Problem
Let's assume you are planning an e-commerce startup company called Rent-a-Boi. In this system, the User needs to input his/her user id and password. If the credentials are wrong, the system will show an error message to the user. A user can search for a book. If the book is unavailable, users can request that too. Users can also buy books from this system. Users can make payments to the system and the system will send an acknowledgement to the user. The system can send the requested book list to the Admin. Admin can add new books and update the book database.
Now Design the context diagram of the Rent-a-Boi system.
A user inputs his/her credentials to the login process. Login process verifies the information by checking with the user datastore. When a user searches for a book, check the availability process takes that input and checks the availability by looking at the Book datastore. A user can buy books from the system that is handled by the AB2C (add book to cart) process. The checkout process takes all books from the AB2C process, updates the Book datastore and forward the total price to make payment process. On the other hand, the user provides the payment information to the payment process too and it sends an acknowledgment to the user. When a user requests a new book, the request book process forwards the requested book information to the Admin. Admin can add new books to the Book datastore or update the datastore with the new collection.
Now Design the Level-1 diagram of the Rent-a-Boi system.