Service Oriented Architecture (SOA)

What is a Service Oriented Architecture (SOA)?

The term service oriented architecture (SOA) was introduced to describe the overall approach of building loosely coupled distributed systems with minimal shared understanding among system components. In short, SOA can be thought of as a collection of loosely coupled components (or services) that pass messages between each other over the network or internet. Examples of SOAs include Microsoft's DCOM and OMG's CORBA.

With the introduction of the technologies SOAP, WSDL and UDDI in 2000, arose the architecture known as Web services. Within a Web service framework applications are built by assembling `services' (basically a component with a web hosted XML proxy), that define reusable business functions. By using the open XML interfaces between components, developers can construct applications incrementally from available services. Moreover, since a Web service wrapper can be placed around virtually all systems, within the present climate of multi-faceted Enterprise software systems Web services provide a compelling interface choice for SOA implementations.

Keys Features of SOA and Web services

Service based development is the latest incarnation of component based development which itself is motivated by the desire to achieve higher levels of software reuse. Though Web services are the most compelling implementation of a SOA approach the functionality they offer to developers has been available in the past through other SOA implementations such as CORBA. However, Web services do have the following advantages over earlier implementations of SOAs:

1. No Lock in - Since Web services are based on open standards (i.e. WSDL, XML, HTTP) a Web service based application allows open access and interoperability of your systems data and applications.
2. Simplified Developer Experience - Web services are designed to simplify the process of developing distributed Web enabled applications, which not only reduces the cost of developing distributed applications but also allows a wider potential user and developer base.
3. Universal Platform and Tool Support - For the first time all the major vendors including IBM, Microsoft, BEA, Sun, HP, Borland,... have agreed on a standard for distributed computing in which their platforms and tools will be able to interoperate.