Many are comparing notes on two well-publicized paths to achieving SOA. The
bottom-up approach is currently the most common variety, where Web services
are created on an "as need" basis to fulfill mostly integration-related
requirements. These services are typically application specific and simply
re-create traditional integration channels over the open Web services
The top-down approach, on the other hand, is one of analysis, deep thought,
and patience. Service-orientation is infused into the business process layer
so that services can be modeled in alignment with business models. The models
themselves may need to be built or further refined in order to fully
incorporate service-orientation principles.
Then, of course, there's the middle ground - an approach that tries to
balance the requirements of the top-down strategy with the efficiency... (more)
With the unwavering prominence of service-oriented architecture (SOA) there
is an increasing interest in understanding what exactly it means for
something to be considered "service-oriented." Thomas Erl recently completed
a lengthy research project for SOA Systems Inc. into the origins of SOA and
the current state of service-orientation among all primary SOA technology
platforms. This body of work contributed to the mainstream SOA methodology
developed by SOA Systems and was also documented in Thomas's new book,
Service-Oriented Architecture: Concepts, Technology, and Design. We ... (more)
Originally inspired by techniques used to design buildings and cities, and
popularized by the Gang of Four during the mainstream emergence of
object-orientation, design patterns have seen us through the various shifts
in architecture, technology, and, of course, design. Pattern catalogs have
periodically emerged, one building on the other, and each revealing a set of
problem-solving techniques and providing invaluable insights as to how and
when those techniques should be used to help us attain our design goals.
SOA has its own history, having risen out of a haze of ambiguity to e... (more)
Should a service only be considered a service if it's reusable? The answer to
this question, as asserted by this pattern, is a firm "no." While agnostic
services (services providing multi-purpose logic with reuse potential, as per
the Agnostic Context pattern), receive the most attention during service
modeling and design phases, it can often be short-sighted to focus only on
agnostic service logic.
Non-agnostic logic represents any type of functionality that is unique to a
given business process or task. In other words, non-agnostic logic is
single-purpose in nature and therefo... (more)
Enterprise-wide harmonization is a desirable and ideal target state that
fully supports pretty much everything SOA and service-orientation stand for.
For those that have achieved such a state, bless your standardized hearts.
You have accomplished something that has eluded many others. However, not
attaining this state does not mean you cannot successfully adopt SOA.
In some circles it has become common to view an SOA initiative as an
all-or-nothing proposition that demands an uncompromising commitment to an
enterprise-wide transformation effort. For those that subscribe to this vi... (more)