wsrm-1.1-spec-cd-02) is:
> Implementations MUST NOT use an endpoint reference in the AcksTo > element that would prevent the sending of Sequence Acknowledgements > back to the RM Source. For example, using the WS-Addressing "none" > IRI would make it impossible for the RM Destination to ever send > Sequence Acknowledgements.
> The proposal listed here (http://docs.oasis-open.org/ws- > rx/issues/ReliableMessagingIssues.xml#i061) does not mention the > possibility that there may not be a SOAP backchannel for the > acknowledgements to flow back on. I'm wondering how we expect a

Can we get over this inane restriction of the WS-I BP already?

As I have said repeatedly, the use of the HTTP response flow to
carry SeqAcks is AN IMPORTANT USE CASE FOR MANY CUSTOMERS, certainly
many whom I have spoken to. Why on earth would we NOT seek to satisfy
such an important requirement? The WS-I BP MADE A MISTAKE when they
said that the HTTP response to a oneway WSDL could not carry a SOAP
envelope. It's that simple. They didn't (despite my protestations)
anticipate the advent of SOAP extensions such as WS-RM.

<gp> Just to be clear, I am 100% behind using the HTTP response flow to carry acknowledgements. All I'm saying is that there may be cases where the only way this will work is if the application forgoes the use of asynchronous communications. I don't care if WS-I BP made a mistake. BP 1.0 and BP 1.1 are both out there and there are no specifications that contradict them on this matter. Whether they are right or wrong is completely irrelevant. Specifications do not exist in a vacuum. We have to take into account the current state of affairs with regards to SOAP implementations. Insisting that WS-RM will only work with SOAP implementations that have ignored all the specifications on the use of one-way SOAP/HTTP operations is irresponsible. I don't think anybody's customers would be pleased to hear that may or may not have to upgrade some or all of their SOAP stacks if they want to use WS-RM.

> developer to know precisely when and where the use of the anonymous
> URI in the AcksTo EPR might be problematic when our spec says
> nothing about the subject?
>
> - g
>

ws-rx message