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Re: wsa:To -> SOAP1.2's ImmediateDestination

From: Marc Hadley <Marc.Hadley@Sun.COM>
Date: Fri, 19 Aug 2005 15:32:26 -0400
To: Mark Baker <distobj@acm.org>
Cc: public-ws-addressing@w3.org
Message-id: <20751F19-12E5-40B8-BD5B-A536A055B11C@Sun.COM>
On Aug 19, 2005, at 11:10 AM, Mark Baker wrote:
>> wsa:To gives the value of the ultimate recipient, but the SOAP
>> binding is hop-by-hop so ImmediateDestination could be the address of
>> a SOAP intermediary instead of the ultimate recipient.
> Sorry, I don't follow.  I don't know what it means for the WS-A SOAP
> binding to be hop-by-hop, since the SOAP processing model is end-to- 
> end.
See the SOAP 1.2 Rec[1]:

The SOAP Processing Model enables SOAP nodes that include the  
mechanisms necessary to implement one or more features to express  
such features within the SOAP envelope as SOAP header blocks (see 2.4  
Understanding SOAP Header Blocks). Such header blocks can be intended  
for any SOAP node or nodes along a SOAP message path (see 2.3  
Targeting SOAP Header Blocks). The combined syntax and semantics of  
SOAP header blocks are known as a SOAP module, and are specified  
according to the rules in 3.3 SOAP Modules.

In contrast, a SOAP protocol binding operates between two adjacent  
SOAP nodes along a SOAP message path. There is no requirement that  
the same underlying protocol is used for all hops along a SOAP  
message path...

Certain features might require end-to-end as opposed to hop-by-hop  
processing semantics. Although the SOAP Protocol Binding Framework  
allows end-to-end features to be expressed outside the SOAP envelope,  
no standard mechanism is provided for the processing by  
intermediaries of the resulting messages...

> Also, in the Req/Resp MEP, there's some ambiguity about the
> definition of the ImmediateDestination property;
> "The identifier of the immediate destination of an outbound message."
>  -- http://www.w3.org/TR/2003/REC-soap12-part2-20030624/ 
> #tabreqresprops
> (where "immediate destination" is undefined)
> However, the description of its value seems unambiguous that it's
> identifying the ultimate recipient;
> "An identifier (URI) that denotes the responding SOAP node"
>  -- http://www.w3.org/TR/2003/REC-soap12-part2-20030624/#tabreqcon
Yes, but from a hop-by-hop binding perspective, the next node along  
the SOAP message path is the responder, its not necessarily the  
ultimate recipient (though it would be for the penultimate node).


[1] http://www.w3.org/TR/2003/REC-soap12-part1-20030624/#soapfeature

Marc Hadley <marc.hadley at sun.com>
Business Alliances, CTO Office, Sun Microsystems.

Received on Friday, 19 August 2005 19:32:43 UTC

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