312 Informix Dynamic Server V10 . . . Extended Functionality for Modern Business
11.1 An introduction to SOA
At a very simplistic level, an SOA is a collection of services on a network that
communicate with one another in order to carry out business processes. The
communication can either be either data passing or can trigger several services
that implement some activity. The services are loosely coupled, have platform
independent interfaces, and are fully reusable.
SOA is a business-centric, IT architectural approach that supports integrating
your business as linked, repeatable business tasks or services. SOA helps users
build composite applications, which are applications that draw upon functionality
from multiple sources within and beyond the enterprise to support horizontal
An SOA helps hide the IT complexity that is inherent in even seemingly simple
interactions. One key technical foundation of SOA are
Web services, which we
will introduce later in this chapter.
SOA is the architectural style whose goal is to achieve loose coupling among
interacting software agents. A
service is a unit of work done by a service provider
to achieve desired end results for a
service consumer. Both provider and
consumer are roles played by software agents on behalf of their owners.
11.1.1 An SOA example: an Internet bookstore
To better illustrate the usage of an SOA, let us take a look behind the scenes of a
real-world scenario: the ordering process of an Internet bookstore.
The customer point of view
A book is ordered online, and a few days later it is delivered to your home.
What happens behind the scenes
Behind the scenes of your book order, the follow process happens:
Your identity is authenticated.
At the time you register a new account with the Internet bookstore, it needs to
verify your billing address to make sure that you are a valid customer. To do
this, it is very likely using a Web service that is provided by a third-party
provider such as a telecommunications company, a bank, or the government.
Note: SOA is not really new, but the availability of more and improved Web
services applications is making SOA much more powerful and easier to