use case digram and fully developed use case domain modeling system sequence digram

​[login to view URL] Book Exchange is a type of eBusiness exchange that does business entirely on the Internet. The company acts as a clearing exchange for both buyers and sellers of used books. In order for a person to offer books for sale, he must register with Violt.com. The person must provide a current physical address and telephone number as well as a current email address. The system will then maintain 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. Information required includes all of the 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 that buyers can use the search engine to search for books. The search engine allows searches by title, author, category, and keyword as additional information about the book. People desiring to buy books search for the books they want. When they decide to buy, they must open a buyer account with a credit card to pay for the books. The system maintains all of this information on secure servers. When a request to purchase is made, along with the payment, [login to view URL] sends an email notice to the seller of the book that was chosen. It also marks the book as sold. The system maintains this as an open order, until the system receives notice that the books have been shipped. Once the seller receives notice that a listed book has been sold, then he must notify the buyer, via email within 48 hours that the purchase is noted. Shipment of the order must be made with 24 hours after the seller sends the notification email. The seller sends a notification to both the buyer and [login to view URL] when the shipment is made. After receiving notice of shipment, [login to view URL] maintains the order in a shipped status. At the end of each month, a check is mailed to each seller for all of those book orders that have been in a shipped status for thirty days. The thirty-day wait is to allow the buyer to notify [login to view URL] if for some reason the shipment does not arrive, or if the book is not in the same condition as advertised. The buyers can, if they desire, 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 [login to view URL] as a major outlet for selling books. So a service code is an important indicator to potential buyers.