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Subject: RE: [soa-rm] RE: Service definition at nauseum
Dan, good input. So, to tweak
the definition a little more, it would look like: A service (in the context of
SOA) is a capability or function offered and packaged by a provider and made
accessible to consumers “as-is” where access is provided using a
prescribed interface that abstracts (or hides) the implementation details of
the capability or function, and is exercised consistent with the contracts and
policies as specified by its description. From: Hestand, Dan Chris, I agree
that we need to generalize to a “category” of consumers, if you
will. In one sense, it’s saying “service offered by a provider
‘as-is’ for market use”. This gets at the non-specialized
nature of the service and also uses the concept of market segmentation which is
familiar to businesses. I’m not tied to the specific words but the
“as-is” concept is important. I also
firmly believe that the capability is not the service. Rather, the service is
how that capability is realized. In one case, the capability of withdrawing
money from the bank is realized through teller services and in another,
realized through ATM services. The distinction also gets at the
governance/management relationship. Governance and management in SOA Ecosystems
is not applied to capabilities but to the realization of those capabilities:
how they are realized, how they are used, how they are offered. Sort of like
the Government doesn’t legislate what your business can do but it does
legislate how you can do it, offer it, and how consumers can access it. My
opinions… Dan
Hestand Lead
Software Systems Engineer The
MITRE Corp 781.271.3755 phestand@mitre.org From: Bashioum, Christopher D
[mailto:cbashioum@mitre.org] Jeff, I
think I’m ok with this, but there is some tweaking we need to do
still. I’m thinking about the “offered by a provider for a
consumer” part. There is a subtlety here that is important to get
at, and that I believe you were attempting to get at when you mentioned
“accessed via a technology nuetral interface” in a previous
email. I
think the basic idea is something along the lines of “offered by a
provider for a class of consumers”, or “offered by a provider for a
‘generic consumer’” or something along those lines.
What we are getting at is that the service is sort of generic in nature, it is
not optimized for a particular customer. The
way we “used to” do things was to focus on the capability and
do specific integrations as necessary if anyone “else” wanted to
make use of that capability. With SOA, the emphasis is on the
“offered to others”, and all that that entails (especially when the
“others” are part of another ownership domain). That’s
really what we were trying to get at when using the term “mechanism to
access a capability”. I’ve
been thinking about this a *lot* because I realize that the definition
that we currently have in the RM has been distasteful for many, and I think has
been the cause for less adoption of the RM than we would have hoped. The
concept is correct, but the language has been a stumbling block. So ...
if we can capture the idea of “offering for the generic others” I
think we will be in good shape. Note
also that the term capability is really a potential for something, not the
actual doing of something. The noun “service” is the
“performance of duties or work for another”. Another
definition has the “performance of a function for another”.
The term function may be more applicable than capability, where capability
speaks of the potential to do work (capability: qualities,
abilities, features, etc., that can be used or developed; potential) and
function speaks more of a repeatable “chunk” of work. How’s
this for a tweak? A service (in the context of
SOA) is a capability or function offered and packaged by a provider and made
accessible to consumers where access is provided using a prescribed interface
that abstracts (or hides) the implementation details of the capability or
function, and is exercised consistent with the contracts and policies as
specified by its description. From: Estefan, Jeff A (3100)
[mailto:jeffrey.a.estefan@jpl.nasa.gov] Colleagues, Now that some of the message
traffic has settled, here’s another update to the proposed SOA service
definition that should be closer to the mark while allowing for a little wiggle
room. A service (in the context of
SOA) is a capability offered by a provider for a consumer where access is
provided using a prescribed interface that abstracts (or hides) the
implementation details of the capability, and is exercised consistent with the
contracts and policies as specified by its description. Will follow up the threads after
the weekend. Regards... - Jeff |
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