Here are my immediate thoughts, in response, for the TC's consumption:
Michael Champion wrote:
Thank you for considering
Microsoft's suggestion for improving the SCA Web Services Binding
spec's interoperability (http://www.osoa.org/jira/browse/BINDINGS-87).
We suggested that Web
Services callbacks in the SCA Web Services Binging spec should
interoperate with comparable frameworks such as JAX-WS and WCF, and not
be limited to various implementations of SCA. This would promote the
original goals of the Web Services standards to achieve wire-level
interoperability among diverse run-times and platforms.
I'm unaware of anything in JAX-WS that addresses callbacks, so I don't
understand that point, or how it is comparable. Nor am I aware of
anything that we've specified that prevents a vendor from using JAX-WS
to implement callbacks support within the SCA environment. Presumably
implementation experience will reveal details here?
With respect to WCF, I'm not aware of its capabilities, and whether or
not it provides anything equivalent to the callback functionality of
SCA. Does anyone else on the TC have insight into this?
At the wire level, what we've describe remains interoperable and
compatible. Seems to me like the actual issue is at the protocol level.
The SCA Binding TC
responded by saying that the SCA Web Services binding protocol "defines
an *SCA* Web service callback protocol standard” and that it "is not
meant to satisfy general purpose callback requirements with a broadest
scope possible". In other works, the TC believes that the SCA Web
Services callbacks will NOT be interoperable with non-SCA
implementations
That sounds incorrect to me. Seems like it is completely out of scope
for an SCA TC to dictate how or if any standard outside of SCA reaches
compatibility with something inside of SCA. Nothing prevents other
implementations (Mike Champion's word choice) from achieving
interoperability.
The TC's response goes on
to say that "This TC does believe that it should define an
interoperable Web services protocol that implements SCA callback and it
has done that. It does not believe that it is in the scope or interest
of this TC to define a callback protocol for all architectures and
programming models." We respectfully find this statement contradictory,
unless the TC defines the term "interoperability" in its narrowest
form: SCA implementations will only be interoperable amongst
themselves, and not with other frameworks and runtimes. We would find
this unfortunate, as OASIS is committed to broad interoperability,
especially when it comes to use of Web Service wire protocols. It
would be better to standardize a Web Services callback in a separate
spec, with the participation of all vendors who build platforms and
products that support Web Services wire protocols.
Yes, we define interoperability amongst SCA runtimes (including from
different vendors), since that's within the scope of our charter. The
"narrowest" sense would be only interoperability among a single vendor
(see JMS itself, the "binding.sca" binding, and various Microsoft
networking protocols, at some point in time.). So I disagree with the
characterization of this as the "narrowest" possible form of
interoperability. Further, we don't deny the utility of a broad
specification, and yes, we believe interoperability at a larger scale
would be useful. It just isn't in our charter.
Is Microsoft explicitly requesting a change in charter? If so, they
should explicitly state that.
It is clear from [1]
that the TC is aware that interoperability with non-SCA runtimes is an
issue. The TC discussed the idea of moving the callback portion of the
protocol into its own document in order to address "the use case of
non-SCA clients does walk into the more general territory alluded to by
MS." We highly recommend that the Binding and Assembly TCs work
together to design a Web Services Binding spec that is interoperable
with non-SCA technologies. Without interoperability, software
developers and users will find it difficult to use SCA in the
heterogeneous, multi-vendor environments that all our customers live in.
Absolutely nothing here prevents vendors from building compatible
systems with both SCA and non-SCA parts that interact. In fact, we
expect it. Further, when bridging from a non-SCA environment to an SCA
environment, a vendor such as Microsoft should only have to implement
compatibility with the SCA WS Callbacks mechanism once, and it should
work with all vendors providing SCA environments. If they believe this
last point is incorrect, it would be enormously useful for Microsoft to
identify the specific oversights of the currently specified approach.
-Eric.
[1]
http://www.oasis-open.org/committees/download.php/34064/SCA%20Bindings%20minutes%202009-09-03.doc
Regards,
Michael
Champion
From: Simon
Holdsworth [mailto:simon_holdsworth@uk.ibm.com]
Sent: Thursday, September 17, 2009 7:04 AM
To: sca-bindings-comment@lists.oasis-open.org
Subject: [sca-bindings-comment] Response to: "Microsoft
technical comment: Develop interoperable approach notspecific to SCA
for callbacks"
This
is a formal response of the OASIS SCA Bindings technical committee to
the "Microsoft technical comment: Develop interoperable approach not
specific to SCA for callbacks" which was sent to the SCA Bindings
public comments list.
This is the agreed response of the technical committee as a whole and
was approved unanimously at the meeting of the TC
which took place on September 3rd 2009.
------------------------
Thanks
for taking the time to review the specification, sending your public
review comment [1], and for sharing you thoughts. They are much
appreciated.
The
public review comment at [1] suggests that: "... the work of defining a
Web Service callback standard is best done by the appropriate Web
Services working groups in OASIS in the broadest scope possible. This
will foster a general interoperable mechanism for all architectures and
programming models that use standard Web Services protocols on the
wire."
There
is a misunderstanding on the commenter's part that the SCA Web Services
Binding defines a (generally applicable) "Web Service callback
standard." The binding defines an *SCA* Web service callback protocol
standard that provides the wire-level details for implementing an SCA
callback defined by the SCA Assembly specification [2]. [2] defines a
callback mechanism that satisfies the needs of the SCA Assembly model
and is not meant to satisfy general purpose callback requirements with
a broadest scope possible. Furthermore, there does not exist any other
OASIS Web Services Working Group or a Technical Committee that
specializes in Web Services that has callbacks in its charter scope.
This TC *does* specialize in Web services and is chartered to produce a
Web services binding for SCA.
This
TC does believe that it should define an interoperable Web services
protocol that implements SCA callback and it has done that. It does not
believe that it is in the scope or interest of this TC to define a
callback protocol for all architectures and programming models.
WRT
your comment about SCA Assembly specification Section 7.4, we
respectfully request you to share that feedback with the SCA Assembly
TC [3], as the SCA Assembly specification is not owned by and is not in
scope for this TC.
[1]
http://lists.oasis-open.org/archives/sca-bindings-comment/200908/msg00000.html
[2]
http://docs.oasis-open.org/opencsa/sca-assembly/sca-assembly-1.1-spec-cd03.pdf
[3]
http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=sca-assembly
--------------------------
Follow-up comments are welcome.
Regards,
Simon
Simon Holdsworth
STSM, SCA Bindings Architect; Master Inventor; OASIS SCA Bindings TC
Chair
MP 211, IBM UK Labs, Hursley Park, Winchester SO21 2JN, UK
Tel +44-1962-815059 (Internal 245059) Fax +44-1962-816898
Internet - Simon_Holdsworth@uk.ibm.com
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