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

From: <sylvain.marie@fr.schneider-electric.com>
Date: Thu, 4 Jun 2009 16:19:47 +0200
To: Doug Davis <dug@us.ibm.com>
Cc: antoine.mensch@odonata.fr, public-ws-addressing@w3.org, public-ws-addressing-request@w3.org
Message-ID: <OF31008AA5.03270281-ONC12575CB.004D78DE-C12575CB.004EB768@schneider-electric.com>

> Some implementations allow for SOAP headers to be service specific

Sorry I made a shortcut in my last post. I meant all elements related to
the different WS-* standards - as opposed to all business elements defined
by the user.

> I consider checking for a valid wsa:Action as a WSA check.

Yes, but this does not require that the driver asks about the service
metadata.
For example we use the standard java UnsupportedOperationException, for the
business layer to indicate that an invocation of {action, message} is not
supported. If WS-Addressing was used for that invocation, the driver will
then convert it to an "action Not Supported" fault. this clearly makes the
services independent from all proocol-related stuff.
Of course the separation would be different in other langagues...

Sylvain

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








                                                                           
             Doug Davis                                                    
             <dug@us.ibm.com>                                              
                                                                         A 
             04/06/2009 15:54          Sylvain Marie/FR/Schneider@Europe   
                                                                        cc 
                                       antoine.mensch@odonata.fr, Bob      
                                       Freund                              
                                       <bob.freund@hitachisoftware.com>,   
                                       public-ws-addressing@w3.org,        
                                       public-ws-addressing-request@w3.org 
                                                                     Objet 
                                       Re: [WS-Addressing] issue           
                                       concerning reliable One-Way MEP     
                                       detection                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           





It depends on the implementation.  Some implementations allow for SOAP
headers to be service specific - and that's the case I was thinking of when
I compared MustUnderstand checking those headers to checking for
one-wayness. For your implementation choice, I agree that you're in a bit
of a bind - although, I consider checking for a valid wsa:Action as a WSA
check.

thanks
-Doug
______________________________________________________
STSM |  Standards Architect  |  IBM Software Group
(919) 254-6905  |  IBM 444-6905  |  dug@us.ibm.com
The more I'm around some people, the more I like my dog.

                                                                           
 sylvain.marie@fr.                                                         
 schneider-electri                                                         
 c.com                                                                     
 Sent by:                                                               To 
 public-ws-address       Doug Davis/Raleigh/IBM@IBMUS                      
 ing-request@w3.or                                                      cc 
 g                       antoine.mensch@odonata.fr, Bob Freund             
                         <bob.freund@hitachisoftware.com>,                 
                         public-ws-addressing@w3.org,                      
 06/04/2009 09:41        public-ws-addressing-request@w3.org               
 AM                                                                Subject 
                         Re: [WS-Addressing] issue concerning reliable     
                         One-Way MEP detection                             
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           





> checking all of the mU headers seems akin to checking the service's
metadata for one-wayness.

Well although it makes sense, I do not fully agree with this. In my opinion
the headers relate to the non-fonctional aspect of the service (the
endpoint's policy, the processing pipe, some ws-* features...) ; while the
action relates to the business aspect (i.e. it represents the operation to
invoke in the end). In our implementation the core driver only knows the
non-fonctional and delegates everything related to the functional part to
higher layers. It would not be very elegant for the driver to ask a service
if such or such operation is one way, whereas all other MEP and
addressing-related stuff is automatically handled...

Best regards,

Sylvain

Inactive hide details for Doug Davis <dug@us.ibm.com>Doug Davis
<dug@us.ibm.com>


                                                                           
 Doug Davis                                                                
 <dug@us.ibm.c                                                             
 om>                                                                       
                                                                           
                                                                           
 04/06/2009                                                              A 
 14:26                                                                     
                    Bob Freund <bob.freund@hitachisoftware.com>            
                                                                           
                                                                           
                                                                        cc 
                                                                           
                    antoine.mensch@odonata.fr,                             
                    public-ws-addressing@w3.org,                           
                    public-ws-addressing-request@w3.org, Sylvain           
                    Marie/FR/Schneider@Europe                              
                                                                           
                                                                           
                                                                     Objet 
                                                                           
                    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
______________________________________________________
STSM | Standards Architect | IBM Software Group
(919) 254-6905 | IBM 444-6905 | dug@us.ibm.com
The more I'm around some people, the more I like my dog.
                                                                           
 Bob Freund                                                                
 <bob.freund@hitachisoftware                                               
 .com>                                                                     
 Sent by:                                                               To 
 public-ws-addressing-reques           sylvain.marie@fr.schneider-electric 
 t@w3.org                              .com                                
                                                                        cc 
                                       public-ws-addressing@w3.org,        
 06/04/2009 07:05 AM                   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


                                                                           
 <0F385492.jpg>          Sylvain MARIÉ                                     
                         Embedded Software Engineer                        
                         sylvain.marie@schneider-electric.com              
                         +33 (0)4 76 57 67 31 / 34 67 31                   
                                                                           







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Received on Thursday, 4 June 2009 14:20:32 GMT

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