Hibernate (Model Framework / ORM Framework)

Hibernate

Hibernate Framework

(Model Framework/ORM Framework)

ORM - Object Relation Mapping)

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Features

1) Makes persistence (INSERT/UPDATE/DELETE) operations transparent (invisible) to developer

In traditional JDBC program developer used to

-obtain connection via --DriverManager.getConnection() method (or) via by connection pooling

--Determine to use Statement or PreparedStatement object

--SQL statement managements

--Consuming resultset

--ensuring Atomicity & Consistency

In Hibernate

--we must write one XML document named "hibernate-cfg.xml" that contains JDBC driver information

--Write one Java Bean class for each table whose properties are same as table columns and their types

--Optionally one XML document that maps each JavaBean to table and its properties, save the document as Student.hbm.xml file

--Input both cfg.xml and hbm.xml files to Hibernate classes. Hibernate classes will internally create conn, stmt etc objects for SQL operations

--If we instantiate JavaBean, assign all the class instance variables with values and invoke only one function on hibernate class called save(bean) as argument. Hibernate reads javabean values, prepares one dynamic SQL statement and inserts record into DB.

--Atomicity and consistency are managed by hibernate implicitly

--This way hibernate reduces the JDBC code to do SQL operations on DB

--That means in Hibernate what developer must do is map one Java class to table. Hibernate maps the java object to one entity / record in the DB

-Hibernate does object-entity relation management

-Not only hibernate does persistence operations, it caches all the objects stored via Hibernate and as and when the record is modified in the DB, hibernate updates the state of javabean also. It implicitly avoids inconsistent problems

1) Transparent persistence operations

2) Object level relationship instead of maintaining relationship @ DB level. This is to facilitate portable relationships across all the DBs

3) Instead of fetching records from the DB using SQL and operating on ResultSet, we can fetch objects directly from Hibernate using HQL

4) Caching

-Memory level caching

-Disk level caching