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Re: [ws-rx] Re: Comment on WSDL spec: use of Anonymous Element

From: Christopher B Ferris <chrisfer@us.ibm.com>
Date: Wed, 9 Aug 2006 08:45:13 -0500
To: Alastair Green <alastair.green@choreology.com>
Cc: public-ws-addressing@w3.org, public-ws-addressing-request@w3.org, ws-rx@lists.oasis-open.org
Message-ID: <OF7E2D1790.D0672DBF-ON852571C5.004988E3-852571C5.004B850C@us.ibm.com>
Alistair,

> If you say there is no reply, then you are saying: don't send a 
> response.

Again, the SOAP-level is distinct from the transfer/transport-level. They 
are NOT at all related.
It is only that many assume that they are, when in fact, they are not.

Cheers,

Christopher Ferris
STSM, Software Group Standards Strategy
email: chrisfer@us.ibm.com
blog: http://www.ibm.com/developerworks/blogs/dw_blog.jspa?blog=440
phone: +1 508 377 9295

Alastair Green <alastair.green@choreology.com> wrote on 08/08/2006 
11:42:10 AM:

> Chris,
> 
> Redoing part of WS-A in RM creates difficulty in WS-A WSDL (start of
> thread). Raises question: Why won't standard WS-A anon facility work?
> 
> You have to say something about where you reply to. If you want the 
> reply to come on the back-channel then WS-A has a way of saying that
> (and you get that by default).
> 
> If you say there is no reply, then you are saying: don't send a 
> response. But MC precisely invites a response. How is a WS-A 
> implementation supposed to understand (without being RM aware) that 
> reply=none really means (functionally) reply=anon? I perceive 
> unnecessary layering tangle. WS-A layer now expected to hold HTTP 
> response for app, even though told that there is no response.
> 
> Researching further, I don't understand why an RM-specific 
> alternative to reply=anon has been introduced for the "address" 
> case, but not for the "sequence" case. 
> 
> I believe regular "use back channel" feature of WS-A can be used, 
> and the RM layer can handle RM "sessions", in both cases.
> 
> Does my example of sequence case indicate expected behaviour? Would 
> it be wrong to say MC/reply=anon with sequence case?
> 
> First part of long message addresses Doug's points about the 
> application-level set-up message: I don't understand the relevance 
> of that type of message.
> 
> Alastair
> 
> 
> 
> Christopher B Ferris wrote: 
> 
> Alastair, 
> 
> Is this a long and drawn out manner of stating that when a message 
> is a true oneway (e.g. no 
> response is expected) then the wsa:ReplyTo should be the WS-A none 
> URI rather than 
> simply leaving it absent and hence falling trap to the "if not 
> present, default to anon" gotcha? 
> 
> I guess I am not seeing an issue here, although I guess it would be 
> fine if we recommended or required 
> that the MakeConnection wsa:ReplyTo MAP carry the WS-A none URI. 
> 
> Cheers, 
> 
> Christopher Ferris
> STSM, Software Group Standards Strategy
> email: chrisfer@us.ibm.com
> blog: http://www.ibm.com/developerworks/blogs/dw_blog.jspa?blog=440
> phone: +1 508 377 9295 
> 
> public-ws-addressing-request@w3.org wrote on 08/08/2006 07:06:32 AM:
> 
> > Doug, Paul --
> > 
> > I'm going to try to address both your comments. if I can summarize 
> > Paul's it was: what's the big deal about [reply endpoint] when 
> > MakeConnection is "one-way"?. 
> > 
> > Given RX timescales you may want to treat these remarks as "early 
> > public review".
> > 
> > * * *
> > 
> > Doug's message 1 is an application-level set-up call which 
> > establishes common understanding of the UUID. This type of message 
> > is exemplified by that shown in the CD example Step 1, unless I have
> > completely misunderstood.
> > 
> > In that example, a subscriber, who cannot listen, sends a subscribe 
> > message to a publisher, saying something like "subscribe me for 
> > topics A, B, C. The identity of this subscription request is UUID 
> > X". Thereafter, the publisher knows that X equals "subscription for 
> > topics A, B, C".
> > 
> > Assertion 1 (please correct me if I am wrong): The format, content 
> > etc of this type of message (and its manner of transmission) are 
> > entirely application-specific. It may or may not require an 
> > acknowledgement. It could be sent by carrier pigeon, or by fax. The 
> > subscribe message, if sent as SOAP-with-Addressing, might receive a 
> > reply, or might not receive a reply, and if it did, it might receive
> > it anon or addressable. There are no RM rules that apply to this 
> > message. There are only application rules. It cannot do its job 
> > usefully unless it passes the UUID: that is all we can say.
> > 
> > Assertion 2. At present there is an RM rule which says: "the 
> > mutually understood UUID must be reflected in the [destination 
> > endpoint] according to an RM URI scheme". There are no RM rules to 
> > say whether the connection UUID, during the course of establishing 
> > mutual understanding, travels alone, embedded in a URI, in a body 
> > element or a header element. These are all matters of bilateral 
> > agreement at an app level between (in this case) the 
> > consumer/subscriber and the producer/publisher.
> > 
> > [The example is potentially a bit misleading in this respect. 
> > 
> > The use of the full "anon-URI?id={uuid}" value in the <targetEPR/>, 
> > and the use of the element name "targetEPR" make one think 
> > "addressing", when one would be better off thinking "subscription 
> > identity" (at an app level). The example set-up message would work 
> > perfectly well if it read:
> > 
> > <S:Body>
> >     <!-- subscription details --> 
> >     <SubscriptionIdentity>{uuid}</SubscriptionIdentity>
> > </S:Body>
> > 
> > Btw, given that the use of MakeConnection requires a prior 
> > understanding between two parties of the connection identity, there 
> > seems no reason why {uuid} has to be a UUID. It does need to be 
> > bilaterally unambiguous.]
> > 
> > * * *
> > 
> > Message 2 is MakeConnection. If the subscriber sends a 
> > MakeConnection, specifying UUID X, then the publisher knows it is 
> > dealing with traffic relating to subscription X, i.e. for topics A, 
> > B and C. At an application level, we assume that the contract 
> > thereafter is: start reliably communicating a stream of messages, 
> > relating to topics A, B and C, therefore implying sequence creation 
> > etc, until something causes the stream to close. 
> > 
> > So the subscriber will repeatedly send MakeConnection, citing the 
> > UUID X, read the HTTP response, and handle the response as if it 
> > were an inbound RM/RM-app message.
> > 
> > The exchange that RM defines (rather than illustrates) is the 
> > MakeConnection, back-call-on-the-connection one. It's this exchange 
> > that I am discussing. MakeConnection is the message affected by the 
> > WSAW anon=required discussion, as I see it.
> > 
> > [While it is probably helpful for diagnostic reasons to repeat the 
> > UUID back to the sender of MakeConnection in the [destination 
> > endpoint], it is actually redundant, as the HTTP Response is 
> > automatically and uniquely correlated with the HTTP Request. This 
> > might lead one to the conclusion that the simple solution would have
> > been: send UUID on MakeConnection, and then respond to it on the 
> > anonymous back-channel without reflection of UUID in any form 
> > However, this would reduce the symmetry with the Sequence identified
> > use of MakeConnection, see comments later]
> > 
> > * * *
> > 
> > There are two modes in which this exchange can work (reflecting the 
> > joint proposal, as I understand it):
> > 
> > a) Send response as part of a sequence that already exists
> > b) Use response to create a new sequence, etc
> > 
> > This is relevant to answering Paul F's question, relating to the 
> > significance of ReplyTo.
> > 
> > If there is a sequence, then the sequence Identifier is a 
> > correlation synonym for the UUID. The reply message may be sent on 
> > the back-channel; it must carry the wsrm:Identifier (as a separate 
> > header element), it need not carry the UUID.
> > 
> > If there is no sequence, then the reply message must carry or imply 
> > the UUID. (I'm going to assume that carrying the UUID is better than
> > implying it.) The question is how?
> > 
> > Looking at these two cases, it is striking that both 
> > 
> > a) require a response on the back-channel,
> > b) need to carry an identifier (one of the sequence, one of the 
> > "connection"/"session")
> > 
> > Doug's comment that there is no wsa:ReplyTo on the MakeConnection, 
> > that it is "one way", is relevant here. In fact there is no such 
> > thing (in the XML infoset) as a non-existent [reply endpoint]. If 
> > wsa:ReplyTo is absent, then it is inferred to be the anon-URI. The 
> > only way you can stop that inference is to set the [reply endpoint] 
> > to none or to a "real address". I don't think you want to do either 
> > of those things, in this context.
> > 
> > With these points in mind, I think it is worth looking again at my 
> > previous postings. 
> > 
> > The orthodox way of saying "respond on the back-channel" is setting 
> > [reply endpoint] to anon. This can be done explicitly or by 
> > inference from absence.
> > 
> > I think there has to be a good reason to invent a new way of 
> > expressing this semantic. Doing so has repercussions (see the 
> > original starting point of this thread, re WSA W anon/required). The
> > (very valuable) use case of MakeConnection does not require an 
> > alternate mechnanism for stating the back channel semantic. 
> > 
> > We can illustrate all of this by placing three examples side by side:
> > 
> > * * *
> > 
> > 1. Example using sequence Identifier: MakeConnection and reply [asper 
CD 04]
> > 2. Example using hypothetical connection identifier: MakeConnection 
> > and reply [as it could be, simplified]
> > 3. Example using current Address [as per CD 04]
> > 
> > 1a. Example using sequence Identifier: MakeConnection
> > 
> > <S:Envelope xmlns:S="http://www.w3.org/2003/05/soap-envelope"
> >             xmlns:wsrm="http://docs.oasis-open.org/ws-rx/wsrm/200608"
> >             xmlns:wsa="http://www.w3.org/2005/08/addressing">
> >     <S:Header>
> >         <wsa:MessageID>http://example.org/subscriptionService/
> > guid/61e0654e-5ce8-477b-bb9d-34f05cdcbc9e</wsa:MessageID>
> >         <wsa:Action>http://docs.oasis-open.
> org/wsrx/wsrm/200608/MakeConnection
> > </wsa:Action>
> >         <wsa:To>http://example.org/subscriptionService</wsa:To>
> > <!-- absent wsa:ReplyTo is equivalent to: 
> >         <wsa:ReplyTo>
> >             <wsa:Address>http://docs.oasis-open.
> org/wsrx/wsrm/200608/anonymous
> > </wsa:Address>
> >         </wsa:ReplyTo>
> > -->
> >     </S:Header>
> >     <S:Body>
> >         <wsrm:MakeConnection> 
> >             <wsrm:Identifier>http://Business456.
> > com/SubscribeTopics/Sequence/7456-3278</wsrm:Identifier>
> >         </wsrm:MakeConnection> 
> >     </S:Body>
> > </S:Envelope>
> > 
> > 1b. Example using sequence Identifier: reply to MakeConnection
> > 
> > <S:Envelope xmlns:S="http://www.w3.org/2003/05/soap-envelope"
> >             xmlns:wsrm="http://docs.oasis-open.org/ws-rx/wsrm/200608"
> >             xmlns:wsa="http://www.w3.org/2005/08/addressing">
> >     <S:Header>
> >         <wsa:MessageID>http://example.org/subscriptionService/
> > guid/71e0654e-5ce8-477b-bb9d-34f05cfcbc9e</wsa:MessageID>
> >         <wsa:RelatesTo>http://example.org/subscriptionService/
> > guid/61e0654e-5ce8-477b-bb9d-34f05cdcbc9e</wsa:RelatesTo>
> > <wsa:ReplyTo><wsa:Address>http://example.org/subscriptionService
> > </wsa:Address></wsa:ReplyTo>
> >         <wsa:Action>http://example.com/subscriptionService/publish
> > </wsa:Action>
> >         <wsrm:Sequence>
> >             <wsrm:Identifier>http://Business456.
> > com/SubscribeTopics/Sequence/7456-3278</wsrm:Identifier>
> >             <wsrm:MessageNumber>1</wsrm:MessageNumber>
> >         </wsrm:Sequence>
> >     </S:Header>
> >     <S:Body>
> >         <!-- Publication re A, B or C -->
> >     </S:Body>
> > </S:Envelope>
> > 
> > 2a. Example using hypothetical connection identifier: MakeConnection
> > 
> > <S:Envelope xmlns:S="http://www.w3.org/2003/05/soap-envelope"
> >             xmlns:wsrm="http://docs.oasis-open.org/ws-rx/wsrm/200608"
> >             xmlns:wsa="http://www.w3.org/2005/08/addressing">
> >     <S:Header>
> >         <wsa:MessageID>http://example.org/subscriptionService/
> > guid/61e0654e-5ce8-477b-bb9d-34f05cdcbc9e</wsa:MessageID>
> >         <wsa:Action>http://docs.oasis-open.
> org/wsrx/wsrm/200608/MakeConnection
> > </wsa:Action>
> >         <wsa:To>http://example.org/subscriptionService</wsa:To>
> > <!-- absent wsa:ReplyTo is equivalent to: 
> >         <wsa:ReplyTo>
> >             <wsa:Address>http://docs.oasis-open.
> org/wsrx/wsrm/200608/anonymous
> > </wsa:Address>
> >         </wsa:ReplyTo>
> > -->
> >     </S:Header>
> >     <S:Body>
> >         <wsrm:MakeConnection> 
> >             <wsrm:ConnectionIdentifier>http://Business456.com/
> > SubscribeTopics/Stream/7457</wsrm:ConnectionIdentifier>
> >         </wsrm:MakeConnection> 
> >     </S:Body>
> > </S:Envelope>
> > 
> > 2b. Example using hypothetical connection identifier: reply to 
> > MakeConnection (CreateSequence)
> > 
> > <S:Envelope xmlns:S="http://www.w3.org/2003/05/soap-envelope"
> >             xmlns:wsrm="http://docs.oasis-open.org/ws-rx/wsrm/200608"
> >             xmlns:wsa="http://www.w3.org/2005/08/addressing">
> >     <S:Header>
> >         <wsa:MessageID>http://example.org/subscriptionService/
> > guid/71e0654e-5ce8-477b-bb9d-34f05cfcbc9e</wsa:MessageID>
> >         <wsa:RelatesTo>http://example.org/subscriptionService/
> > guid/61e0654e-5ce8-477b-bb9d-34f05cdcbc9e</wsa:RelatesTo>
> >         <wsa:Action>http://docs.oasis-open-
> org/wsrx/wsrm/200608/CreateSequence
> > </wsa:Action>
> > <wsa:ReplyTo>http://example.org/subscriptionService</wsa:ReplyTo>
> >         <wsrm:ConnectionIdentifier>
> >             http://Business456.com/SubscribeTopics/Stream/7457
> >         </wsrm:ConnectionIdentifier> 
> >     </S:Header>
> >     <S:Body>
> >         <wsrm:CreateSequence>
> >             <wsrm:AcksTo>
> >                 <wsa:Address>http://example.org/subscriptionService
> > </wsa:Address>
> >             </wsrm:AcksTo>
> >         </wsrm:CreateSequence>
> >     </S:Body>
> > </S:Envelope>
> > 
> > 3a. Example using wsrm:Address: MakeConnection
> > 
> > <S:Envelope xmlns:S="http://www.w3.org/2003/05/soap-envelope"
> >             xmlns:wsrm="http://docs.oasis-open.org/ws-rx/wsrm/200608"
> >             xmlns:wsa="http://www.w3.org/2005/08/addressing">
> >     <S:Header>
> >         <wsa:MessageID>http://example.org/subscriptionService/
> > guid/61e0654e-5ce8-477b-bb9d-34f05cdcbc9e</wsa:MessageID>
> >         <wsa:Action>http://docs.oasis-open.
> org/wsrx/wsrm/200608/MakeConnection
> > </wsa:Action>
> >         <wsa:To>http://example.org/subscriptionService</wsa:To>
> > <!-- absent wsa:ReplyTo is equivalent to: 
> >         <wsa:ReplyTo>
> >             <wsa:Address>http://docs.oasis-open.
> org/wsrx/wsrm/200608/anonymous
> > </wsa:Address>
> >         </wsa:ReplyTo>
> > -->
> >     </S:Header>
> >     <S:Body>
> >         <wsrm:MakeConnection> 
> >             <wsrm:Address>
> >                 http://docs.oasis-open.
> > org/wsrx/wsrm/200608/anonymous?id=550e8400-e29b-11d4-a716-446655440000
> >             </wsrm:Address>
> >         </wsrm:MakeConnection> 
> >     </S:Body>
> > </S:Envelope>
> > 
> > 3b. Example using wsrm:Address: reply to MakeConnection 
(CreateSequence)
> > 
> > <S:Envelope xmlns:S="http://www.w3.org/2003/05/soap-envelope"
> >             xmlns:wsrm="http://docs.oasis-open.org/ws-rx/wsrm/200608"
> >             xmlns:wsa="http://www.w3.org/2005/08/addressing">
> >     <S:Header>
> >         <wsa:MessageID>http://example.org/subscriptionService/
> > guid/71e0654e-5ce8-477b-bb9d-34f05cfcbc9e</wsa:MessageID>
> >         <wsa:RelatesTo>http://example.org/subscriptionService/
> > guid/61e0654e-5ce8-477b-bb9d-34f05cdcbc9e</wsa:RelatesTo>
> >         <wsa:Action>http://docs.oasis-open-
> org/wsrx/wsrm/200608/CreateSequence
> > </wsa:Action>
> >         <wsa:To>
> > 
> > <!-- I believe this is WS-A illegal: reply To must equal request 
> > ReplyTo/Address. --> 
> > 
> >             http://docs.oasis-open.org/wsrx/wsrm/200608/anonymous?
> > id=550e8400-e29b-11d4-a716-446655440000
> >         </wsa:To>
> > <wsa:ReplyTo>http://example.org/subscriptionService</wsa:ReplyTo>
> >     </S:Header>
> >     <S:Body>
> >         <wsrm:CreateSequence>
> >             <wsrm:AcksTo>
> >                 <wsa:Address>http://example.org/subscriptionService
> > </wsa:Address>
> >             </wsrm:AcksTo>
> >         </wsrm:CreateSequence>
> >     </S:Body>
> > </S:Envelope>
> > 
> > Yours,
> > 
> > Alastair
> > 
> > Doug Davis wrote: 
> > 
> > Alastair, 
> >   I think you're mixing up the messages a bit.  There are two messages 

> > at play: 
> > 1 - the message containing the EPR to send subsequent messages to. 
> >     In some cases this message will have the EPR in its wsa:ReplyTo 
> >     header, but it could also be placed someplace else depending 
> >     on its use.  And it is this EPR that needs to be tagged as the 
> >     polling one (ie. it has the RM anon URI). 
> >     This message will contain application specific data in the Body 
> >     so your suggestion of placing some UUID in there will not work. 
> >     This gets back to the necessity to keep all info about where to 
> >     send messages encapsulated into whatever EPR we want to be tagged 
> >     as the polling one. 
> > 
> > 2 - the MakeConnection message. 
> >     This message does not have a wsa:ReplyTo, its a one-way.  This 
> >     message does contain a Body which is the correlation info used 
> >     by the receiver of this message to find an appropriate message 
> >     to send back.  So, basically the stuff in the Body must match 
> >     the EPR from message 1.  And given that in some cases the only 
> >     thing remaining from the EPR in message 1 is the serialized 
> >     version of it, we must be able to find messages based solely 
> >     on what's in the outgoing message itself.  Which means the 
> >     wsa:To field.  Again, ref-p's are bad for this purpose. :-) 
> > 
> > HTH 
> > 
> > thanks 
> > -Doug 
> > 
> > 
> > 
> > Alastair Green <alastair.green@choreology.com> wrote on 08/07/2006 
> > 02:02:55 PM:
> > 
> > > Doug,
> > > 
> > > I think I'm connecting, if you'll pardon the pun. 
> > > 
> > > 1. As I read WS-A, the [destination endpoint][address] must be set 
> > > to [reply endpoint][address] for a reply.
> > > 
> > > 2. If [reply endpoint] is omitted (as per the CD example), then 
> > > [reply endpoint] = anon, by default.
> > > 
> > > 3. If [destination endpoint] = "anon-URI?id={uuid}", then 
> > > [destination endpoint] <> [reply endpoint][address] (which was 
> > > simple, unornamented anon-URI), which contradicts premise 1.
> > > 
> > > Does that make sense? If so, then I think you would need to set 
> > > [reply endpoint] to none, explicitly, to avoid that clash (given 
> > > RM's current approach). But this causes
> > > 
> > > 4. The WS-A processor that sent MakeConnection to get very confused.
> > > It wasn't expecting anything but an HTTP 200 series by way of a 
> > > response, but is about to get a full-scale SOAP message bounding 
back.
> > > 
> > > +++
> > > 
> > > Further thoughts, which continue, in my mind, to question the 
> > > current RM approach, but which may ease the WSA W problem.
> > > 
> > > a) You could have defined an extension element in the [reply 
> > > endpoint] for the UUID.
> > > 
> > > b) Or, you could have chosen to send the UUID in the body element.
> > > 
> > > c) In either case, this could team up with setting [reply 
> > endpoint] to anon. 
> > > 
> > > d) As in 3. above, you shouldn't then set response [destination 
> > > endpoint] to anon?id={uuid}.
> > > 
> > > e) So, you need to set [reply endpoint] to anon, and set 
> > > [destination endpoint][address] to anon.
> > > 
> > > f) which begs the question, where does the UUID go?
> > > 
> > > g)  If you passed an extension element UUID, or a UUID in the body 
> > > element, and then passed it back as an extension element in the anon
> > > EPR that should be OK, because you have followed the rules for reply
> > > formulation with respect to the [destination endpoint][address]
> > > /[reference parameters]. The fact you have chosen to put an 
> > > extension element in the response is WS-A 3.3/3.4 legal, as I read 
> > > it. That's a higher-layer behaviour that does not contradict WS-A 
> > > base behaviour, which is constrained.
> > > 
> > > +++
> > > 
> > > Why is g) not viable in your view? The processors that need to 
> > > understand the body/extension UUID element are the RM senders and 
> > > responders (not the WS-A processors, which passively pass on the 
> > > UUID to the RM receiver of MakeConnection, and pass on the extension
> > > element to the RM receiver of the response). 
> > > 
> > > In other words, the awareness of RM-ness that is demanded in 
> > > formulating MakeConnection, and in replying to it, resides in the 
> > > same place, and at the same level, as in the current (CD) solution.
> > > 
> > > The difference being: that the MakeConnection is now a regular 
> > > [reply endpoint] = anon. At which point special WSAW rules are not 
needed.
> > > 
> > > I don't see any lesser or greater problem with intermediaries, 
> > > onward transmission etc than would apply with the current solution, 
> > > if that is a concern. On this point, I think I may be missing 
> > > something, or misunderstanding your area of concern?
> > > 
> > > So, to summarize:
> > > 
> > > 1. asimple-non out, special, ornamented-anon back is a problem.
> > > 2. none out, anon back is a problem.
> > > 3. extension element UUID out, extension element UUID back, is no 
> > > different, in layer terms, than body UUID out, ornamented address 
> > > back, i.e. is not a problem.
> > > 4. anon out means no problem with anon = required.
> > > 
> > > 
> > > * * *
> > > 
> > > My last point was indeed completely beside the point of your issue :
> > > -) -- it is an independent issue about WSAW, and a limitation that 
> > > the proposed syntax seems to impose by applying the flag across all 
> > > "response endpoints". 
> > > 
> > > Alastair
> > > 
> > > Doug Davis wrote: 
> > > 
> > > Alastair, 
> > >   We did consider adding some extra metadata to the EPR (outside of 
> > > the wsa:Address and ref-p's), but there's a problem - this metadata 
> > > is not copied over into the response message - just the wsa:Address 
> > > and ref-p's are.  This means that any data placed elsewhere in the 
> > > EPR is lost once the message is serialized.  So unless we assume the
> > > impl can hold on to the original EPR for the entire message path 
> > > (which we can't in distributed systems), the identity part must be 
> > > in either the address or ref-p's.  And, as you said, ref-p's aren't 
> > > good for this. 
> > > 
> > >   What's interesting about your anon?unique-id example is that that 
> > > solution might work very nicely (we talked about this in the past) -
> > > but as you said it would require WSA to say anon URIs 'start 
> > > with...' - and WSA is closed :-( 
> > > 
> > >   I got a bit lost on your last point - it almost sounded like a 
> > > complaint about the current WSA WSDL spec instead of my issue -  or 
> > > did I not follow it? 
> > > 
> > >   I noticed that on the agenda for tomorrow's WSA call (I think its 
> > > tomorrow) is a CR issue that mentioned how this wording in the WSDL 
> > > spec prevents the use of "none".  I can't help but think that both 
> > > issues (mine and the other CR issue) would be solved nicely if the 
> > > wording were turned around a bit and said something about how this 
> > > flag indicates whether or not the endpoint supports addressable 
> > > endpoints in the response EPRs.  Not sure of the exact wording, but 
> > > if instead of taking about specific URIs (like anon and none) it 
> > > talked about whether the endpoint supported the notion of creating 
> > > it own connections to the EPR then it wouldn't need to get into the 
> > > business of listing all of the URIs that are valid.  And I think it 
> > > would relay the exact same information. 
> > > 
> > > thanks 
> > > -Doug 
> > > 
> > > 
> > 
> > > 
> > > Alastair Green <alastair.green@choreology.com> 
> > > 08/04/2006 10:57 AM 
> > > 
> > > To 
> > > 
> > > Doug Davis/Raleigh/IBM@IBMUS 
> > > 
> > > cc 
> > > 
> > > public-ws-addressing@w3.org, public-ws-addressing-request@w3.org, 
> > > ws-rx@lists.oasis-open.org, abbieb@nortel.com, aclark@novell.com, 
> > > akira.tanaka.pr@hitachi.com, aleyfer@actional.com, 
anash@reactivity.com, 
> > > andreas.bjarlestam@ericsson.com, anil.edakkunni@soa.com, anil.
> > john@jhuapl.edu
> > > , Anish.Karmarkar@oracle.com, Anthony Nadalin/Austin/IBM@IBMUS, 
> > > asakala@iona.com, ash@rainingdata.com, ashok.malhotra@oracle.com, 
> > > asirveda@microsoft.com, atarashi@sv.nec-labs.com, atmanes@gmail.com, 

> > > audet@nortel.com, barreto@adobe.com, bhakti.mehta@sun.com, blake.
> > > dournaee@intel.com, bob.freund@hitachisoftware.com, 
bob.sunday@pwgsc.gc.ca
> , 
> > > b.eckenfels@seeburger.de, carolina.canales@ericsson.com, 
> chamikara@wso2.com
> > , 
> > > chappell@sonicsoftware.com, Charles Levay/Raleigh/IBM@IBMUS, 
> > > chouthri@sv.nec-labs.com, Christopher B Ferris/Waltham/IBM@IBMUS, 
> > > Christopher.Kurt@microsoft.com, chris.hipson@bt.com, "'von 
> Riegen, Claus'" 
> > > <claus.von.riegen@sap.com>, coevans@microsoft.com, 
> cunningham_david@bah.com
> > , 
> > > dan@actional.com, "'Burdett, David'" <david.burdett@sap.com>, 
> > > dconnelly@openapplications.org, Diane Jordan/Raleigh/IBM@IBMUS, 
> > > dkmin@konkuk.ac.kr, dleshc@tibco.com, dmoberg@us.axway.com, 
> > dnickull@adobe.com
> > > , "'David Orchard'" <dorchard@bea.com>, doug.bunting@sun.com, 
> > > eisaku.nishiyama.dd@hitachi.com, email@cbvenkat.net, 
eoghan.glynn@iona.com
> , 
> > > Eric.Newcomer@iona.com, eric.rajkovic@oracle.com, eric.
> > > wells@hitachisoftware.com, ganga.sah@oracle.com, gatfora@uk.ibm.com, 

> > > gboschi@sonicsoftware.com, gdaniels@sonicsoftware.com, "'Gilbert 
Pilz'" 
> > > <Gilbert.Pilz@bea.com>, girish.juneja@intel.com, 
gregcarp@microsoft.com, 
> > > greg.pavlik@oracle.com, hbenmalek@us.fujitsu.com, 
heiko.braun@jboss.com, 
> > > ian.c.jones@bt.com, ian_robinson@uk.ibm.com, 
james.speer@capgemini.com, 
> > > jamie.clark@oasis-open.org, jdurand@us.fujitsu.com, jeff.
> > > mischkinsky@oracle.com, jekanaya@cs.indiana.edu, 
Jiri.Tejkl@systinet.com, 
> > > jjchoe@tmax.co.kr, jkchoi@methodi.com, jmarsh@microsoft.com, joeri.
> > > van_cleynenbreugel@alcatel.be, john.gotze@oasis-open.org, john.
> > kemp@nokia.com
> > > , joseph.2.waller@bt.com, junghc@nca.or.kr, jypyon@nca.or.kr, k-
> > > seki@da.jp.nec.com, kcyee@cecid.hku.hk, kiwasa@jp.fujitsu.com, 
> > > lburch@novell.com, lily.liu@webmethods.com, "'Lei Jin'" 
<ljin@bea.com>, 
> > > machi@nca.or.kr, "'Mark Little'" <mark.little@jboss.com>, 
> > > "'Schenecker, Mark'" <mark.schenecker@sap.com>, "'de Boer, Martijn'" 

> > > <martijn.de.boer@sap.com>, "'Raepple, Martin'" 
<martin.raepple@sap.com>, 
> > > mary.mcrae@oasis-open.org, matsuki.yoshino.pw@hitachi.com, 
> > mckierna@uk.ibm.com
> > > , mgoodner@microsoft.com, mhb@itst.dk, "'Bechauf, Michael'" 
> > > <michael.bechauf@sap.com>, mike.grogan@sun.com, millwood@uk.ibm.com, 

> > > mlovett@uk.ibm.com, mlyons@layer7tech.com, mschenecker@e2open.com, 
> > > mwang@tibco.com, nickr@enosis.com, nilo.mitra@ericsson.com, 
> > > nobuyuki.yamamoto.vw@hitachi.com, Ondrej.Hrebicek@microsoft.com, 
> > paul@wso2.com
> > > , pauld@mitre.org, paul.cotton@microsoft.com, 
paul.knight@nortel.com, 
> > > peter.furniss@erebor.co.uk, peter_niblett@uk.ibm.com, 
pete.wenzel@sun.com
> , 
> > > prateek.mishra@oracle.com, pyendluri@webmethods.com, Richard 
> > > Salz/Cambridge/IBM@IBMUS, robin@oasis-open.org, sada@jp.fujitsu.com,
> > > "'Patil, Sanjay'" <sanjay.patil@sap.com>, sanka@wso2.com, 
> scayron@acord.org
> > > , Scott Hinkelman/Austin/IBM@IBMUS, shengsong.ni@oracle.com, 
> > > shivajee@tibco.com, srcarter@novell.com, stefanba@microsoft.com, 
> > > "'Rossmanith, Stefan'" <stefan.rossmanith@sap.com>, "'Winkler, 
Steve'" 
> > > <steve.winkler@sap.com>, sumit.gupta@oracle.com, 
tboubez@layer7tech.com, 
> > > tejeswar.das@iona.com, thomas.erl@soasystems.com, 
thomas.t.bui@boeing.com
> , 
> > > timothy@drummondgroup.com, toby.considine@unc.edu, tom@coastin.com, 
> > > "'Yalcinalp, Umit'" <umit.yalcinalp@sap.com>, vfurman@webmethods.com
> > > , "'Shipkowitz, Vicki'" <vicki.shipkowitz@sap.com>, 
vikas@sonoasystems.com
> > > , "'Videlov, Vladimir'" <vladimir.videlov@sap.com>, Martin Chapman 
> > > <martin.chapman@oracle.com> 
> > > 
> > > Subject 
> > > 
> > > Re: Comment on WSDL spec: use of Anonymous Element 
> > > 
> > > 
> > > 
> > > 
> > > Hi Doug,
> > > 
> > > Comments interspersed:
> > > 
> > > Doug Davis wrote: 
> > > 
> > > Alastair, 
> > >  There are a couple of different things at play here. First, sorry 
> > > about the long cc-list but the wsrx mailing list still doesn't 
> > > appear to work so I need to include the entire wsrx team manually 
:-( 
> > > I thought my mail client was going to expire when I just did "reply 
all". 
> > > 
> > > In a non-anonymous world the wsa:Address field represents both the 
> > > fact that the destination can access connections and it identifies 
> > > the party.  And I think that makes sense.  There is no reason to not
> > > have a single URI do that (let's not get into the 'identity' issue 
> > > w.r.t. ref-p's  :-).   So, if we then switch over to the anonymous 
> > > case, IMO, I don't believe the implementation should need to change 
> > > w.r.t. the purpose of this URI. 
> > > Here's what I don't understand. In the non-anon case an EPR (address
> > > + stuff) is used to target. In the anon case, so far as I can tell, 
> > > there is nothing in WS-A to stop the same "full EPR" (address + 
> > > stuff) being used to target the reply.
> > > 
> > > If one pursues this, what you intuitively want is: callback EPR = 
> > > {address = anon URI, ref-param[0] = identity}.
> > > 
> > > But ref-params are opaque. Not what you want. (Although I can't see 
> > > how to stop an app contract, e.g. RM, specifying that we'll use a 
> > > mutually-known type for a ref-param, and make its presence mandatory
> > > for certain messages). 
> > > 
> > > Assume that ref-param is not good. Why not add an RM extension 
> > > element to the EPR? This retains the identity lexeme within the EPR.
> > > A WS-A impl should be happy to insert and extract such extension 
> > > elements, even if it hasn't a clue what they mean. 
> > > 
> > > In the simple WS-Addr anon use-case the URI still indicates both 
> > > things - whether or not (and 'not' in this case) the destination 
> > > will accept a connection, and it also indicates the identity - sort 
> > > of.  The identity is implicitly defined by the fact that it is tied 
> > > to the connection on which the request came in on.  If we did what 
> > > you're suggesting and add a second header then, IMO, RM would 
> > > require quite a big change to people's soap processor.  I think WS-
> > > Addr did a really good thing by keeping everything people need to 
> > > know with a single structure - the EPR.  Even with the introduction 
> > > of the anonymous URI (which could very easily have been introduced 
> > > in a much less cleaner fashion), most of the SOAP processor doesn't 
> > > really need to know what the specific value of the wsa:Address 
> > > element is until it tries to actually send the message over the 
wire. 
> > >  So, if we then switch over the MakeConnection use-case, I think RM 
> > > did the right thing by using the same mechanism WS-Addr did - keep 
> > > everything within a single EPR. 
> > > OK, but I think you may be conflating "a single EPR" with "the 
> > > address element of a single EPR".
> > > 
> > > This allows for most of the SOAP processor to be totally unaware of 
> > > the actually transport mechanism until (or close to) the time the 
> > > message is serialized on the wire.  If there were additional headers
> > > to carry this information then existing WS-Addr logic of mapping a 
> > > wsa:ReplyTo over to a wsa:To + ref-p headers when constructing a 
> > > response might need to also change.  There's also lots of other use-
> > > cases where the logic to handle the RM code isn't on the same 
> > > machine doing this WS-Addr mapping so if its not aware of RM at all 
> > > it wouldn't even know to include some special bit on the outgoing 
> > > message (either in the message or in the soap processor's metadata 
> > > about the message) to indicate that MakeConnection will be used. 
> > > Things are just a whole lot easier if everything is encapsulated in 
> > > a single EPR, and more specifically in the wsa:Address field.  Which
> > > is exactly how WS-Addr anon works today. 
> > > Hmm, back to the conflation. I can't see anything in the WS-Addr 
> > > spec that prevents use of ref params, metadata or extensibility 
> > > elements within an anon EPR.  Here, you want to use the special 
> > > value of [address], and put an application-defined type/value in the
> > > rest of the EPR. That would fit your requirement to "keep it in the 
EPR". 
> > >   I don't think loosening the wording makes thing indeterminate - it
> > > still requires a URI with the proper semantics, but it allows for 
> > > the composition of other specifications that may defined their own. 
> > > And, IMO, as long as they are consistent with WS-Addr's definition 
> > > of anon, from a WS-Addr perspective, then how they choose to add 
> > > additional semantics is up to them. 
> > > I'm not convinced. I think you are layer-violating -- introducing 
> > > precisely the problem that you are trying to avoid. 
> > > 
> > > At the SOAP processing level this message is full of arcane headers 
> > > of unknown meaning. At the WS-A processor level, these are 
> > > commonplace headers with well-defined meanings, which may contain 
> > > some arcane app ref params and extension elements of unknown 
meaning. 
> > > 
> > > [reply endpoint][address] = anon URI means: "send a response on the 
> > > back-channel". At the last minute the WS-A processor whacks the 
> > > arcana (ref-params, metadata and extensibility elements) into the 
> > > header and whisks them off on the response. Receiving WS-A processor
> > > gives the arcana to the app, for which they are meaningful (for 
> > > routing or correlation or whatever).
> > > 
> > > This works because the WS-A receiver can look at well-known, 
> > > expected endpoint [reply endpoint] and can find the well-known, 
> > > expected anon URI -- and need think no further. Anon URI = use 
> > back channel. 
> > > 
> > > If the URI is different (anon-URI?tum-ti-tum-ti-tum) then the WS-A 
> > > processor has to assume that it's something special. In fact, it's 
> > > going to try to address it as a "real address", surely? Only the RM 
> > > layer knows that "?<string>" is irrelevant to back-channel choice.
> > > 
> > > I can think of three ways of getting around this:
> > > 
> > > 1) Amend WS-Addressing Core to say: the distinguished URI is "any 
> > > URI which begins with the following distinguished string".
> > > 
> > > 2) Amend WS-Addressing Core to say: the following distinguished 
> > > metadata element or additional property means: whatever the content 
> > > of [address], use the back-channel.
> > > 
> > > 3) Put an extension element in the EPR that is routing data at 
> theapp level.
> > > 
> > > 1) & 2) involve amending WS-Addressing, which doesn't seem like a 
> > great idea.
> > > 
> > > 3) Involves no change to WS-Addressing.
> > > 
> > > If the WSDL says: anon is required, then what is the value inserted 
> > > on the wire for [reply endpoint][address]? If more definition is 
> > > required to establish that, then we seem to be losing the low-level,
> > > generic capability WS-Addressing has defined. That's what I meant by
> > > indeterminacy.
> > > 
> > > 
> > >  In talking about this with Chris Ferris, he mentioned another 
> > > alternative... instead of saying "MUST", perhaps the text related to
> > > the wsaw:Anon flag could simply say "SHOULD".  This clearly 
> > > indicates that WS-Addr's anon URI is the URI of choice, but if there
> > > are good reasons for using some other one then the processor will 
> > > allow those as well. 
> > > Let me raise another point about the WSAW wording. It  talks about 
> > > "response endpoints" in the plural. Will the required, etc apply to 
> > > all endpoints which can be responded to, i.e. [from e], [reply e], 
> > > [fault e], or is it specific to each? It seems to imply the former.
> > > 
> > > If ths is so, then it precludes routing tricks like the following 
> > > (which is practically useful):
> > > 
> > > [from endpoint] is my address if you need to send me a second (e.g. 
> > > repeated) response.
> > > [reply endpoint] = anon-URI, which is where to send your first 
> > > response, which we hope gets through.
> > > 
> > > This feature allows retrying protocols to maximize use of HTTP 
> > > responses, but not be limited by them. I would like to be able to 
> > > express this as a contractual statement: this endpoint may be anon, 
> > > this one must not be: from/prohibited, reply/optional. I have a use 
> > > case in a customer business protocol for exactly this behaviour. I 
> > > think it's a useful optimization in other contexts.
> > > 
> > > Yrs,
> > > 
> > > Alastair 
> > > 
> > > thanks, 
> > > -Doug 
> > > 
> > 
> > > 
> > > Alastair Green <alastair.green@choreology.com> 
> > > Sent by: public-ws-addressing-request@w3.org 
> > > 08/04/2006 06:59 AM 
> > > 
> > > To 
> > > 
> > > Doug Davis/Raleigh/IBM@IBMUS 
> > > 
> > > cc 
> > > 
> > > public-ws-addressing@w3.org, ws-rx@lists.oasis-open.org 
> > > 
> > > Subject 
> > > 
> > > Re: Comment on WSDL spec: use of Anonymous Element 
> > > 
> > > 
> > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > 
> > > Doug,
> > > 
> > > This is probably a dumb question, but aren't you trying to change 
the 
> > > wrong spec?
> > > 
> > > In RM you are using a single header property to indicate two things: 

> > > "we're doing back-channel here, and it's part of a logical 
connection, 
> > > identified thus".
> > > 
> > > Why can't you separate the communication of these two semantics, by 
> > > using two properties:
> > > 
> > > 1) wsa:ReplyTo = anonymous URI
> > > 2) wsrm:MakeConnection = connection identity?
> > > 
> > > 2) without 1) would be illegal.
> > > 
> > > In your example posted on the WS-RX list, you state that [reply 
> > > endpoint] is not set because MakeConnection is a "one-way message". 
But 
> > > it's a message that usually/frequently expects a reply (at a WS-A 
> > > level). Unlike many other applications, a WS-RM MC sender will 
tolerate 
> > > an empty response (no SOAP in the HTTP body), but I don't think that 

> > > stops one viewing this as a utilization of the request-reply pattern 

> > > implied by use of reply-to.
> > > 
> > > If you loosen the WSAW wording, then surely it becomes 
indeterminate. 
> > > What does "required" imply on the wire, thereafter?
> > > 
> > > Alastair
> > > 
> > > Doug Davis wrote:
> > > >
> > > > To elaborate a little on Bob's note [1], in the WSA WSDL spec, 
when 
> > > > talking about the various values for the Anonymous Element it 
lists:
> > > >
> > > > "optional": This value indicates that a response endpoint EPR in a 

> > > > request message MAY contain an anonymous URI as an address.
> > > > "required":This value indicates that all response endpoint EPRs in 
a 
> > > > request message MUST always use anonymous URI as an address.
> > > > If a response endpoint EPR does not contain the anonymous URI as 
an 
> > > > address value, then a predefined InvalidAddressingHeader fault 
defined 
> > > > in Web Services Addressing 1.0 - SOAP Binding [WS-Addressing SOAP 
> > > > Binding] MUST be generated.
> > > > "prohibited":This value indicates that any response EPRs in a 
request 
> > > > message MUST NOT use anonymous URI as an address.
> > > > If a response endpoint EPR contains the anonymous URI as an 
address 
> > > > value, then a predefined InvalidAddressingHeader fault defined in 
Web 
> > > > Services Addressing 1.0 - SOAP Binding [WS-Addressing SOAP 
Binding] 
> > > > MUST be generated.
> > > >
> > > >
> > > > The problem comes up when another spec defines their own version 
of 
> > > > anonymous - like WS-RM does.  It defines an anon URI which acts 
almost 
> > > > exactly like the WSA one in that it means "send it on the 
transport 
> > > > specific back-channel".  However, if the wsaw:Anonymous element is 
set 
> > > > to "required" then the above text would seem to imply that 
regardless 
> > > > of whether or not the RM spec is supported by the endpoint, the 
client 
> > > > can never send a wsa:ReplyTo with anything other than WSA's 
anonymous. 
> > > >  So the above text precludes another spec from ever extending WSA 
to 
> > > > define their own anon URI where from a WSA perspective its 
equivalent. 
> > > >  If the text were loosened up a bit to not mention the WSA anon 
URI 
> > > > specifically, but rather something more generic like: "... MUST 
always 
> > > > use a URI implying the transport specific back-channel" then the 
use 
> > > > of the wsaw:Anonymous element would not preclude other specs 
defining 
> > > > their own anon URI and not violate the meaning of the 
wsaw:Anonymous.
> > > >
> > > > thanks
> > > > -Doug
> > > >
> > > >
> > > >
> > > > [1] 
> > > > http://lists.w3.org/Archives/Public/public-ws-
> addressing/2006Aug/0009.html
> > > 
> > > 
Received on Wednesday, 9 August 2006 13:45:55 GMT

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