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RE: [issue 6432] - a modest proposal

From: Geoff Bullen <Geoff.Bullen@microsoft.com>
Date: Tue, 12 May 2009 16:13:44 -0700
To: Gilbert Pilz <gilbert.pilz@oracle.com>
CC: Doug Davis <dug@us.ibm.com>, "public-ws-resource-access@w3.org" <public-ws-resource-access@w3.org>
Message-ID: <5AAAA6322448AA41840FC4563A30D6E847585C6700@NA-EXMSG-C122.redmond.corp.microsoft.com>
Gil,
It is not just a simple case of comparing XML, but let's start here...

Using the RED/BLUE example discussed below...


1)  Using mode, we send:

[Body]
<Subscribe>
  <Delivery mode=".../BLUE">
    <NotifyTo>  ... </NotifyTo>
  </Delivery>
</Subscribe>


2)  The equivalent without mode would be:

[Header]
<UseA mustUnderstand="1"/>
<UseB mustUnderstand="1"/>
<UseD mustUnderstand="1"/>

[Body]
<Subscribe>
  <NotifyTo>  ... </NotifyTo>
  <A />
  <B />
  <D />
</Subscribe>

Maybe some of the A, B, D elements are actually inside the NotifyTo EPR, but it does not matter for this discussion.

--Geoff


From: Gilbert Pilz [mailto:gilbert.pilz@oracle.com]
Sent: Tuesday, May 12, 2009 1:08 PM
To: Geoff Bullen
Cc: Doug Davis; public-ws-resource-access@w3.org
Subject: Re: [issue 6432] - a modest proposal

Geoff,

As I said before, please show me a specific message (in XML) using Mode. I will show you the same message without Mode. We can then compare and contrast.

- gp

On 5/12/2009 9:57 AM, Geoff Bullen wrote:
Thanks Gil,

Based on the information below, let us look at the following example:

The event source has implemented four different extensibility points A, B, C, D.
The event source has only validated (via interop testing) two possible combinations: A,B,C and A,B,D.
These are the only two combinations supported by the event source.

If mode is used, one can easily create two modes RED = A,B,C and BLUE = A,B,D and the client can simply send this mode, along with any required information, to the event source for processing.

Without mode, there are a number of interesting situations:

What if the client does not send mU headers and sends elements A,B,C,D? ( Can you ignore some of them?)

What if the client does send mU headers and sends elements A,B,C,D?  (Does must understand = must use?)

What if B required no information to be sent from the client to the event source (only the fact that the client wants to use B)?  Does that mean you would have to create an empty element B, just to send something?  Or use an mU header?  Using mode, both RED and BLUE infer B, no need to send an empty element at all.

The event source, without mode, now seems to have a much more complicated task of trying to figure out if the client wants RED, BLUE or if it's a fault situation - illegal combination?  For example, without mode, the combination A,B would have to be seen as illegal.  With mode = RED, the event server could use the default values for C and proceed.

Without mode, would the combination B,C be legal or illegal?

Think of the documentation that the event source will generate in order for the client to understand what is supported.  It will almost certainly talk about RED mode and BLUE mode and point out what is required to support both.  The natural extension to this is for the client to simply select RED or BLUE when doing the subscribe.

Gets more complicated if A is only a partial implementation and A (with one setting) supports RED and A (with a different setting) supports BLUE.

There are probably more...

The point is, as has been stated many times, you can always find a way to solve any problem with any of the solutions proposed, but some solutions are better at handling certain situations than others.  Mode is better at handling grouping cases where there is a small number of supported configurations which contain groups of characteristics.  Other ways are better at handling the opposite case, where the event source supports a variety of characteristics that can be combined in different ways.  It seems that we should support both options.

--Geoff

From: Gilbert Pilz [mailto:gilbert.pilz@oracle.com]
Sent: Monday, May 11, 2009 5:25 PM
To: Geoff Bullen
Cc: Doug Davis; public-ws-resource-access@w3.org<mailto:public-ws-resource-access@w3.org>
Subject: Re: [issue 6432] - a modest proposal

Geoff,

I believe I can speak for those of us who would like to eliminate the Delivery element and the Mode attribute.

1.) Use the extensibility that already exists in Subscribe and the various EPRs to express your extensions. For example, request an extension by adding a child element to Subscribe.

2.) If necessary (and it's important to note that it is not always necessary), accompany the extension with a SOAP mU header that indicates that an extension is being used.

3.) Use WS-Policy assertions to indicate which extensions are supported by an Event Source. These policies assertions can be attached to WSDLs and retrieved by the normal mechanisms for obtaining a WSDL (HTTP, WS-Mex), or they may be retrieved directly via WS-MEX, or they may be retrieved via some other mechanism.

- gp

On 5/11/2009 12:02 PM, Geoff Bullen wrote:
Doug,
Can we quickly cover what your proposed solution to replace mode really is at the moment, please?
Is it:

Use extensions to EPR and Subscribe and mU headers?  Remember that Mode should fault if it is not a valid mode, so mU would be the thing that allows that functionality.

Use runtime policy negotiation with the policy statements in the NotifyTo EPR.

Some combination of the two approaches.
I am kind of assuming it's a) but I want to make sure before I comment further.
Thanks,
Geoff

From: public-ws-resource-access-request@w3.org<mailto:public-ws-resource-access-request@w3.org> [mailto:public-ws-resource-access-request@w3.org] On Behalf Of Doug Davis
Sent: Saturday, May 09, 2009 10:35 AM
To: public-ws-resource-access@w3.org<mailto:public-ws-resource-access@w3.org>
Subject: Re: [issue 6432] - a modest proposal


This might be true if someone could show why the proposed solution doesn't work for both.  To date, the only consistent complaint about the proposal is that is may require some code changes.  I believe Gil even proposed a challenge [1] to address this type of concern - sadly, no one has taken him up on it.

[1] http://lists.w3.org/Archives/Public/public-ws-resource-access/2009Apr/0135.html

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



Bob Freund <bob@freunds.com><mailto:bob@freunds.com>
Sent by: public-ws-resource-access-request@w3.org<mailto:public-ws-resource-access-request@w3.org>

05/07/2009 08:42 PM

To

Yves Lafon <ylafon@w3.org><mailto:ylafon@w3.org>

cc

David Snelling <David.Snelling@UK.Fujitsu.com><mailto:David.Snelling@UK.Fujitsu.com>, Gilbert Pilz <gilbert.pilz@oracle.com><mailto:gilbert.pilz@oracle.com>, Asir Vedamuthu <asirveda@microsoft.com><mailto:asirveda@microsoft.com>, Doug Davis/Raleigh/IBM@IBMUS, "public-ws-resource-access@w3.org"<mailto:public-ws-resource-access@w3.org> <public-ws-resource-access@w3.org><mailto:public-ws-resource-access@w3.org>

Subject

Re: [issue 6432] - a modest proposal







There seems like there is a big-systems use of notification as well as
a small-device market for the same protocol.
The difference seems to be the extent to which negotiation protocols
and additional features might be available.
It sounds like finding a way like this to make both ways possible
might be what is needed.
-bob

On May 6, 2009, at 4:19 PM, Yves Lafon wrote:

> On Thu, 9 Apr 2009, Bob Freund wrote:
>
>> Would it be too bold to suggest folks consider to move NotifyTo to
>> be a child of Subscribe?
>> that way, then Delivery could be used (as an xs:Any) extension
>> point, used by other specifications to mean anything they want at
>> at cost of merely setting a SOAP mU header on delivery to get the
>> fault behavior.  Of course, the fault would change from
>> modeNotRecognized to SOAP mU Fault, but the other stuff would still
>> work.
>> Is that half-way-ish approach that folks could consider?
>
> The main issue is still the addition of the mU in the default version.
> How about adding a specific mode (like 'anonymous') that would
> trigger the use of the other approach.
> That way we would have the "historic" use of mode, and the new
> version using the same trigger mechanism, allowing old
> implementation to interoperate with newer ones, while keeping a way
> to use the new version in all the cases where the old version would
> not be optimal.
> Would that make sense for both camp ?
>
>>
>> On Apr 9, 2009, at 11:09 AM, David Snelling wrote:
>>
>>> Folks,
>>> I will try this with colour:
>>> <s:Envelope . . .>
>>> <s:Header>
>>>   <wsa:Action>http://www.w3.org/2009/02/ws-evt/Subscribe<wsa:Action>
>>>   <wsa:MessageID>uuid:d7c5726b-de29-4313-b4d4-b3425b200839</
>>> wsa:MessageID>
>>>   <wsa:ReplyTo>
>>>     <wsa:Address>http://www.w3.org/2005/08/addressing/anonymous</
>>> wsa:Address>
>>>   </wsa:ReplyTo>
>>>   <wsa:To>http://www.example.org/oceanwatch/EventSource</wsa:To>
>>> </s:Header>
>>> <s:Body>
>>>   <wse:Subscribe>
>>>     <wse:Delivery>
>>>       <wse:NotifyTo>
>>>         <wsa:Address>http://www.w3.org/2005/08/addressing/
>>> anonymous</wsa:Address>
>>>       </wse:NotifyTo>
>>>     </wse:Delivery>
>>>   </wse:Subscribe>
>>> </s:Body>
>>> </s:Envelope>
>>> Red: General SOAP layer.
>>> Green: WSE Application Layer.
>>> Blue: WS-Addressing infrastructure.
>>> OK the important point is that no matter what delivery model I
>>> want to use, I only change blue and red text. The beauty of
>>> Eventing is that the green XML stays the same across all the use
>>> cases we have discussed.
>>> For wse:Push: In the blue NotifyTo EPR include a sensible address.
>>> For wsman:PushWithAck: In the blue NotifyTo EPR include an address
>>> and possibly policy indicating reliable delivery required. This
>>> will means some more stuff will show up in red and possibly orange
>>> (for the reliable messaging) on the delivered messages.
>>> For wsman:Pull: In blue include either an MC special URI or the
>>> actual address of a WS-Notification Pull point.
>>> For wsman:Events: This is the same as wsman:PushWithAck which
>>> affects only the blue, red, and orange XML, but using a format
>>> provided by WS-Management V2.0 in some pink XML.
>>> Notice: No Green XML changes!!!
>>> In fact existing implementations have to change NOTHING in their
>>> semantics. They will need to understand the new namespace and
>>> learn not to look for the Mode attribute. The semantics of
>>> Eventing do not change.
>>> On 08 Apr 2009, at 20:08, Gilbert Pilz wrote:
>>>> I think that, in this context, the term "opaque" might be a red-
>>>> herring. The point is that a URI like "http://docs.oasis-open.org/ws-rx/wsmc/200702/anonymous?id=1447d9c0-246a-11de-8c30-0800200c9a66
>>>> " requires neither more nor less understanding at the application
>>>> layer (in this case the component that processes wse:Subscribe
>>>> requests) than a URI like "http://www.w3.org/2005/08/addressing/anonymous
>>>> " or "http://webservice.bea.com/ohai/lolcatz"<http://webservice.bea.com/ohai/lolcatz>.
>>>> I think part of the problem might be that we are all assuming
>>>> different processing models. Look at the following request and
>>>> tell me how you think it should be handled. If you could be
>>>> somewhat specific about which layer (ws-addr layer, general SOAP
>>>> layer, wse:Subscribe logic, etc.) does/checks what, that would be
>>>> helpful:
>>>> <s:Envelope . . .>
>>>> <s:Header>
>>>>   <wsa:Action>http://www.w3.org/2009/02/ws-evt/
>>>> Subscribe<wsa:Action>
>>>>   <wsa:MessageID>uuid:d7c5726b-de29-4313-b4d4-b3425b200839</
>>>> wsa:MessageID>
>>>>   <wsa:ReplyTo>
>>>>     <wsa:Address>http://www.w3.org/2005/08/addressing/anonymous</
>>>> wsa:Address>
>>>>   </wsa:ReplyTo>
>>>>   <wsa:To>http://www.example.org/oceanwatch/EventSource</wsa:To>
>>>> </s:Header>
>>>> <s:Body>
>>>>   <wse:Subscribe>
>>>>     <wse:Delivery>
>>>>       <wse:NotifyTo>
>>>>         <wsa:Address>http://www.w3.org/2005/08/addressing/
>>>> anonymous</wsa:Address>
>>>>       </wse:NotifyTo>
>>>>     </wse:Delivery>
>>>>   </wse:Subscribe>
>>>> </s:Body>
>>>> </s:Envelope>
>>>> - gp
>>>> Yves Lafon wrote:
>>>>> On Tue, 7 Apr 2009, Gilbert Pilz wrote:
>>>>>> WS-Addressing 1.0 - Core defines two "special" URIs;
>>>>>> "http://www.w3.org/2005/08/addressing/anonymous"<http://www.w3.org/2005/08/addressing/anonymous> and
>>>>>> "http://www.w3.org/2005/08/addressing/none"<http://www.w3.org/2005/08/addressing/none>. Messages targeted
>>>>>> to either
>>>>>> of these URIs are processed differently from messages targeted to
>>>>>> "normal" URIs such as "http://webserivce.bea.com/. . ."<http://webserivce.bea.com/...>.
>>>>> Well, they are different, but unless you know WS-Addressing, or
>>>>> unless you resolve http://www.w3.org/2005/08/addressing/
>>>>> anonymous and find out the relationship between this URI and the
>>>>> WS-Addressing spec.
>>>>> If you resolve http://webservice.bea.com/... you will probably
>>>>> have information about the endpoint, or you may know it in
>>>>> advance from another document. So both URIs are opaque, unless
>>>>> you know their semantic.
>>> Take care:
>>>
>>>   Dr. David Snelling < David . Snelling . UK . Fujitsu . com >
>>>   Fujitsu Laboratories of Europe Limited
>>>   Hayes Park Central
>>>   Hayes End Road
>>>   Hayes, Middlesex  UB4 8FE
>>>   Reg. No. 4153469
>>>
>>>   +44-7590-293439 (Mobile)
>>> ______________________________________________________________________
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>>
>
> --
> Baroula que barouleras, au tiéu toujou t'entourneras.
>
>        ~~Yves
>
>
Received on Tuesday, 12 May 2009 23:14:31 GMT

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