 +---------+  
 |  user   |  
 |         |  
 +---------+  
   |          
   v          
 +---------+  
 | client  |  
 |         |  
 +---------+  
   ^  |       
   |  |       
 HTTP |       
   |  |       
   v  v       
 +-----------+
 |Web Server |
 |           |
 +-----------+
   |  |       
queries       
   |  |       
   v  v       
 +-----------+
 |PostgreSQL |
 |           |
 +-----------+
