Chapter 3. Domain models and metadata

 

In this chapter

  • Discovering the CaveatEmptor example application
  • Implementing the domain model
  • Object/relational mapping metadata options

The “Hello World” example in the previous chapter introduced you to Hibernate; certainly, it isn’t useful for understanding the requirements of real-world applications with complex data models. For the rest of the book, we use a much more sophisticated example application—CaveatEmptor, an online auction system—to demonstrate Hibernate and Java Persistence. (Caveat emptor means “Let the buyer beware”.)

Major new features in JPA 2
  • A JPA persistence provider now integrates automatically with a Bean Validation provider. When data is stored, the provider automatically validates constraints on persistent classes.
  • The Metamodel API has been added. You can obtain (unfortunately not change) the names, properties, and mapping metadata of the classes in a persistence unit.

3.1. The example CaveatEmptor application

3.1.1. A layered architecture

3.1.2. Analyzing the business domain

3.1.3. The CaveatEmptor domain model

3.2. Implementing the domain model

3.2.1. Addressing leakage of concerns

3.2.2. Transparent and automated persistence

3.2.3. Writing persistence-capable classes

3.2.4. Implementing POJO associations

3.3. Domain model metadata

3.3.1. Annotation-based metadata

3.3.2. Applying Bean Validation rules

3.3.3. Externalizing metadata with XML files

3.3.4. Accessing metadata at runtime

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