What is a SessionFactory and how is it different from Session?

SessionFactory:

• Factory class that creates Session objects
• Thread-safe and immutable
• Expensive to create, typically one per application
• Holds second-level cache data
• Configuration is read-only after creation

Session:

• Interface between Java application and Hibernate
• Not thread-safe
• Lightweight and inexpensive to create
• Represents a single unit of work
• Should be created and closed for each transaction

// SessionFactory - created once
SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();

// Session - created per transaction
Session session = sessionFactory.openSession();
// ... perform operations
session.close();