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RE: LC 76 - What makes a msg WS-A?

From: Martin Gudgin <mgudgin@microsoft.com>
Date: Thu, 14 Jul 2005 12:38:47 -0700
Message-ID: <DD35CC66F54D8248B6E04232892B633806574CEF@RED-MSG-43.redmond.corp.microsoft.com>
To: "David Hull" <dmh@tibco.com>
Cc: "Katy Warr" <katy_warr@uk.ibm.com>, <public-ws-addressing@w3.org>
Why is it a problem if a message which doesn't have wsa:Action in it is
NOT subject to 'validation' (what does that mean, BTW) by the receiver?

Gudge


________________________________

	From: David Hull [mailto:dmh@tibco.com] 
	Sent: 14 July 2005 20:29
	To: Martin Gudgin
	Cc: Katy Warr; public-ws-addressing@w3.org
	Subject: Re: LC 76 - What makes a msg WS-A?
	
	
	Martin Gudgin wrote: 

		OK, I'm confused.
		 
		Why do you conclude that the answer to my question
"Given that the wsa:Action header is mandatory, isn't it the presence of
that header?" is 'No'. 
		 
		I would have come to the opposite conclusion;
		 
		I have an endpoint that understands WS-Addressing. It
receives a message that contains wsa:ReplyTo but no wsa:Action. It
generates a fault. Seems pretty straightforward to me.

	Sure.  That is a perfectly straightforward rule.  In fact, it's
implied by what we say in section 3.3.
	
	I thought you were trying to answer the question "When is an
incoming message deemed to be a WS-Addressing message and therefore
subject to the appropriate WS-Addressing validation?" with (rephrasing
the reply as a statement) "It's subject to WSA validation if the
wsa:Action header is present."  And of course, this clearly won't work,
since it specifically doesn't try to validate a message with wsa:ReplyTo
and no wsa:Action.
	
	If you meant something else, then never mind.  It's probably not
worth sorting.
	

		 
		I have an endpoint that doesn't understand
WS-Addressing. It receives a message that contains one or more wsa:
headers, it either ignores them or generates a mustUnderstand fault
depending on whether those headers are marked mustUnderstand='true' or
not. Again, seems pretty straightforward to me.

	Sure.  As I said, we're talking about behavior of endpoints, not
properties of messages.
	
	As DaveO says, the interesting case is that of an endpoint that
wants to accept non-WSA messages without complaint but also handle WSA
messages properly.
	

		 
		Gudge


________________________________

			From: David Hull [mailto:dmh@tibco.com] 
			Sent: 14 July 2005 18:02
			To: Martin Gudgin
			Cc: Katy Warr; public-ws-addressing@w3.org
			Subject: Re: LC 76 - What makes a msg WS-A?
			
			
			Martin Gudgin wrote: 

				 


________________________________

				From: David Hull [mailto:dmh@tibco.com] 
				Sent: 14 July 2005 16:32
				To: Martin Gudgin
				Cc: Katy Warr;
public-ws-addressing@w3.org
				Subject: Re: LC 76 - What makes a msg
WS-A?
				
				
				Is this really a question of how to
support both WSA and old-style HTTP requests on the same endpoint?  
				[MJG] I don't know, I didn't ask the
original question.
				

			Hmm ... my message was in-reply-to yours, but
the question was really aimed more at Katy.  Maybe we need BPEL here
:-).
			

				
				  I.e., if I don't see any WSA headers
at all, I assume it's an old-style request and act accordingly, but if I
see anything WSA, I follow the rules in section 3? 
				[MJG] I guess one could do that... 
				

			Well, one should do something to ensure that
old-style requests are accepted as such.
			


				The tricky bit is that, since MAPs like
[destination] and [reply endpoint] can default, a message with no wsa:
elements on the wire could still be assigned values for some of its
MAPs, since the infoset will still have values for the corresponding
elements. 
				[MJG] Which Infoset are you talking
about? The XML Infoset has no such values.
				

			Sorry, I didn't get that quite right.  I was
going by section 3.2, particularly the descriptions of wsa:To:
			
			

				This OPTIONAL element (whose content is
of type xs:anyURI) provides the value for the [destination] property. If
this element is NOT present then the value of the [destination] property
is "http://www.w3.org/@@@@/@@/addressing/anonymous"
<http://www.w3.org/@@@@/@@/addressing/anonymous> .
				


			(and similarly for wsa:ReplyTo). I initially
misread this as stating that the element defaulted, as opposed to the
MAP.  So s/since the infoset will still have values for the
corresponding elements/since the properties are defaulted in the absence
of the corresponding elements in the infoset/.  This sort of confusion
could be seen as an argument against the two-layered approach (or simply
as an argument that I read too quickly).
			
			In any case, you can't simply look at the
abstract properties and say "some WSA properties are defined, so it's a
WSA message".
			

				
				   So either we have to drop down to
look at the infoset level, and in particular at the non-defaulted
elements in the infoset, or we have to find some marker that can't be
defaulted away.  This is why the [action] property looks significant
here.  But on the other hand, what if I include a wsa:ReplyTo element
and no action?  By the "it's WSA iff [action] is present" rule, that's
not a WSA message and therefore not an error.  This seems wrong. 
				[MJG] Why does it seem wrong?
				

			It seems wrong not to fault for a message that
contains a wsa:ReplyTo on the wire but not a wsa:Action.
			


				Put another way, when would one get a
fault for omitting [action]? 
				[MJG] Whenever another wsa: header is
present in a message.

			In other words, the answer to your question
("Given that the wsa:Action is mandatory, isn't it the presence of that
header?") is "No."
			
			This is why at the Berlin meeting we tried to
make sure that all the possibilities were covered for various
combinations of the MAPs.  I believe we've satisfied ourselves that they
are, but perhaps we need to revisit this work?
			

				
				
				Martin Gudgin wrote: 

				Given that the wsa:Action is mandatory,
isn't it the presence of that header?
				 
				Gudge


________________________________

				From:
public-ws-addressing-request@w3.org
[mailto:public-ws-addressing-request@w3.org] On Behalf Of Katy Warr
				Sent: 14 July 2005 16:07
				To: public-ws-addressing@w3.org
				Subject: LC 76 - What makes a msg WS-A?
				
				

				Please could we discuss the following in
the context of LC76? 
				
				When is an incoming message deemed to be
a WS-Addressing message and therefore subject to the appropriate
WS-Addressing validation?   Is it based on the presence of any
WS-addressing Message Addressing Property?  For example, does a message
containing a reference parameter (but no other WS-Addressing
information) need to result in a MessageAddressingHeaderRequired?    Or,
for example, does the declaration of the wsa namespace rendor the
message WS-Addressing? 
				
				Thanks 
				Katy
Received on Thursday, 14 July 2005 19:40:16 GMT

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