Re: [WS-Addressing] issue concerning reliable One-Way MEP detection

Maybe but the spec doesn't actually say that.
However, I think there's another thing that implementations would need to 
worry about.  Even in a one-way message should the service be expected to 
return mustUnderstand faults or soap version faults? While its not 
required to, those sure are nice things to return if you can.  So in those 
cases I would hope that an HTTP 202 wouldn't be automatically returned 
before these two checks were done - and checking all of the mU headers 
seems akin to checking the service's metadata for one-wayness.

thanks
-Doug
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Bob Freund <bob.freund@hitachisoftware.com> 
Sent by: public-ws-addressing-request@w3.org
06/04/2009 07:05 AM

To
sylvain.marie@fr.schneider-electric.com
cc
public-ws-addressing@w3.org, antoine.mensch@odonata.fr
Subject
Re: [WS-Addressing] issue concerning reliable One-Way MEP detection






I would have thought that a wsa:replyTo element containing the child 
<wsa:Address> http://www.w3.org/2005/08/addressing/none</wsa:Address> 
could be used to infer a one-way message.
-bob

On Jun 3, 2009, at 10:05 AM, sylvain.marie@fr.schneider-electric.com 
wrote:

Hi,

I have been working for the fast few years on Devices Profile for Web 
Services (DPWS) specification, and especially on an implementation (
https://forge.soa4d.org/). DPWS 1.0 was originally referring to WSA 
member's submission, while DPWS 1.1 specification has now moved to 
WS-Addressing 1.0.

WS-Addressing specifies how messages corresponding to different Message 
Exchange Patterns (MEP) are sent. However it does not seem to specify a 
reliable way to detect which MEP is actually in use. In particular the 
One-Way MEP may not be detected reliably, which prevents devices to make 
any optimisation (for example, send the empty HTTP response for SOAP/HTTP 
binding). The only alternative is to inspect the actionUri and refer to a 
service's WSDL in order to retrieve the appropriate MEP.

In DPWS implementations we think that the driver should be able to 
implement the default processing chain without necessary knowing about the 
web services deployed on top of it. We first thought about using the 
absence of "replyTo" as a good indicator for a One-Way MEP but since 
WS-Addressing 1.0 this does not work any more, as replyTo always have a 
default value ("anonymous"). No we are thinking about using the absence of 
"messageId" as a clue to detectt One-Way MEPs but this is clearly a hack 
and not something we may rely on in he future.

What is the opinion of WS-Addressing's WG about this ? Thank you very much 
in advance,

Best regards,


Sylvain


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Sylvain MARIÉ
Embedded Software Engineer
sylvain.marie@schneider-electric.com
+33 (0)4 76 57 67 31 / 34 67 31