Eclipse Web Tools Platform: Developing Java Web Applications by Naci Dai, Lawrence Mandel, Arthur Ryman
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Chapter 8 - The Business Logic Tier

-Thomas Babington Macaulay

The business of everybody is the business of nobody.

The term business logic tier is suggestive enough-this is the layer where the business objects and rules are modeled. It is common practice to build applications with three layers, with each layer hosted on one tier of a three-tier architecture. The business layer lies between the persistence layer, which stores the data, and the presentation layer, which provides the user interface. In this chapter, we'll discuss some of the best practices for developing a business tier and show how WTP can be used to do this.

Although we offer advice here, you should be aware that there is much debate over how to build the business tier. Component architectures, the use of plain (Naked) objects, and service-orientation are some of the most popular approaches (see [Sessions1997], [Pawson2002]).

Component architectures are a natural evolution of OO concepts. They offer coarse-grained business-level functions that are easier to understand, have clear interfaces, and can be distributed over a network. However, component architectures are not without problems. The large variety of component protocols, component interoperability problems, multiple interface languages, and heavyweight runtime infrastructures, and the complexity of standards and technologies have long been causes for concern. Service-Oriented Architecture (SOA) addresses some of the interoperability and integration problems by offering common standards and protocols, such as XML and HTTP (see Chapter 10). Consult the large number of excellent resources available elsewhere for patterns related to business models, uses of component architectures, SOA, and EJBs. We will skip the history here and briefly outline what we believe works.

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Other Sections in This Chapter

  • A Common Business Tier Design
  • Iteration 1: The Domain Model
    • J2EE Utility Projects
    • The Object Model
    • The Service Layer
    • The Data Access Layer
    • Testing
    • Summary of Iteration 1
  • Iteration 2: Developing Session EJBs
    • Adding JBoss
    • XDoclet
    • EJB Projects
    • Creating Session Beans
    • Building a Web Client
    • Running the Application
    • Developing EJB 3.0 with WTP
    • Summary of Iteration 2
  • Iteration 3: Message-Driven Beans
    • A Brief Introduction to MDBs
    • Create an MDB
    • Add a Queue to JBoss
    • Create a JMS Web Client
    • Summary of Iteration 3
  • Summary