Title: [soa-rm] Sub Comittee and/or User guide
Duane,
Respectfully,
I wonder if we’re splitting hairs here. IMHO, many would consider “reference
model” and “reference architecture” to be synonymous. If they are not, it begs
the question: How many steps does one *really* need to go through to finally
implement a service-oriented architecture? Are we really making this easier for
the world, or more difficult? I say the latter.
For
this reason, I (as only one member of this TC) would not support the notion of a
new SC to tackle a more useful and actionable product than the one it seems we
are heading toward. I would recommend that we revisit our interpretation of the
definition of “reference model”, and – if necessary – call a vote to determine
what the TC members really believe the end product of this TC should be. My
concern is that this is becoming more of an academic exercise than a practical
one (but I would very much like to be proven wrong).
Some
(hopefully) supporting points:
-
The
description of this TC on the OASIS site is: “Developing
a core reference model to guide and foster the creation of specific,
service-oriented architectures”. According to how abstract our reference model
is turning out to be, I don’t believe that we are fulfilling that description
(“guide and foster”)
-
Here is
the definition of Reference Model in our charter, reproduced here for emphasis:
“Reference Model - A
reference model is an abstract framework for understanding significant
relationships among the entities of some environment, and for the development of
consistent standards or specifications supporting that environment. A reference
model is based on a small number of unifying concepts and may be used as a basis
for education and explaining standards to a non-specialist.”
IMHO, I for one do not believe that
including the concepts of “service consumer” and “service producer” would
violate this definition – however, I do recognize that the definition is
subjective.
-
I’ve
searched the Web for some reference models that exist – here are some, along
with my comments :
(1)
NASA
CCSDS Reference Model for an Open Archival Information System (OAIS): http://www.ccsds.org/documents/650x0b1.pdf
-
From
p.10: This reference model:
o
provides a
framework for the understanding and increased awareness of
archival concepts needed for Long Term digital information preservation
and access;
o
provides the concepts needed by
non-archival
organizations to be
effective
participants in the preservation
process;
o
provides a
framework, including terminology and concepts, for describing and comparing architectures and
operations of existing and future archives;
o
[etc.]
-
Note
second bullet above “provides the concepts needed”.
-
Also,
from p.30: See Figure 2-4: IMO, this figure provides enough details to make the
reference model useful and actionable.
(2)
WfMC
Workflow Reference Model:
http://www.wfmc.org/standards/model.htm
-
This
figure includes components such as: Workflow Client Application, Invoked
Applications, Process Definition etc. According to what I’ve been hearing up to
now by some, these would be “too concrete”. Please clarify then if you believe
this WfMC model is in your opinion truly a reference model. IMHO, it seems to be
highly useful and actionable.
(3)
Also the
OSI Model: I know that we’ve been making repeated references to this model
(pardon the pun), but many people do believe that the OSI model failed and
TCP/IP triumphed (not sure if that changes our perspective). Also, I don’t
believe that the OSI model was intended for the same type of purpose as we are
intending here. The OSI model’s mission was quite narrowly scoped, while ours –
by virtue of the fact that we are about service-oriented architecture – is much
broader. Different treatments for different missions
So in summary, I would very much
like us to consider loosening the constraints on our reference model just a bit,
to be able to include (or at least consider at length) useful components such as
security, orchestration, messaging, etc. Let's make our product (a) useful and
(b) actionable.
My $0.02 :)
Joe
From: Duane Nickull
[mailto:]
Sent: Mon 4/18/2005 5:23 PM
To:
SOA-RM
Subject: [soa-rm] Sub Comittee and/or User
guide
All:
I have read through the last batch of email.
There are a couple of
things I would like to propose for comments. Please
read this entire
email before replying.
1. I will concede that many
members of the public will likely have the
same kinds of trouble interpreting
a reference model vs. a reference
architecture vs a specific architecture as
seems to be pervasive on this
list. If we have the problem in our
context, it is likely to be present
outside of this list.
2. We cannot
redefine what a "reference model" is or what it includes.
If we tried
to change the industry definition of reference model to one
that has concrete
items in it or things that are not part of SOA (which
is tricky since it is
still undefined), it will not be a true reference
model and hence not
accepted by industry.
3. Service provider and service consumer are not
part of a reference
model. They are roles visible only in a runtime or
infrastructure views
of a specific architecture. To prove this point,
please look once again
at the OSI reference model. It is a
communications stack RM yet does
not contain notions of a message sender and
message receiver.
4. We cannot mix abstract concepts and "things people
can chew on"
(implying concrete items) in our work. Such does run
adverse to
accepted architectural conventions.
SOLUTION:
One
way forward is to probably create a sub committee to work on a
reference
architecture for SOA. A Reference Architecture could be
developed in
parallel to the reference model and is fair game to
illustrate things like
security, consumers, providers, agents etc. It
is within our charter to
do such.
After reading through some older emails, I would assert that
such a
thing is probably essential along with some sort of white paper
or user
guide that explains the relationships between the RM, the RA and
other
architecture.
Reference Model
(is a guide for developing
a)
[ Reference Architecture || * Architecture ]
There are several
people on this list who also have stated specific
needs for what they see in
SOA. Perhaps this may be a good Sub
Committee (SC) consideration
also.
Government Service Oriented Reference
Architecture???
etc.
I can already see there are many of you who could
lead such an effort as
a sub
committee.
Comments?
Duane
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***********
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Standards Strategist - Adobe Systems, Inc. - http://www.adobe.com
Vice Chair - UN/CEFACT
Bureau Plenary - http://www.unece.org/cefact/
Adobe
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