Chapter 1. Entity and Session

In this chapter, we will take an in-depth look at sessions and entities and their lifecycles. It is important to understand the concepts of session and entity when we talk about design concepts, such as session-per-request, session-per-conversation, stateless sessions, and contextual sessions, and discuss the various states of an entity. After all, the only way to master anything is by paying attention to the details. We also explore entities beyond their JPA characteristics and look at Hibernate entities to see the benefits of one over the other. Furthermore, we discuss proxy objects and how they are used.

In this chapter, we will cover the following topics:

• Why this book?
• Quick Hibernate
• Hibernate session:
  • Session internals
  • Contextual sessions
  • Sessions per request, per conversation, and per operation
  • Stateless sessions
• Hibernate entities:
  • Entity lifecycle
  • Types of entities
  • Identity crisis
  • Beyond JPA
• Proxy objects
• Batch processing:
  • Manual batch management
  • Setting the size of the batch
• Using a stateless session