A few
contextual comments and questions inline. I typed these originally on Friday night before
the thread of conversation spun out with some other members of the SOA-RM on
this mailing list. However, I think my comments below still
apply.
Rebekah
Rebekah
Metz
Associate
Booz Allen
Hamilton
Voice:
(703) 377-1471
Fax:
(703) 902-3457
-----Original
Message-----
From: soa-forum-bounces@xxxxxxxxxxxxxx [mailto:soa-forum-bounces@xxxxxxxxxxxxxx]
On Behalf Of Andras Szakal
Sent: Friday, May 05, 2006 9:50 AM
To: Chris
Harding
Cc: Service-Oriented Architecture CoP; soa@xxxxxxxxxxxxx
Subject: [soa-forum]
Re: Definitions of SOA
Team,
I offer this
additional chart which depicts the outcome of our
discussion
last week. I am
still working the chart but it's a decent start. We
agreed
that SOA is
actually only one aspect of this very interesting
industry
initiative that
needs our focus.
<RLM>
Although I like the concepts that you’ve related to the notion of services and
SOA, I have a concern that SOA seems to be considered only as a technology layer
concept of a larger concept called SOA. I would challenge the group to
realize instead that SOA is about the alignment of IT with business.
Intuitively, this concept spans the three layers in the first slide.
As part of
the SOA RM out of OASIS, we initially started down this same path. In
fact, during early drafts of the RM, several members of the TC contemplated
renaming the specification to “Service Reference Model.” In addition, we
spent a significant amount of time working to a description of SOA that spans
these three layers presented - because they are synergistic. (Note that
within the reference model we don’t directly discuss technologies which are left
for Reference Architectures and Implementations).
I think we need
to focus on service orientation as a superset of the
SOA
discussion. In
fact one could argue that service orientation may
be
implemented by
a combination of architectural styles and not just
SOA/web
services.
I’d be
interested in hearing about what other architectural styles fit the
bill.
(See attached
file: Service_Orientation_Def_v1.ppt)
<Stepping onto my
soapbox>
The notion
that a service is a “thing” which is separate from a capability that is served
is incorrect. A service is an event. It is not separate from a
capability. It is the performance of that capability by some entity
(service provider) for some other entity (service consumer). Although it
is easy to think about the concept of service in terms of
‘things’; in actuality, this
concept unifies both active and thing. In the same vein, it is a red
herring to think about SOA as technology only.
In
Slide #2, the discussion of service orientation maps nicely to the treatment of
needs and capabilities as part of the SOA Reference Model. The difference
is that this definition seems to treat service orientation separately from the
core definition of SOA. Instead, brining together needs and capabilities
is of the essence in SOA, an integral part.
The
definition of service speaks of a black box. With this definition, I would
ask what is the role of a service description? Does the existence of a
service interface, and the inputs/outputs with which service interactions occur
part of the black box?
I don’t understand
why the final two bullets, namely “Requires strong governance of service
representation and implementation” and “Requires a ‘Litmus Test’, which
determined a ‘good services’ are part of the definition? Who decides
“good” vs. “bad” services?
Rebekah
Regards,
Andras
Andras Robert
Szakal
Chief Architect
IBM Federal Software Group
Distinguished
Engineer & Senior Certified IT
Architect
Member Open
Group Board of Directors
Tie Line:
930-9215
External Line:
202-595-1678
text message:
andras1@xxxxxxxxx
email: aszakal@xxxxxxxxxx
Chris
Harding
<c.harding@opengr
oup.org>
To
Service-Oriented
Architecture CoP
05/05/2006 08:31 <soa-forum@xxxxxxxxxxxxxx>,
AM
"'Service-Oriented Architecture
CoP'" <soa-forum@xxxxxxxxxxxxxx>
cc
soa@xxxxxxxxxxxxx
Subject
Definitions
of
SOA
Hi
-
As a further
update, here is the definition of SOA that was presented
at
The Open Group
conference last week (and which we have shared with
the
OMG).
SOA is an
architectural style that supports service
orientation
•Service
orientation
A way of a way
of thinking in terms of services and service
based
development and
the outcomes that services bring
•Service
A logical
representation of a repeatable business activity that has
a
specified
outcome (e.g., check customer credit; provide weather
data,
consolidate
drilling reports), is self-contained and maybe composed
of
other Services.
It is a black box to consumers of the
Service
•Architectural
Style
The combination
of distinctive features in which Enterprise Architecture
is
done, or
expressed
•The SOA
Architectural style’s distinctive
features:
– Based
on the design of the services comprising an
enterprise’s
(or
inter-enterprise) business processes. Services mirror
real-world
business activity
–
Service representation utilizes business descriptions.
Service
representation requires providing its context (including
business
process, goal, rule, policy, service interface and service
component)
and
service orchestration to implement
service
– Has
unique requirements on infrastructure. Implementations
are
recommended to use open standards, realize interoperability
and
location transparency.
–
Implementations are environment specific, they are constrained
or
enabled
by context and must be described within their
context.
–
Requires strong governance of service representation and
implementation
–
Requires a “Litmus Test", which determined a “good
service”
At 20:31
04/05/2006, Cory Casanave wrote:
As an update from the OMG meeting last week, the SOA SIG adopted
the
following definition of SOA;
Service Oriented Architecture is an architectural style for
a
community of providers and consumers of services to achieve
mutual
value, that:
Allows participants in the communities to work together
with
minimal co-dependence or technology
dependence
Specifies the contracts to which organizations, people
and
technologies must adhere in order to participate in
the
community
Provides for business value and business processes to
be
realized by the community
Allows for a variety of technology to be used to
facilitate
interactions within the community
The corresponding definition of service has not yet been
finalized
but the sense of the group is that there would be both
a
business/domain centric notion of service as well as an
interaction
focused definition.
In both cases this seems to fit well with the notion of SOA that
is
evolving in this group and in the SOA
Demo.
Regards,
Cory Casanave
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