Overview of Service-Oriented Architecture (SOA)

In simple words, SOA is collection of various loosely coupled services which communication with each other over a standard interface.

Fundamental Structure

There are two components which make SOA functional. These are Services and Connections.

A service is a well-defined, self-contained stateless function (or processing logic). It is independent of state or context of other services. For example, credit application service, loan /mortgage processing service, payroll processing services, word processing service, credit transactions processing service, etc.
A connection is a link/ standard interface connecting various distributed services with each other, thereby enabling client-services communications. For example, in Web services SOAP is used over HTTP for linking any two services.

How it works

In SOA, service consumer sends one (or more service) REQUESTS to a service provider. The service provider accepting the request and sends one (or more) RESPONSE(s) to the service consumer. The relationship service provider and consumer is dynamic or run-time. alt
SOA involves several services. These services are enlisted in a directory for a given domain. The process of finding the a given service is called discovery. These services are sequenced (orchestration) and put into flows (pipeline) to provide logic.

Technologies involved in SOA

Earlier SOA was based on the DCOM or Object Request Brokers (ORBs).
Nowadays SOA is based on the Web Services and is much different from P2P (Point-to-Point) architectures. SOA services can be developed in different technologies such as ASP, JSP, Python, .NET, C++, PERL, PHP, to mention a few.

The software components are reusable, for example; any other programming language can use a service programmed in ASP. The WSDL standard enables encapsulation, (hiding the vendor / language specific implementation) from the calling service.

Why we need SOA?

SOA implementation brings several benefits. Some of these are enlisted below-

s architecture enables seamless Enterprise Information Integration. Here are some of the Benefits of the Service Oriented Architecture:

· No vendor lock-in
· SOA acts like a giant, enabling seamless integration of enterprise resources.
· Because it is platform independent, company can deploy various software and hardware of their choice.
· SOA training cost is low and existing manpower can be used to run the applications.
· SOA enables not just reuse of existing software (investments), but also inclusion of new applications.