User           
                    Shipment    Service           Initialize
                    Info        Request           Module   
                                                              
                      |  A         |                 |         
                  . . |. |. .  . . |. . . . . . . . .|. . . . . . . . .
                  .   |  |         |                 |     ShipAPI.pm . 
                  .   V  |         |                 V                . 
                  .                |                                  . 
                  . initialize     |            _  shipper            . 
                  . object         |           |   config info        . 
                  .          ______|           |                      . 
                  .         |           . . . .|. . . . . . . . . . . . 
                  .         |           .      |                 
                  .         V           .     .V. . . . . . . . . . . . 
                  .                     .     .   ShipAPI::carrier.pm .
                  .      parse          .     .                       .
                  .      request   <------------>   Available         .
                  .                     .     .     Services          .
                  .         |           .     .                       .
                  .         |           .     .                       .
                  .         V           .     .                       .
                  .                     .     .                       . 
                  .      translate      .     .     field             . 
                  .      & validate  <---------->   translation       . 
                  .      fields         .     .     tables            . 
                  .                     .     .                       . 
                  .         |           .     .                       . 
                  .         |           .     .                       . 
                  .         V           .     .                       . 
                  .                     .     .                       . 
                  .      fill XML       .     .                       . 
                  .      template    <---------->   XML template      . 
                  .                     .     .                       . 
                  .         |           .     .                       . 
                  .         |           .     .                       . 
                  .         V           .     .                       . 
                  .                     .     .                       . 
    to carrier    .      transmit       .     .     URI, Auth         . 
    server      <------  HTTPS       <---------->   & access          . 
                  .      request        .     .     info              . 
                  .                     .     .                       . 
                  .                     .     .                       . 
    from          .      receive        .     .                       . 
    carrier     -------> HTTPS          .     .                       . 
    server        .      response       .     .                       . 
                  .                     .     .                       . 
                  .         |           .     .                       .
                  .         |           .     .                       . 
                  .         V           .     .                       . 
                  .                     .     .                       . 
                  .      parse XML      .     .                       . 
                  .                     .     .                       . 
                  .         |           .     .                       . 
                  .         |           .     .                       . 
                  .         V           .     .                       . 
                  .                     .     .                       . 
                  .       translate     .     .     response          . 
                  .       response    <--------->   translation       . 
                  .       data          .     .     tables            . 
                  .                     .     .                       . 
                  .         |           .     .                       . 
                  . .  .  . | . . . . . .     . . . . . . . . . . . . . 
                            |                                        
                            V                                        
                                                                     
                         Asynchronous                                
                         User Response                               
                        (via callback?)