This case-study describes the requirements of an airline travel agency who want to develop a website to allow customers to make online bookings. The outline requirements are described as follows:-

All customers will be able to access the website to view the different destinations available and the respective flight details. They will also be allowed to check if there are seats available for any flight they wish before making their bookings. Another facility to be provided to all customers is that they will post reviews on the website and also browse the reviews of other customers.

A customer must first register online with the airline company to be able to make a booking. He/she will fill in the registration form and will then be redirected to the login page where the user id and password must be entered to login the secured website. If a member forgets his user id and/or password, he may contact the webmaster by e-mail. The latter will then forward the details to that client within 2 working days. A member can modify his personal details but cannot cancel his membership. It is only the webmaster that can remove him from the database, thus he will have to send an e-mail to webmaster informing him of same. A member can also modify his booking as much as he wants provided the flight is not scheduled after the next 10 days. If there are only 10 days remaining before the flight then the customer can either confirm his booking online or cancel the booking.

The webmaster will also be responsible for some administrative duties. One of his tasks will be to track and monitor all flights taken by the customers. Thus if the customer is a regular one, he will be offered discounts on his next flights at the discretion of the company. Monthly reports will be prepared by the webmaster showing the customer and flight details and these will be used by management.

The webmaster will also have the responsibility to modify flight details, cancel flights from the website and post messages in a section to inform the customers about any changes. He will view the reviews posted and then decide about any modifications that can be made to improve the user-friendliness and overall proper functioning of the website.

These are some of the basic requirements identified for the online system of the airline travel agency.

Question

(a) Draw an appropriate use-case model describing the processes that take place in this system and the actors that stimulate and take part in it. Give the Use-Case specification for one of the identified use-cases.

(b) Draw a class diagram showing the classes involved in the system, their attributes, methods, relationships and relationship multiplicity. Show at least one example of each one of the following concepts: inheritance, aggregation/composition.

(c) Draw a Sequence Diagram for one of the identified use cases. Only one is sufficient for this part.

(d) Draw a state transition diagram for one class identified in the class diagram from part (b) above.