net1                                                                                                                   
                                                                                                                            
                                                                                                                            
                                                                                                                            
                                                                                                                            
                                                                                             DB_Main                        
                                                                                                                            
                                                                                             Backend DB                     
                                                                                                                            
                                                                                             CU DB                          
                                                                                             XXX DB                         
                                                                                             YYY DB                         
                                                                                                                            
                                                                                                                            
                                                                                                                            
                                                                                                                            
     net2                                                                                                                   
                                                                                                                            
                                                                                                                            
                                                                                                                            
                                                                                                                            
                                                                                                                     thing_2