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Design ejb design patterns phần 6

Thực hiện một tra cứu JNDI mỗi khi EJBHome là cần thiết có thể tốn kém vì những lý do sau đây: Yêu cầu một cuộc gọi mạng nếu máy chủ JNDI trên một máy khác nhau. Nếu khách hàng không đặt trên cùng một máy như các máy chủ JNDI, sau đó các cuộc gọi đến JDNI sẽ yêu cầu một cuộc gọi mạng. | CHAPTER 6 From Requirements to Pattern-Driven Design So you have this great idea for an application and you have already gone through the process of outlining all the use cases that your application must support. How do you actually map this conceptual understanding of the business problem to a J2EE application design How do the patterns presented in this book fit in Different processes and best practices have been established for going from a business problem to a concrete design. This chapter will not illustrate any one process and will not recommend any methodology. Rather we will take a set of real-world requirements and show how they can be realized as pattern-driven architectures. I recommend that you browse the patterns in Part One before reading this chapter. You may also need to periodically refer back to the patterns while reading this. This chapter is also a walk-through of all the patterns presented in this book. Thus after having read this chapter you should have a very good idea of how all the patterns of this book can be applied to your own real-world projects. The application we will design together is the forums subsystem of The-ServerSide.com J2EE Community the industry s source of J2EE news discussions patterns application server reviews and articles. Note that this book does not have a long-running example TheServerSide will only be used in this chapter to illustrate how pattern-driven designs can be achieved using a real-world application. 123 124 Chapter Six Launched in May 2000 TheServerSide.com was among the first deployed J2EE-based Web sites that included an EJB based back end. Funded and created by The Middleware Company an enterprise Java training and consulting company with Ed Roman author of Mastering EJB 2002 as its CEO the purpose of TheServerSide was to create a community Web site for J2EE developers. On the back end this community was basically just a message-board-style application based on EJB. In fact the very first version of .