,--------------------.                 
|ClientInterface     |                 
|--------------------|                 
|+ void callService()|                 
`--------------------'                 
                                       
                                       
   |,---------------------------------.
   ||ServiceInterface                 |
   ||---------------------------------|
   ||+ void serve(RequestClass  class)|
   |`---------------------------------'
                                       
    ,------------.                     
    |RequestClass|                     
    |------------|                     
    |...         |                     
    `------------'