Service-Oriented Architecture - Guide to Cloud Computing for Business and Technology Managers - page 153

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Service-Ori ented Architecture
Integration seems to be one of the most important strategic priorities mainly
because new innovative business solutions demand integration of dif-
ferent business units, business systems, enterprise data, and applications.
Integrated information systems improve the competitive advantage with
unified and efficient access to the information. Integrated applications make
it much easier to access relevant, coordinated information from a variety of
sources. It is clear that replacing existing systems with new solutions will
often not be a viable proposition. Companies soon realize that the replace-
ment is more complicated, more complex, more time consuming, and more
costly than even their worst-case scenarios could have predicted: too much
time and money have been invested in them, and there is too much knowl-
edge incorporated in these systems. Therefore, standard ways to reuse exist-
ing systems and integrate them into the global, enterprise-wide information
system must be defined.
The modern answer to application integration is a SOA with Web Services;
SOA is a style of organizing (services), and Web Services are its realization.
An SOA with Web Services is a combination of architecture and technol-
ogy for consistently delivering robust, reusable services that support today's
business needs and that can be easily adapted to satisfy changing business
requirements. An SOA enables easy integration of IT systems, provides
multichannel access to your systems, and automates business processes.
When an SOA with its corresponding services is in place, developers can
easily reuse existing services in developing new applications and business
processes.
A service differs from an object or a procedure because it is defined by
the messages that it exchanges with other services. A service's loose cou-
pling to the applications that host it gives it the ability to more easily share
data across the department, enterprise, or Internet. An SOA defines the
way in which services are deployed and managed. Companies need IT sys-
tems with the flexibility to implement specialized operations, to change
quickly with the changes in business operations, to respond quickly to
internal as well as external changes in conditions, and consequently gain a
competitive edge. Using an SOA increases reuse, lowers overall costs, and
improves the ability to rapidly change and evolve IT systems, whether old
or ne w.
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