Notes – Hibernate Architecture

Hibernate architecture is designed to manage all database-related operations in a structured and efficient way.

It works as a bridge between Java objects and relational database tables.

---

Core Layers of Hibernate Architecture

Hibernate has four key layers:

Layer	Description
Java Application	Your main Java code that uses Hibernate for DB operations.
Hibernate Framework	Core Hibernate APIs like Session, Transaction, Query, etc.
JDBC/Database Layer	Low-level JDBC API and actual database system.
Configuration Layer	Contains mapping and setup details (hibernate.cfg.xml, annotations).

---

Hibernate Architecture Components

Component	Role in Architecture
Configuration	Reads configuration files and sets up Hibernate.
SessionFactory	Creates sessions. Heavy object—should be created only once.
Session	Lightweight, short-lived object to interact with DB.
Transaction	Manages a unit of work like commit or rollback.
Query / HQL	Executes queries on Java objects using HQL or native SQL.
Persistence	Refers to storing and retrieving Java objects in/from the database.

---

Hibernate Workflow (Simple Flow)

1. Application loads configuration.
2. SessionFactory is created once at startup.
3. Session is opened when DB interaction is needed.
4. Transaction is started to ensure atomic operation.
5. SQL or HQL queries are executed via Session.
6. Transaction is committed or rolled back.
7. Session is closed.

---

Diagram (Text Representation)

Java Application
     ↓
Configuration → SessionFactory
                       ↓
                   Session
                       ↓
                 Transaction
                       ↓
                  JDBC / Database