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Re: Intermediaries

From: Francis McCabe <fgm@fla.fujitsu.com>
Date: Fri, 5 Dec 2003 12:30:18 -0800
Message-Id: <D7915FBE-2761-11D8-B6CE-000A95DC494A@fla.fujitsu.com>
Cc: "<www-ws-arch@w3.org>" <www-ws-arch@w3.org>
To: "Ugo Corda" <UCorda@SeeBeyond.com>

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 15:30:39 GMT

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