Alastair, I think I addressed these
in response to your other note.
-Doug
Alastair Green <>
Sent by:
08/08/2006 11:42 AM
To
Christopher B Ferris/Waltham/IBM@IBMUS
cc
, ,
Subject
Re: [ws-rx] Re: Comment on WSDL spec:
use of Anonymous Element
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:
blog: http://www.ibm.com/developerworks/blogs/dw_blog.jspa?blog=440
phone: +1 508 377 9295
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 [as
per 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 <>
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 <>
> > 08/04/2006 10:57 AM
> >
> > To
> >
> > Doug Davis/Raleigh/IBM@IBMUS
> >
> > cc
> >
> > ,
,
> > ,
,
,
> > ,
,
,
> > ,
,
anil.
>
> > , ,
Anthony Nadalin/Austin/IBM@IBMUS,
> > ,
,
,
> > ,
,
,
> > ,
,
,
blake.
> > ,
,
,
> > ,
,
> ,
> > ,
Charles Levay/Raleigh/IBM@IBMUS,
> > ,
Christopher B Ferris/Waltham/IBM@IBMUS,
> > ,
,
"'von Riegen, Claus'"
> > <>,
,
> ,
> > ,
"'Burdett, David'" <>,
> > ,
Diane Jordan/Raleigh/IBM@IBMUS,
> > ,
,
,
>
> > , "'David Orchard'" <>,
,
> > ,
,
,
> > ,
,
eric.
> > ,
,
,
> > ,
,
"'Gilbert Pilz'"
> > <>,
,
,
> > ,
,
,
> > ,
,
,
> > ,
,
jeff.
> > ,
,
,
> > ,
,
,
joeri.
> > ,
,
john.
>
> > , ,
,
,
k-
> > ,
,
,
> > ,
,
"'Lei Jin'" <>,
> > ,
"'Mark Little'" <>,
> > "'Schenecker, Mark'" <>,
"'de Boer, Martijn'"
> > <>,
"'Raepple, Martin'" <>,
> > ,
,
>
> > , ,
,
"'Bechauf, Michael'"
> > <>,
,
,
> > ,
,
,
> > ,
,
,
> > ,
,
>
> > , ,
,
,
> > ,
,
,
> > ,
,
Richard
> > Salz/Cambridge/IBM@IBMUS, ,
,
> > "'Patil, Sanjay'" <>,
,
> > , Scott Hinkelman/Austin/IBM@IBMUS, ,
> > ,
,
,
> > "'Rossmanith, Stefan'" <>,
"'Winkler, Steve'"
> > <>,
,
,
> > ,
,
,
> > ,
,
,
> > "'Yalcinalp, Umit'" <>,
> > , "'Shipkowitz, Vicki'" <>,
> > , "'Videlov, Vladimir'" <>,
Martin Chapman
> > <>
> >
> > 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 <>
> > Sent by:
> > 08/04/2006 06:59 AM
> >
> > To
> >
> > Doug Davis/Raleigh/IBM@IBMUS
> >
> > cc
> >
> > ,
> >
> > 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
> >
> >
