Re: [sca-bindings] [Issue 2] Inlined proposal v2

[Mike Edwards <mike_edwards@uk.ibm.com>]

Folks,

I think that 2 optional conformance
points is desirable, as Anish discusses in the final paragraph of his note.

Yours,  Mike.

Strategist - Emerging Technologies, SCA & SDO.
Co Chair OASIS SCA Assembly TC.
IBM Hursley Park, Mail Point 146, Winchester, SO21 2JN, Great Britain.
Phone & FAX: +44-1962-818014    Mobile: +44-7802-467431  
Email:  mike_edwards@uk.ibm.com

From:	Anish Karmarkar <Anish.Karmarkar@oracle.com>
To:	Eric Johnson <eric@tibco.com>
Cc:	Simon Nash <oasis@cjnash.com>, OASIS Bindings <sca-bindings@lists.oasis-open.org>
Date:	14/05/2009 19:19
Subject:	Re: [sca-bindings] [Issue 2] Inlined proposal v2

---

Eric Johnson wrote:
> Hi Anish,
> 
> Anish Karmarkar wrote:
>> Simon Nash wrote:
>>> Anish,
>>> As currently written, the conformance section requires that
>>> implementations claiming support for the SCA Web Services
>>> Callback Protocol MUST support both the "regular"
flavor
>>> defined in section 5 and the WS-MC flavor defined in section
>>> 5.1.  I thought the intention was to give these two flavors
>>> equal status and allow implementations to support either or
>>> both of them.
>>>
>>
>> I had thought otherwise. I.e., a runtime is required to support
both. 
>> A particular service/composite gets to choose whether it wants
to use 
>> polling or host a listener. I don't feel strongly about this,
but we 
>> should discuss as to what we would like.
> I side with Simon here.  In the scenario where I support callbacks,
I 
> can have lots of reasons for not supporting callbacks via a polling
> mechanism.  To wit:
> 
>     * Security
>     * Latency
>     * Bandwidth consumption
> 
> There are other, far better ways to send messages asynchronously (JMS,
> SMTP, XMPP), and mandating that any implementation that supports the
> direct callback mechanism must also support the polling callback flies
> in the face of this simple technical observation.  Why would
we want to 
> mandate the use of an inferior approach?
> 

All of those actually are a form of polling as far as the client is 
concerned with a central server in between a la WS-Polling 
(http://www.w3.org/Submission/ws-polling/)
with the third party mailbox, 
just not polling as defined by this specific protocol. WS-Polling was a
precurser to WS-MC. But that is beside the point.

In any case, I did not intent to mean that this approach is mandated for
services that use bidirectional interfaces and binding.ws. If the words
don't say that then we need to fix it. But what I meant was that a 
*runtime* that claims conformance to this feature support it. As an 
assembler you get to choose which mechanism you want for a particular 
service which would be advertised via the WS-MC and SCA callback policy
assertions.

Do you think that there needs to be two optional conformance points for
runtimes? One for sca callback with listener and another for sca 
callback with ws-mc ?

-Anish
--


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