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

From: Martin Gudgin <mgudgin@microsoft.com>
Date: Thu, 14 Jul 2005 11:04:22 -0700
Message-ID: <DD35CC66F54D8248B6E04232892B63380653546D@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>
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.
 
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.
 
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 18:05:53 GMT

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