Advantages of SOA:
Loosely-coupled connection: Loose-coupling is the key attribute of SOA.
Each service component is independent from other services due to the stateless service feature.
The implementation of a service will not affect the application of the service as long as the exposed interface is not changed.
It makes SOA software much easier to evolve and update.
Interoperability: Technically any client or any service can access other services regardless of their platform, technology, vendors, or language implementations.
Reusability: Any service can be reused by any other service,. Because clients of a service only need to know its public interfaces, service composition and integration become much easier.
SOA based business application development comes much more efficient in term of time and cost.
Scalability: Loosely coupled services make themselves easy to scale.
The coarse-grained, document-oriented, and asynchronous service features enhance the scalability attribute.