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Re: Intermediaries

From: Francis McCabe <fgm@fla.fujitsu.com>
Date: Fri, 5 Dec 2003 12:57:22 -0800
Message-Id: <9F521010-2765-11D8-B6CE-000A95DC494A@fla.fujitsu.com>
Cc: "Ugo Corda" <UCorda@SeeBeyond.com>, www-ws-arch@w3.org
To: "Cutler, Roger (RogerCutler)" <RogerCutler@chevrontexaco.com>

Oh yes, I agree with that.
However, the problems of building large scale systems are not going to 
disappear with the working group! So, I am not arguing for actually 
solving these issues; but I am trying to put things into their proper 
context.

It would be easy to simply discard intermediaries. After all, WSDL has! 
(And so, I believe, has WS-I)

In any case, I am not really raising problems. There *are* problems 
with the picture around intermediaries (and a few other places too :) I 
think that putting them into a proper context will allow us to decide 
whether to ignore them, raise their profile, whatever.

Frank

On Dec 5, 2003, at 12:37 PM, Cutler, Roger (RogerCutler) wrote:

> Yes -- is it possible that the issues that you are trying to raise with
> respect to intermediaries are beyond a reasonable scope for the present
> effort, given the practical limitations of time and personnel?
>
> -----Original Message-----
> From: www-ws-arch-request@w3.org [mailto:www-ws-arch-request@w3.org] On
> Behalf Of Ugo Corda
> Sent: Friday, December 05, 2003 2:34 PM
> To: Francis McCabe
> Cc: www-ws-arch@w3.org
> Subject: RE: Intermediaries
>
>
>
> Frank,
> I doubt we are going to solve that problem in the little more than a
> month left ...
>
> Ugo
>
>> -----Original Message-----
>> From: Francis McCabe [mailto:fgm@fla.fujitsu.com]
>> Sent: Friday, December 05, 2003 12:30 PM
>> To: Ugo Corda
>> Cc: <www-ws-arch@w3.org>
>> Subject: Re: Intermediaries
>>
>>
>> I kind of take a mild exception to this Ugo. I don't think it is fair
>> to say that I am try to "satisfy my philosophical interests" with
>> computer technologies.
>>
>> I am banging on quite a lot about intermediaries because I think that
>> it represents a way into a very difficult problem: how to actually
>> build large scale systems.
>>
>> Frank
>>
>>
>> On Dec 5, 2003, at 12:16 PM, Ugo Corda wrote:
>>
>>>
>>> Roger,
>>>
>>> I would not go for the deep philosophical meaning in all
>> this. We just
>>> have to acknowledge that specs have always some
>> underspecified areas.
>>> Maybe when WS-I decides to tackle intermediaries in a Basic Profile
>>> (right now they are just "extension points"), it will pick a
>>> particular interpretation of this subject and run with it.
>>>
>>> In my view, computer technologies are not the right place
>> to look when
>>> you want to satisfy your philosophical interests ;-).
>>>
>>> Ugo
>>>
>>>> -----Original Message-----
>>>> From: www-ws-arch-request@w3.org
>> [mailto:www-ws-arch-request@w3.org]On
>>>> Behalf Of Cutler, Roger (RogerCutler)
>>>> Sent: Friday, December 05, 2003 11:59 AM
>>>> To: Ricky Ho; www-ws-arch@w3.org
>>>> Subject: RE: Intermediaries
>>>>
>>>>
>>>>
>>>> I might also comment that Frank seems to have a more
>> Olympian view of
>>>> the matter and, as far as I can tell, is saying that the
>> messages are
>>>> "the same" because we DEFINE them to be the same, not
>> because they are
>>>> judgeed to be the same by any criteria.  Maybe I didn't
>> put this quite
>>>> right because I don't understand what he is saying, so I didn't
>>>> make an effort to capture it.
>>>>
>>>> -----Original Message-----
>>>> From: www-ws-arch-request@w3.org
>>>> [mailto:www-ws-arch-request@w3.org] On Behalf Of Cutler, Roger
>>>> (RogerCutler)
>>>> Sent: Friday, December 05, 2003 1:53 PM
>>>> To: Ricky Ho; www-ws-arch@w3.org
>>>> Subject: RE: Intermediaries
>>>>
>>>>
>>>>
>>>> Again, this is sort of third hand -- I have been trying to capture
>>>> what other people said.  However, I believe that the sense I
>> got from David
>>>> Booth and others is that the issue of whether the message
>> going from A
>>>> to I is "the same" as that going from I to B is something that has
>>>> to be considered in the context of "the application", broadly
>>>> understood. That
>>>> is, "the application" includes both what A is doing and what
>>>> B is doing.
>>>> So I guess that there is a God-like observer involved in
>> this scenario
>>>> or something.  I don't see how you can think about choreography
>>>> without postulating some observer that can see everything that
>>>> happens and whose
>>>> observations correspond absolute reality, as opposed to what
>>>> is visible
>>>> to any particular participant.
>>>>
>>>> -----Original Message-----
>>>> From: Ricky Ho [mailto:riho@cisco.com]
>>>> Sent: Friday, December 05, 2003 1:30 PM
>>>> To: Cutler, Roger (RogerCutler); www-ws-arch@w3.org
>>>> Subject: RE: Intermediaries
>>>>
>>>>
>>>> 1) I can't see how B or C can determine whether the modified
>>>> message is the
>>>> same message given that they haven't seen the original one.
>>>>
>>>> 2) SOAP doesn't have the "SAME MESSAGE" concept and therefore it is
>
>>>> NOT possible to make such differentiation at the SOAP level.  In
>>>> some other
>>>> spec (such as RM), the "SAME MESSAGE" concept is very
>> important, there
>>>> they
>>>> define the messageID explicitly.
>>>>
>>>> About your encryption scenario, if determining the "SAME
>> MESSAGE" is
>>>> important to me, then I have to decrypt the messageID.  And if I
>>>> cannot decrypt it, I shouldn't process the message.
>>>>
>>>> Rgds, Ricky
>>>>
>>>> At 12:45 PM 12/5/2003 -0600, Cutler, Roger (RogerCutler) wrote:
>>>>> I'm not an expert here, and I was mostly trying to capture
>>>> the sense of
>>>>
>>>>> a conversation.  However, I believe that several people
>>>> agreed that it
>>>>> is, indeed, up to B and C to participate in this decision,
>>>> and that the
>>>>
>>>>> "application" envisaged includes both sender and
>> receiver.  This was
>>>>> explicitly stated, I believe, by both David Booth and at least one
>
>>>>> other person, I've forgotten whom.
>>>>>
>>>>> About the messageID -- does a SOAP message necessarily
>> have one?  If
>>>>> the intermediary encrypts the message, including the ID,
>> do you have
>>>>> the same messageID?  It seems to me, from listening and
>>>> participating
>>>>> in a certain amount of conversation trying to sharpen up the
>>>> concept of
>>>>
>>>>> "same message" that this is a swamp.
>>>>>
>>>>> -----Original Message-----
>>>>> From: Ricky Ho [mailto:riho@cisco.com]
>>>>> Sent: Friday, December 05, 2003 10:49 AM
>>>>> To: Cutler, Roger (RogerCutler); www-ws-arch@w3.org
>>>>> Subject: Re: Intermediaries
>>>>>
>>>>>
>>>>> Can we use messageID to determine whether this is the "SAME"
>>>> message ?
>>>>> In other words, all other modification is insignificant.
>>>>>
>>>>> 1) Intermediary isn't the endpoint so it doesn't generate
>>>> new messages,
>>>>
>>>>> so the message it send MUST have same messageID as some previous
>>>>> messages it received.
>>>>> 2) Orchestration is the endpoint which produce or consume
>>>> messages, so
>>>>> the
>>>>> message it send MUST have different messageID from
>> previous received
>>>>> messages
>>>>>
>>>>> Going back to your example, it is NOT up the B and C to
>>>> interprete the
>>>>> changes made by I differently.  The decision is completely
>>>> finalized by
>>>>
>>>>> I.
>>>>>
>>>>> Best regards,
>>>>> Ricky
>>>>>
>>>>> At 09:44 AM 12/5/2003 -0600, Cutler, Roger (RogerCutler) wrote:
>>>>>
>>>>>> Here is some text that expresses my understanding of the sense of
>
>>>>>> some of the telcon conversation about intermediaries.
>> Please use,
>>>>>> modify or
>>>>>
>>>>>> ignor as seems appropriate.
>>>>>>
>>>>>> It is useful to draw a distinction between situations
>>>> where messages
>>>>>> are passed through intermediaries and choreographies.  The
>>>> essential
>>>>>> issue is that an intermediary passes along a message that is
>>>>>> essentially, or functionally, the same as it received.
>> If, on the
>>>>>> other hand, the purpose or function of the message is
>>>> substantially
>>>>>> changed one should consider the situation to be a
>>>> choreography.  This
>>>>
>>>>>> cannot be defined, however, in an entirely rigorous or black and
>>>>>> white way -- one person's intermediary may legitimately be
>>>> considered
>>>>
>>>>>> a choreography by others. Note that since an intermediary
>>>> can change
>>>>>> the message, for example by encrypting it or by adding ancillary
>>>>>> information, it remains a judgment call whether those changes are
>
>>>>>> significant and functional.  In addition, whether a service that
>>>>>> passes
>>>>>
>>>>>> messages is considered an intermediary depends on
>>>> participants in the
>>>>
>>>>>> entire chain of the message.  For example, if sender A
>>>> sends messages
>>>>
>>>>>> through I, which modifies the messages, to receivers B and
>>>> C, B might
>>>>
>>>>>> consider the modified message to be functionally unchanged
>>>> whereas C
>>>>>> might consider it to be different and take different
>>>> action because
>>>>>> of the modification.  In the first case I would be considered an
>>>>>> intermediary, in the second it would not.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>
>>
>
>
>
Received on Friday, 5 December 2003 16:07:07 GMT

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