A possible sequence of events

client                             db server                                           info server  


[:get :list]. ------------------------------------------------------------------->
                 <-------------------------------------------------------------------                                                                                                     
[:list :items] ------------->
                    <------------

:item10 :price ?y. ---------->
                              <---------- :item10 :price :10.

[:order :item10; :quantity :50]
                      ----------------------------->
                     <------------------------------   [:order_accepted "100345";
                                                                 :account "123-34562-45"].