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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