Case Study :

The EyesHavelt.com Book Exchange is a type of e$-$business exchange that does business entirely on the Internet. The company acts as a clearinghouse for buyers and sellers of used books.

To offer books for sale, a person must register with the EyesHavelt.com. The person must provide a current physical address and telephone number as well as a current e$-$mail address. The system then maintains an open account for this person. Access to the system as a seller is through a secure$,$ authenticated portal.

A seller can list books on the system through a special Internet form. The form asks for all the pertinent information about the book: its category, its general condition, and the asking price. A seller may list as many books as desired. The system maintains an index of all books in the system so buyers can use the search engine to search for books. The search engine allows searches by title, author, category, and keyword.

People who want to buy books come to the site and search for the books they want. When they decide to buy, they must open an account with a credit card to pay for the books. The system maintains all this information on secure servers.

When a purchase is made, the EyesHavelt.com sends an e$-$mail notice to the seller of the book that was chosen as well as payment information. It also marks the book as sold. The system maintains an open order until it receives notice that the book has been shipped. After the seller receives notice that a listed book has been sold, the seller must notify the buyer via e$-$mail within $48$ hours that the purchase is noted. Shipment of the order must be made within $24$ hours after the seller sends the notification e$-$mail. The seller sends a notification to the buyer and the EyesHavelt.com when the shipment is made.

After receiving the notice of shipment, the EyesHavelt.com maintains the order in a shipped status. At the end of each month, a check is mailed to each seller for the book orders that have remained in a shipped status for $30$ days. The $30-$day waiting period exists to allow the buyer to notify the EyesHavelt.com if the shipment doesn't arrive for some reason or if the book isn't in the same condition as advertised.

If they want, buyers can enter a service code for the seller. The service code is an indication of how well the seller is servicing book purchases. Some sellers are very active and use the EyesHavelt.com as a major outlet for selling books. Thus, a service code is an important indicator to potential buyers.

Using the provided diagrams, develop: $($PLEASE DRAW BOTH DIAGRAMS OUT$)$

a$)$ A sequence diagram for the use case Add a seller $(15$ points$)$

b$)$ A design class diagram that includes classes, methods, and navigation attributes $(15$ points$)$