Hibernate Overview

Introduction to ORM

• Object-oriented programming technologies are typically used to implement business logic.
• Object-oriented technology supports the building of applications out of networks of objects with both data and behavior.
• Relational databases are used for persistent data storage
• Relational technology supports the storage of data in tables and manipulation of that data using data manipulation language (DML)
• Impedance mismatch between the two paradigms: objects vs. relations
• ORM toolkits are designed to address this impedance mismatch

Important aspects of ORM toolkits

Mapping specification

Class inheritance

Query language

Persistence

Fetch strategies

Caching

ORM Solutions

Hibernate – Open Source

iBatis SQL Maps – Open Source

TopLink – Commercial

JPA – Java EE 5 Solution

Nhibernate (.NET environment (C#))

Overview of Hibernate

 

Started in 2001 by Gavin King as an alternative to using EJB2-style entity beans

Open Source light-weight ORM solution

Doesn’t require container (light-weight)

Object based model

It is around from quite some time

Very well matured and adopted by a large

developer community

Maintained by a team at JBoss (Redhat) led by Steve Ebersole

Latest Version 4.x

Why Hibernate?

Hibernate was introduced to address the issues of Entity Beans

Hibernate is built on top of JNDI, JDBC, JTA

It uses XML based configuration files for mapping

Supports many databases like Sybase, Oracle, MySQL,other Object Oriented Databases etc.

Easy migration from one vendor database to another

Hibernate generates the JDBC Code based on the underlying vendor database

Hibernate APIs are very simple to learn and use

Provides quite powerful object query language known as Hibernate Query Language (HQL)  

Hibernate Architecture