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Re: Reference Parameters - using them

From: Pete Hendry <peter.hendry@capeclear.com>
Date: Fri, 30 Sep 2005 11:38:27 +1200
Message-ID: <433C7AF3.2090102@capeclear.com>
To: Marc Hadley <Marc.Hadley@Sun.COM>
CC: "Conor P. Cahill" <concahill@aol.com>, public-ws-addressing@w3.org

Is there a set of scenarios that the current ReferenceParameters 
actually addresses?

It is an option to point to WS-Context but the way I see it is that 
every man and his dog is going to implemetn WS-Addressing (or have done 
already) but WS-Context is a different matter. It is not such a high 
priority and so interoperability with it will be patchy for some time to 
come. The functionality I mention is an every day requirement and 
WS-Addressing had the ideal opportunity to provide a solution in a 
mechanism it provides. Without addressing this scenario 
ReferenceParameters become limited to a small niche of problems (very 
small in my opinion).

As Marc says, each implementation is going to come up with a proprietary 
mechanism to support the server sending dynamic reference parameters to 
the client and (the really proprietary part) the client using those 
parameters in the next request. Even if it is something as simple as the 
server adding a wsa:From EPR or even a wsa:ReplyTo and the client using 
the parameters in that. Even though this uses wsa headers, the 
interpretation by the client would be proprietary and not interoperable.

Even if it is a note I'd like to see this addressed somewhere and at the 
same time or soon after the WS-Addressing spec goes to final status. As 
I say, it is a problem WS-Addressing seems designed to solve and until I 
really started to use addressing I didn't realise what a hole this is.


Marc Hadley wrote:

> I agree that this is a missed opportunity. As is clear from Conor's  
> message, users of Addressing will end up designing multiple solutions  
> to the problem. As I suggested earlier, perhaps we need a more  
> visible pointer to WS-Context in the specification or, alternatively,  
> a WG note could specify a standard WS-Addr based mechanism ?
> Marc.
> On Sep 29, 2005, at 9:36 AM, Pete Hendry wrote:
>> Good to know I'm not the only one thinking this. The problem I see  
>> is the usefulness of AddressingParameters is seriously degraded in  
>> the current design. I see almost no useful scenarios for their use  
>> in their current state. I'm sure people can come up with plenty  that 
>> they may use them for, but as I said the most common case (I'd  go so 
>> far as to say that it is probably the main use I would have  for 
>> them) is not supported which is a big loss.
>> Pete
>> Marc Hadley wrote:
>>> On Sep 28, 2005, at 7:35 PM, Pete Hendry wrote:
>>>> Related to David's examples for i057, I was wondering about what  
>>>> I  would consider the most common use-case for reference  
>>>> parameters -  the server wanting the client to return context in  
>>>> the next  request. It seems to me the current design of reference  
>>>> parameters  are only useful for
>>>> a) fixed value data - i.e. not session-like data
>>>> b) the client asking the server to pass back information using  
>>>> the  replyTo header
>>>> Consider the (common?) scenario where a client logs into a  
>>>> server.  The server then creates a "session" in which it has  
>>>> customerKey and  shoppingCartId values it wants the client to  pass 
>>>> back in each  subsequent request. These are opaque as the  client 
>>>> does not have to  know what the customerId or  shoppingCartId are 
>>>> to work, it just has  to include them as-is.  ReferenceParameters 
>>>> seem the ideal vehicle  for this but where  would the server 
>>>> specify these parameters?
>>> This is the kind of use case I had in mind when I raised issue 15 
>>> [1],  the group didn't want to go there and we settled on pointing  
>>> to WS- Context instead[2]. Mebbe we need to add something to the   
>>> specification along these lines rather than just in the issue   
>>> resolution in the issues list ?
>>> Marc.
>>> [1] http://www.w3.org/2002/ws/addr/wd-issues/#i015
>>> [2] http://lists.w3.org/Archives/Public/public-ws-addressing/ 
>>> 2005Jan/ 0180
>>>> They are not fixed values and will change for each  "conversation"  
>>>> so they cannot just be specified in the WSDL with  fixed values.  
>>>> They have to be parameterized somehow to allow the  server to set  
>>>> the actual session values and pass them to the  client to be  
>>>> included in the next request.
>>>> Is this beyond the scope of reference parameters? In (my   
>>>> understanding of) their current form they are of little use. It  
>>>> is  unlikely you would want to publish fixed values within  
>>>> parameters  in WSDL (or any other static mechanism) and less  
>>>> likely that the  client would start the session information that  
>>>> could be contained  within them.
>>>> Pete
>>> ---
>>> Marc Hadley <marc.hadley at sun.com>
>>> Business Alliances, CTO Office, Sun Microsystems.
> ---
> Marc Hadley <marc.hadley at sun.com>
> Business Alliances, CTO Office, Sun Microsystems.
Received on Thursday, 29 September 2005 23:38:40 UTC

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