The principle behind service-oriented architecture (SOA) is to allow using applications as a service by other applications regardless of the platform (type of vendor, product, or technology) being used on either side (service and service consumer). This allows communication and data exchange between applications built on heterogeneous platforms without the need of any additional programming or making changes to the services. What we look for here is seamless integration between any type of applications.

Following image can help you understand more about SOA: