soa的三种外观‏

企业经营：
A set of Services that Business wants to expose to Customers and Clients
IT架构: 
An Architectural Style which requires a Service Provider,Requestor and Service Description.
A set of Architectural Principles and Patterns which address characteristics such as Modularity,Encapsulation,Loose Coupling,Separation of Concerns,Reuse,Composable and Single Implementation
IT实现:
A Programming Model compete with Standards,tools,Methods,and Technologies such as Web Services.