sequence diagram

9:buy a travel package

:Hotel

3:return airline list and information

5:return hotel room list and information

7:return hotel room list and information

8:return the list and information

12:return transaction finished

2:inquire about airline list and information

:Customer

:Airline Company

11:provide information

1:inquire about the list and information

:Car Rental Company

:Travel Agency System

10:create an order

6:inquire about cars list and information

4:inquire about hotel room list and information