To make things a little easier, and more fun, we will attempt to discuss all the concepts in this book in the context of one imaginary business, a cruise line called Titan. A cruise line makes a particularly interesting example because it incorporates several different businesses: a cruise has cabins that are similar to hotel rooms, serves meals like a restaurant, offers various recreational opportunities, and needs to interact with other travel businesses.
This type of business is a good candidate for a distributed object system because many of the system's users are geographically dispersed. Commercial travel agents, for example, who need to book passage on Titan ships will need to access the reservation system. Supporting many--possibly hundreds--of travel agents requires a robust transactional system to ensure that agents have access and reservations are completed properly.
Throughout this book we will build a fairly simple slice of Titan's EJB system that focuses on the process of making a reservation for a cruise. This will give us an opportunity to develop enterprise beans like Ship, Cabin, TravelAgent, ProcessPayment, and so forth. In the process, you will need to create relational database tables for persisting data used in the example. It is assumed that you are familiar with relational database management systems and that you can create tables according to the SQL statements provided. EJB can be used with any kind of database or legacy application, but relational databases seem to be the most commonly understood database so we have chosen this as the persistence layer.
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