Re: [sca-bindings] [Issue 2] Proposal version 3: How to implement SCAcallbacks using SOAP

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

Tom,

The question worth asking here is how
you can draw up this material to be optional and yet normative.

How do you bound the optionality?  There
might be quite a number of ways in which you could create a
binding based on web services functionality
that implements SCA callback capability.  We don't want to
outlaw those, while it is useful to
encourage use of a straightforward and generally implemented set
of capabilities such as are represented
by Anish's proposal below.

I suppose that an SCA runtime can claim
to conform to the scheme defined in Anish's proposal and what
that would amount to is that the runtime
would have to pass some set of conformance tests that are built 
based on that proposal.  Being
normative at least allows the test(s) to be part of the overall SCA test
suite,
even if conforming to those tests is
purely optional.

What I am wary of doing is preventing
other ways of using the web services specifications/standards to 
implement SCA capabilities such as callbacks.
 Such alternatives should be possible and perfectly valid.


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:	Tom Rutt <tom@coastin.com>
To:	Mike Edwards/UK/IBM@IBMGB
Cc:	OASIS Bindings <sca-bindings@lists.oasis-open.org>
Date:	03/11/2008 20:35
Subject:	Re: [sca-bindings] [Issue 2] Proposal version 3: How to implement SCA callbacks using SOAP

---

Mike Edwards wrote:
>
> Folks,
>
> I believe that what we previously decided regarding these descriptions
> of how to implement specific
> capabilities of SCA using a given binding is that they would form
> non-normative examples in an
> appendix in the relevant bindings specification.
I cannot see how Anish's proposal for implementing SCA callbacks using
Soap and Ws Addressing
can work if it is only a non-normative example.

The proposal includes the following text:
"
The wsa:RelatesTo SOAP header block MUST have the relationship type 
value of "http://docs.oasis-open.org/opencsa/sca-bindings/ws/callback"
and the related message id is the wsa:MessageID of the message from 
which the Callback EPR was obtained.
"

This text registers a special value to use within the wsa:relatesTo 
element.   To Register this
special value requires it to be included in a normative part of the spec.

I like Anish's proposal, and do not see another way to do it with ws 
addresssing in use.

I think a better Idea is to have the text be in a normative part of the
spec, but be considered an
optional compliance point which can be asserted by an implementation,
when sca is bound to wsdl/soap with ws addressing in this manner.

Tom Rutt
>
> So, the idea is that a proposal like Anish's would be ONE way of doing
> callbacks with SCA over web
> services (SOAP), but would not rule out other ways of doing it.  What
> it would show is that:
>
> a) there IS a way to implement the callback capability over web services
>
> b) the example will encourage implementers to provide callback in
this 
> way and if so, then it would give
> a way to improve interoperability - if both ends implement according
> to the example, they should interoperate.
>
>
> As for the @callback annotation for WSDL - the main purpose is for
SCA 
> usage (to provide the same capability
> that we have in Java interfaces with the @callback annotation) - but
> of course if a WSDL with such an annotation
> is encountered by a non-SCA web services client, that client can 
> choose to interpret it in the way that SCA defines....
>
> 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:                
 OASIS Bindings <sca-bindings@lists.oasis-open.org>
> Date:                
 29/10/2008 23:58
> Subject:              
   Re: [sca-bindings] [Issue 2] Proposal version 3: How
to 
> implement SCA callbacks using SOAP
>
>
> ------------------------------------------------------------------------
>
>
>
> I forgot to mention that when this proposal is combined with Mike's
idea
> of defining a WSDL extension to indicate the callback interface (similar
> to the @Callback Java annotation), what we have is a WS-Callback
> specification (I know, yet another WS-Splat spec). Such a spec could
be
> a stand-alone spec independent of SCA and would result in non-SCA
> systems being able to talk to SCA services that offer bi-directional
> interfaces.
>
> -Anish
> --
>
> Anish Karmarkar wrote:
> > Attached.
> > I have converted the HTML version to Word, so that it is easy
for folks
> > to comment and make inline changes.
> >
> > The big change between v2 and v3 is the addition of faults. My
initial
> > inclination was to define our own faults, but it turns out 
> WS-Addressing
> > has some pre-defined faults which fit our purpose. So, I have
reused
> > those faults.
> >
> > One thing I'm not clear on is whether the TC wishes to define
this
> > SOAP-specific callback mechanism as *one* of the ways callbacks
can be
> > implemented when using SOAP or *the* way callbacks are implemented
when
> > using SOAP. My inclination is to say *the* way, otherwise we
have to
> > invent ways (metadata such as policySets, ws-policy assertion,
WSDL
> > extension, Java annotation) to convey when it is required.
> >
> > Comments?
> >
> > -Anish
> > --
> >
> >
> > ------------------------------------------------------------------------
> >
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-- 
----------------------------------------------------
Tom Rutt                
email: tom@coastin.com; trutt@us.fujitsu.com
Tel: +1 732 801 5744          Fax: +1 732 774
5133



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