Requirements of the Web services architecture
  - Enable interoperability
 
  - Reliable: 
    
      - Well defined
 
      - Set of metrics, e.g. for measuring quality of service
 
    
   
  - Clean integration in the Web
 
  - Security and privacy
 
  - Scalability and extensibility: 
    
      - Modular
 
      - Extensible, open-ended