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RE: Issue i044: Definition of the rules to reply to a message in Core 3.2

From: Jonathan Marsh <jmarsh@microsoft.com>
Date: Tue, 8 Feb 2005 10:42:12 -0800
Message-ID: <7DA77BF2392448449D094BCEF67569A506763683@RED-MSG-30.redmond.corp.microsoft.com>
To: "Doug Davis" <dug@us.ibm.com>
Cc: "Hugo Haas" <hugo@w3.org>, <public-ws-addressing@w3.org>
We seem to be working with different definitions of "undefined", perhaps
that is the source of our disconnect.

 

I propose we change "is undefined" in Hugo's proposal to "is undefined
by this specification" or "is out of scope of this specification" to
make it clear that we're not removing useful behavior defined elsewhere
(like the ability to predict where a fault goes when WSA is not
engaged), but only adding behavior (the ability to specify where a fault
goes using wsa:FaultTo.)

 

I prefer a design where WSA is transparent with regard to where replies
and faults go unless you specifically engage wsa:ReplyTo and
wsa:FaultTo.  I agree with Doug that WS-A should not override the useful
behavior of lower-level specs to make those behaviors implementation
dependent, nor should it preclude the possibility of higher-level specs
layering useful behavior on top of WS-A.

 

 

________________________________

From: Doug Davis [mailto:dug@us.ibm.com] 
Sent: Monday, February 07, 2005 4:54 PM
To: Jonathan Marsh
Cc: Hugo Haas; public-ws-addressing@w3.org
Subject: RE: Issue i044: Definition of the rules to reply to a message
in Core 3.2

 


>From the client's point of view I'd like to know exactly where my
responses (either normal responses or faults) are going to go.  Assuming
WSA is "on" w/o a wsa:FaultTo I have no idea where my fault will go.
Per your suggestion it _might_ go back on the http response flow but
that's only if the service deems it to not be a normal response but
instead something special.  If however the service decides that faults
are no different than responses (and per sec 3 of the WSA spec, WSA
itself thinks faults are replies so that seems like a perfectly valid
way to think of them) then the service is free to send the fault to the
wsa:ReplyTo - its just a response.  What's a client to do?  Basically,
wsa:FaultTo becomes required if I want to have a deterministic outcome.
And that's really all I'm looking for.  While I do have a preference as
to what the semantic rules should be, I'm more interested in just
getting the WSA spec to be specific about what rules people should
follow and expect of a WSA compliant endpoint - whatever those rules may
be.  So, if the WG decides that no wsa:FaultTo means "use default SOAP
behavior (as if WSA wasn't "on") for Faults" then that's fine - but lets
have the spec actually say that instead of assuming people will come to
that conclusion on their own. 
I have similar concerns about replies and missing wsa:ReplyTo but we'll
leave that one for later  :-) 
-Dug 




"Jonathan Marsh" <jmarsh@microsoft.com> 

02/07/2005 07:34 PM 

To

Doug Davis/Raleigh/IBM@IBMUS 

cc

"Hugo Haas" <hugo@w3.org>, <public-ws-addressing@w3.org> 

Subject

RE: Issue i044: Definition of the rules to reply to a message in Core
3.2

 

 

 




I think I understood you.  I am suggesting that we don't advise users of
WSA to avoid the unconstrained bit of the spec.  Though that part is
unconstrained by WS-A, there is no reason to think it's dangerous and
warn people off.  At least you haven't proved it to be so yet... 
  
For instance, say I have a deployed service with 10 in-out operations.
I decide to upgrade my service so that one of those operations accepts
and processes ReplyTos.  Now I'm a WS-A user.  Under your suggestion, I
would be encouraged to also add FaultTos, not just to the operation I
modified, but to the other 9 operations as well.  If explicit FaultTos
are a good idea, explicit ReplyTos probably are as well, so I should add
those to the remaining 9 operations as well.  Seems like a lot of
overhead for a small change to one operation.  It's hard to see why the
practice I used yesterday to send replies and faults has somehow become
dangerous today because I'm now a WS-A user. 
  

 

________________________________


From: Doug Davis [mailto:dug@us.ibm.com] 
Sent: Monday, February 07, 2005 12:37 PM
To: Jonathan Marsh
Cc: Hugo Haas; public-ws-addressing@w3.org
Subject: RE: Issue i044: Definition of the rules to reply to a message
in Core 3.2 
  

Jonathan, 
 I think you might have misread my note - or perhaps I wasn't clear. 
I wasn't suggesting that WSA should say what an impl. should do 
in the absence of a wsa:FaultTo header but rather suggesting 
that WSA should encourage users of WSA to avoid this "unconstrained" 
bit of the spec and be explicit in their messages and include a 
wsa:FaultTo. 
-Dug 

"Jonathan Marsh" <jmarsh@microsoft.com> 

02/07/2005 11:56 AM 

 

To

Doug Davis/Raleigh/IBM@IBMUS, "Hugo Haas" <hugo@w3.org> 

cc

<public-ws-addressing@w3.org> 

Subject

RE: Issue i044: Definition of the rules to reply to a message in Core
3.2


  

 

  

 





I suspect the intent is more along the lines of "is unconstrained by
this specification" (or at least, I'd prefer those words.)  I'd expect
in the absence of FaultTo that most faults would be sent wherever they
would have if WS-A was not in use.

It's WS-A's business to introduce a specific feature (FaultTo) and its
behavior.  It's not WS-A's business to constrain what might happen when
WS-A features are not engaged.  Nor unduly limit the ability of future
specs to build on this feature.  I think the rules Hugo proposes do this
pretty cleanly.

________________________________________
From: public-ws-addressing-request@w3.org
[mailto:public-ws-addressing-request@w3.org] On Behalf Of Doug Davis
Sent: Monday, February 07, 2005 5:40 AM
To: Hugo Haas
Cc: public-ws-addressing@w3.org
Subject: Re: Issue i044: Definition of the rules to reply to a message
in Core 3.2


Hugo wrote on 02/07/2005 04:44:08 AM:
...
> Otherwise, if the reply is a fault message and the incoming message's
> [fault endpoint] message addressing property is not empty, select the
> EPR from this property. If the [fault endpoint] property is empty, the
> behavior of the recipient of the incoming message is undefined.

In particular, the "... is undefined." in the last sentence. 
I read this to mean that as the sender of the incoming message I 
can not make any assumption about where any possible Fault would go 
if I did not include a wsa:FaultTo EPR in the incoming message. 
Is this correct?  If so, does this not have the effect of making the
wsa:FaultTo 
EPR required for all cases except in a one-way fire-n-forget scenario? 
If so, that's ok (I guess :-), but I think it would be helpful to 
encourage people (with a 'SHOULD' someplace) to include a wsa:FaultTo 
so that they avoid 'undefined' behavior and risk interop issues. 
-Dug 
Received on Tuesday, 8 February 2005 18:42:22 GMT

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