Characteristics of SOA

•In SOA, Services should be independent of other services. 
Altering a service should not affect calling service. 

•Services should be self-contained. When we talk about a RegisterCusomer service it means, service will do all the necessary work for us, we are not required to care about anything. 

•Services should be able to define themselves.
Services should be able to answer a question what is does? It should be able to tell client what all operations it does, what all data types it uses and what kind of responses it will return. 

•Services should be published into a location (directory) where anyone can search for it. 

•As I said, SOA comprises of collection services which communicate via standard Messages.
Standard messages make them platform independent. 
(Here standard doesn’t mean standard across Microsoft it means across all programming languages and technologies.) 

•Services should be able to communicate with each other asynchronously.

•Services should support reliable messaging.

Means there should be a guarantee that request will be reached to correct destination and correct response will be obtained. 

•Services should support secure communication.