Moving onto the RESTful API; I implemented some HTTP functions like HttpGet, HttpPost, HttpDelete, and etc. I also added some dependency injection onto the program.cs class for the library service and the logger. I had some trouble maintaining the changes to the library. For example, adding a book would not keep the book in the collection. Deleting a book will have no change on the collection. To resolve this, I changed the dependency injection of the library service from transient to singleton to ensure a single instance of the service is maintained for the entire lifecycle of the application.