In this tutorial, the online bookshop that you created in the last tutorial (Online Bookshop) will be extended to include the following functions and BSPs:

• The page newuser.htm is used to register new customers. New customer data is stored in the customer table BSCUSTOMER. The page cnewuser.htm shows the customer that the registration has been successfully completed. For subsequent orders, the customer simply logs on on the page order.htm using his or her user ID (e-mail address) and password.
• The page basket.htm is the most important addition. This page displays the current status of the shopping basket. The user can delete entries and modify the quantity of an item. If the connection is terminated and then re-opened, the current status of the shopping basket can be regenerated using a cookie.
• Initally, you will use the application class CL_BSP_TUTORIAL to implement the above functionality. This class contains the methods for maintaining the shopping basket.
• Caching is used with the results page results.htm.
• Error messages that are output in the case of incorrect user information are implemented using the messages object. Error pages error.htm and invalid_isbn.htm, which are available in the third tutorial, are not used as a result.
• Some of the error messages have been declared as online text repository texts as an example. OTR texts have the advantage that they are connected to the SAP translation system.

The ways in which the online bookshop can be extended are described in the section Extending the Online Bookshop.