• Interfaces are used to deliver descriptive messages
defined through extensible schemas (i.e. a schema
defines the vocabulary and structure of messages). An
extensible schema allows new versions of services to
be introduced without breaking existing services.
Messages are not intended to describe the system
The above example illustrates that interfaces play an impor
tant roll in any system. For a distributed application system
interfacing is less error-prone and comparably costlier. It is
quite difficult to implement without knowing the system
behavior across different platforms and languages. It is better
to reuse the few generic interfaces for all the applications.
We can send any kind of messages over the interfaces just
Service Oriented Architectur by following the few kinds of
• Since the service provider is responsible to solve any
kind of problem therefore the message must be descriptive
rather than instructive. It’s just like going to a
place an order without bothering the
• Service provider will not be able to understand if the
message is not properly formatted by using the standard
rules. Providing the limitations to a message is the
basic need to make the communication most effective.
It is easier to understand as long as the message is
restricted, although it is much expensive to reduce
Broadly SOA can be classified into two terms: Services
Services: A service is a function or some processing logic or
business processing that is well-defined, self-contained, and
does not depend on the context or state of other services.
Example of Services are Loan Processing Services, which
can be self-contained unit for process the Loan Applications.
Other example may be Weather Services, which can be
used to get the weather information. Any application on the
network can use the service of the Weather Service to get the
Connections: Connections means the link connecting these
self-contained distributed services with each other, it enable
client to Services communications. In case of Web services
SOAP over HTTP is used to communicate the between
The following figure is a simple illustration of the serviceoriented
architecture. It shows how a service consumer sends
a service request to a service provider. After accepting the
request, service provider send a message to the service
consumer. In this case a service provider can also be a service
Different Technologies Used:
SOA is much different from point-to-point architectures.
SOA comprise of loosely coupled, highly interoperable
application services. These services can be developed with
different development technologies (such as Java, .NET,
C++, PERL, PHP), the software components become reusable
i.e. the same C# (C Sharp) service may be used by a
Java application (and/or any other programming language).
||a self-contained, stateless business func
tion which accepts one or more requests
and returns one or more responses through
a well-defined, standard interface. Services
can also perform discrete units of work such
as editing and processing a transaction.
Services should not depend on the state of
other functions or processes. The echnol
ogy used to provide the service, such as a
programming language, does not form part
of this definition.
||Sequencing services and providing addi
tional logic to process data. Does not
include data presentation.
||Not depending on any pre-existing condi
tion. In a SOA, services should not depend
on the condition of any other service. They
receive all information needed to provide a
response from the request. Given the
statelessness of services, service consum
ers can sequence (orchestrate) them into
numerous flows (sometimes referred to as
pipelines) to perform application logic.
||The function which performs a service in
response to a request from a consumer.
||The function which consumes the result of a
service supplied by a provider.
||Service oriented architecture relies on the
ability to identify services and their capabili
ties. Therefore, a SOA depends on a
directory which describes the services
available in its domain.
||The relationship between a service provider
and consumer is dynamic; it is established
at runtime by a binding mechanism.
August 2007 | Java Jazz Up |29
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