[ogsa-wg] FW: Issue #1 proposed resolution

[Steve Tuecke]

The difference the WS-A working group seems to be expousing between 
Reference Properties and Reference Parameters is that Reference 
Properties comprise part of the identity of the resource (along with 
the address), where as Reference Parameters do not constitute any part 
of the identity.  In other words, Reference Parameters are like cookies 
on the Web that are used to identify transient sessions, for example.

Given this viewpoint and the remove of Reference Properties, the 
"correct" place to push this information is into the Address, rather 
than the Reference Parameters.  But I agree that Reference Parameters 
could technically be used for what we are currently using Reference 
Properties.  In either case, the information still shows up in the SOAP 
header of the request message -- either in the wsa:To header, or in the 
Reference Parameters element.

Note that this who discussion does not suggest to me that we should 
move away from WS-A.  The reason I've always liked the move to WS-A was 
that it clearly defined how information from the EPR was required to 
show up in the SOAP header of a message -- the EPR address must be put 
in the wsa:To header, and the Reference Properties must be copied into 
the header.  This allows dispatch to be performed solely on the 
contents of the SOAP message.  Previously the address to which a 
message was being directed would only show up in the http post header 
of the message, which made message dispatch somewhat more complex.  So 
the practical ramification of this WS-A change on GT, for example, is 
simply that we get the service address and resource identifier from the 
wsa:To SOAP header, rather than from some other SOAP header that came 
from the Reference Properties.

-Steve

On Jan 22, 2005, at 6:47 AM, Tom Maguire wrote:

> I have to agree with Savas w.r.t. Reference Parameters.  The issue at 
> hand in the WS-A working
> group was the 'identity' semantic of Reference Properties vs URIs.  I 
> do not think that reference
> parameters will be removed from the spec and reference parameters can 
> be used for service-side
> dispatch.
>
> Tom
>
> Savas Parastatidis wrote:
>
>> Dear all,
>>
>> I agree with some of what Steve said bellow :-))
>>
>> The change does make a difference in implementations because if the
>> information that was meant to be included in the Reference Properties 
>> is
>> now encoded in the Address property of an EPR (the URI) it cannot be
>> echoed back as SOAP headers. This was part of the semantics of 
>> Reference
>> Properties.
>>
>> For a resource-oriented specification like WSRF, however, using URIs 
>> to
>> identify resources is a good solution. On this I agree with Steve. The
>> semantics of WSRF do not have to change even if it wasn't abstracted
>> away from WS-Addressing. What is lost is the ability to echo back as
>> SOAP headers any resource-specific information that may be required 
>> by a
>> SOAP intermediary to identify the targeted resource. If having SOAP
>> headers is a requirement, though, I don't see why Reference Parameters
>> couldn't be used.
>> So, while Reference Properties have been removed, Reference Parameters
>> are still there and while I would personally like to see them go too, 
>> I
>> don't think it'll happen. The semantics of Reference Parameters are
>> slightly different but I don't see why WSRF couldn't use them, if it
>> needed to, instead of Reference Properties to carry resource-specific
>> information.
>>
>> Best regards,
>> --
>> Savas Parastatidis
>> http://savas.parastatidis.name
>>
>>
>>> -----Original Message-----
>>> From: owner-ogsa-wg at ggf.org [mailto:owner-ogsa-wg at ggf.org] On Behalf
>>>
>> Of
>>
>>> Steve Tuecke
>>> Sent: Friday, January 21, 2005 9:55 PM
>>> To: Ian Foster
>>> Cc: 'Stephen Pickles'; 'OGSA-WG'; Steve Tuecke; Djaoui, A (Abdeslem)
>>> Subject: Re: [ogsa-wg] FW: Issue #1 proposed resolution
>>>
>>> As far as I can tell, this decision has basically no effect on WSRF.
>>> The argument being made by some in the WS-A working group is that it
>>>
>> is
>>
>>> equivalent and more true to the Web to carry a resource identifier as
>>> part of the EPR address, rather than in a separate ResourceProperties
>>> field -- that is, the resource reference should all be in the URI,
>>> rather than split between a URI and separate resource properties.
>>> Implementation-wise it certainly makes very little difference.  And
>>>
>> the
>>
>>> WSRF working group had already abstracted the WS-Resource reference
>>>
>> and
>>
>>> access pattern, so that it is not tightly coupled to WS-A and
>>>
>> reference
>>
>>> properties anyway, so WSRF specification-wise it makes no difference.
>>>
>>> -Steve
>>>
>>> On Jan 21, 2005, at 1:59 PM, Ian Foster wrote:
>>>
>>>
>>>> I think the technical term is "carefully architected set of
>>>> specifications" not "house of cards" (-:
>>>>
>>>> Regards -- Ian.
>>>>
>>>>
>>>> At 05:10 PM 1/21/2005 +0000, Djaoui, A (Abdeslem) wrote:
>>>>
>>>> Well, it probably doesn't, because WSRF is now decoupled from
>>>> WS-Addressing
>>>> through the definition of the "abstract" resource Access Pattern,
>>>> which
>>>> defines different embodiments for different ways of accessing
>>>>
>> state.
>>
>>>>
>>
>>
>>
>
>