Service Oriented Architecture
Service Oriented Architecture or SOA for short is a
new architecture for the development of loosely coupled
distributed applications. In fact service-oriented architecture
is collection of many services in the network. These
services communicate with each other and the communications
involves data exchange & even service coordination.
Earlier SOA was based on the DCOM or Object
Request Brokers (ORBs). Nowadays SOA is based on
the Web Services. Service Oriented Architecture is
basically an evolution of distributed computing. SOA
provides a modularity of business logic, which can be
presented as service for clients (client as in client-server
architecture). These services are loosely coupled in
nature, in the sense the ‘User Interface’ can remain
completely independent of the service layer.
Loose Coupling : It is more efficient to reuse the functionality
of the existing system rather than building a complete new
system. It is not the task the of Tom Dick and Harry to reuse
the things easily because they (building blocks) are heavily
dependent on each other. There are two types of dependency.
The first one is the real dependency and the second one is
the artificial dependency. A real dependency is one in which
one system depends on the functionality of the other system.
The artificial dependency is the set of factors due to which a
system accepts the features or services provided by the other
system. But the problem is that we create the real dependency
along with the artificial dependency. This is known as
Let’s take an example that includes loose coupling. Suppose
you are going overseas for business and you are carrying your
power adapter. This is real dependency that your need power.
But your adapter’s plug is not getting fit into the outlet, this is
artificial dependency. While looking at the power adapter you
will notice that some of them are varying in shapes and sizes,
while the others are big and bulky in size being used in
The conclusion here is that we can not almost remove the
artificial dependency from the real dependency but can be
reduce up to its minimum. If we are able to reduce the
artificial dependency among the systems, it means we have
achieved the loose coupling. Artificial dependencies can be
reduced to its minimum but the real dependency can not be
Service Oriented Architecture is nothing but the architectural
style to achieve loose coupling among various interactive
systems. In the present time most of the organizations are
implementing IT systems across their various departments. It
is not a big deal, but the challenge is to find the solution that
must be flexible, extensible and best fit for the existing legacy
system. Its not a good idea to replace a legacy system with
the new architecture and it is not only costly but also risky.
For such type of problems Service Oriented Architecture
(SOA) provides the best solution that is more cost effective
and relatively cheap. Although it is not a new concept but SOAneeds more attention with the advent of platform-neutral data
models and platform-independent programs.
Characteristics of Service Oriented Architecture:
• SOA services communicates with messages by using
the XML Schema. Communications among various
consumers, providers and services takes place in
heterogeneous environment with little or no knowledge
regarding to the provider.
• SOA services act as a directory listing and are maintained
by a registry within the enterprise. Applications
invoke the service by looking up the service in the
• Every SOA service contains the quality of service (QoS)
like security requirements such as reliable messaging,
authentication, authorization and policies associated
• WSDL is a standard, used for describing the services
as SOA services that includes the platform independent
XML document containing self-describing interfaces.
SOA is most widely used in the market as it links
computational resources and promotes their reuse. SOA
is helpful as it responds more quickly and makes costeffective
changes according to the market situations. It
also simplifies the usage of the existing IT (legacy) assets
and interconnection among the assets.
SOA isolates the user from the service implementation in order
to run the services on various distributed platform and make it
accessible across the network.
SOA architecture enables seamless Enterprise Information
Integration. Here are some of the Benefits of the Service
• Due to its platform independence, it allows companies
to use the software and hardware of their choice.
• There is no threat of vendor lock-in.
• SOA enables incremental development, deployment,
• Companies can use the existing software (investments)
and use SOA to build applications without replacing the
• The training costs are low, so the available labor pool
can be used for running the applications.
Techniques used by SOA to achieve loose
coupling among interactive software agents:
• Distribute a small set of simple interfaces among all the
participating software agents. The interface contains
only generic semantics and should be available globally
to all providers and consumers.
August 2007 | Java Jazz Up |28
|Pages: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,
|31, 32, 33, 34, 35, 36, 37, 38, 39, 40 Download PDF