Re: [sca-bindings] ISSUE 2 - Callback support over the Web Servicebinding

[Anish Karmarkar <Anish.Karmarkar@oracle.com>]

I think this is a separate issue.

Given that callback information/addresses are binding dependent (or at 
least relegated to the binding), I don't see how this could work, in 
general. My initial reaction is to say that we should not allow it.

-Anish
--

Peshev, Peter wrote:
> Hi
> 
> When speaking about redirecting the callback, by API it is possible to
> redirect it to another component, whose services could be lacking
> binding.ws and instead having only some other binding /*let's say
> binding.jms due to the current lack of other bindings in the OASIS TC :)
> */. 
> 
> If that should be a supported scenario (outbound one binding, inbound
> another) that looks that the callbackId-s should be something SCA
> specific, and hardly rely on some WS-standard. I am little bit confused
> in which TC (java, assembly, bindings) that should be addressed.
> 
> Any thoughts / comments? 
> 
> Btw, I personally dislike refirecting the callback since that is
> actually dynamic appearance of wires (invocation paths) via java code
> usage. 
> 
> That introduces hidden dependencies among components, which cannot be
> analyzed and displayed by any tooling (except some heuristic code
> parsing), cannot be overridden by the assembler via SCDL files and
> somewhat hinders the main focus of component reuse and SOA. In addition
> such dynamic redirecting is likely to complicate any implementation
> which spans beyond one JVM.
> 
> 
> Best Regards
> Peter
> 
> 
> -----Original Message-----
> From: Simon Nash [mailto:NASH@uk.ibm.com] 
> Sent: Tuesday, 2. October 2007 13:51
> To: sca-bindings@lists.oasis-open.org
> Subject: Re: [sca-bindings] ISSUE 2 - Callback support over the Web
> Service binding
> 
> Using the wsa:ReplyTo header for the callback endpoint does not seem to 
> exactly match SCA callback semantics, which allow callback messages to
> be 
> directed to a different endpoint from the endpoint that receives the
> reply 
> to the original request (by calling setCallbackObject() with a 
> ServiceReference).  Using wsa:ReplyTo also requires a message ID to be 
> added to the original request and the same message ID to be returned on 
> the reply and any callbacks in the wsa:RelatesTo header.  This is more
> of 
> an observation than a problem, though it does require extra state to be 
> maintained for the message IDs being exchanged.
> 
> In Tuscany, we did not use wsa:Reply To.  Instead we used the 
> WS-Addressing wsa:To endpoint reference with reference parameters to 
> represent the callback endpoint (as a wsa:EndpointReference), the
> callback 
> ID, and the conversation ID for stateful callbacks.
> 
> I did not propose a specific solution when opening this issue because I 
> wanted to open this up to as many suggestions and options as possible.
> The 
> discussion around wsa:ReplyTo has been interesting.  Perhaps someone
> will 
> have an idea on we can overcome the semantic mismatch that I mentioned 
> above.  I agree that defining a new header for SCA callbacks would be 
> undesirable.  Even the use of SCA-specific reference parameters seems
> less 
> than ideal, but without them I'm not sure how additional information
> like 
> the callback ID could be transmitted.  We can't use wsa:MessageID for 
> this, because of the statement in the WS-Addressing spec that "No two 
> messages with a distinct application intent may share a [message id] 
> property."  Perhaps the callback ID could be mapped into a wsa:MessageID
> 
> by adding a unique discriminator, so different callback requests could
> use 
> distinct message IDs from which the same callback ID could be extracted.
> 
>     Simon
> 
> Simon C. Nash, IBM Distinguished Engineer
> Member of the IBM Academy of Technology
> Tel. +44-1962-815156  Fax +44-1962-818999
> 
> 
> 
> Khanderao Kand <khanderao.kand@oracle.com> 
> 01/10/2007 22:47
> 
> To
> Michael Rowley <mrowley@bea.com>
> cc
> sca-bindings@lists.oasis-open.org
> Subject
> Re: [sca-bindings] ISSUE 2 - Callback support over the Web Service
> binding
> 
> 
> 
> 
> 
> 
> Michael Rowley wrote:
>> One problem with using WS-Addressing wsa:ReplyTo is that it is usually
>> used to send the response message of a request/response pair.  I don't
>> think that WS-Address forbids its use for subsequent messages
>> (callbacks), but it would at least be unconventional.
>>
> [khanderao] IMHO WS-Addressing does not make any assumptions on the 
> number of returned messages. It is upto the integration scenario to have
> 
> one or many.
>> However, if we can't use wsa:ReplyTo, that would seem to imply that we
>> have to devise our own header to use, but that would be getting
>> dangerously close to inventing a wire-level protocol, which we don't
>> want to be doing.
>>
> [khanderao] Introducing SCA specific correlation / replyTo parameters 
> would not be essential. As far as possible we should be using the 
> available standards,  like WSA / WS-Coordination etc..
>> Michael
>>
>> -----Original Message-----
>> From: Eric Johnson [mailto:eric@tibco.com] 
>> Sent: Monday, October 01, 2007 12:16 PM
>> To: sca-bindings@lists.oasis-open.org
>> Subject: Re: [sca-bindings] NEW ISSUE: Callback support over the Web
>> Service binding
>>
>> Created as: http://www.osoa.org/jira/browse/BINDINGS-2
>>
>> -Eric.
>>
>> Simon Nash wrote:
>>
>>> TARGET:
>>>
>>> Web Service Binding specification, section TBD
>>>
>>> DESCRIPTION:
>>>
>>> The Web Service binding provides no example or suggestion for how SCA
> 
>>> callback semantics could be carried over Web services.  There is an 
>>> example in section 2.2.3 for how conversation semantics could be 
>>> supported.  It would be good to give some guidance (somewhere in the
>>>
>> range 
>>
>>> between example and normative) for what could be done for callbacks.
>>>
>> One 
>>
>>> possibility is to make use of the capabilities provided by
>>>
>> WS-Addressing.
>>
>>> PROPOSAL:
>>>
>>> None yet.
>>>
>>>
>>>
>>>
>>>
>>>
>>> Unless stated otherwise above:
>>> IBM United Kingdom Limited - Registered in England and Wales with
>>>
>> number 
>>
>>> 741598. 
>>> Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire
> PO6
>> 3AU
>>
>>>
>>>
>>>
>>>
>>>
> 
> 
> 
> 
> 
> 
> 
> 
> Unless stated otherwise above:
> IBM United Kingdom Limited - Registered in England and Wales with number
> 
> 741598. 
> Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6
> 3AU
> 
> 
> 
> 
> 
>