A client creates a Customer entity by invoking the createCustomer method of the CustomerControllerBean session bean. To remove a customer, the client calls the removeCustomer method, which invokes the EntityManager.remove method on the Customer instance.
The CustomerControllerBean session bean has two methods that return multiple customers: getCustomersOfAccount and getCustomersOfLastName. getCustomersOfAccount calls the getCustomers method of the Account entity. getCustomersOfLastName uses the Customer.FindByLastName named query to search the database for customers with a matching last name, which is a named parameter to the query.