PowerPoint Presentation

Hibernate ORM
& JPA Overview

Brett MeyerSenior Software EngineerHibernate ORM, Red Hat

Brett Meyer

JBoss Overlord (SOA Governance)

Hibernate ORMORM 4 & 5 development

Hibernate OSGi

Developer community engagement

Red Hat support, Hibernate engineering lead

Other contributionsApache Camel

Infinispan

Contact me@brettemeyer or +brettmeyer

Freenode IRC: brmeyer

github.com/brmeyer
/HibernateDemos

slideshare.net/brmeyer

ORM? JPA?

ORM: Object/Relational Mapping

JPA: Java Persistence API

Hibernate ORM provides its own native API, in addition to full JPA support

Annotations and XML

Overview

JDBC

Why ORM?

Why JPA?

Hibernate ORM

Demos

JDBC

JDBC

Java Database Connectivity

Java SE library for querying/updating database data

Mainly focused on relational DBs

Manages Connections to the DB, either directly or through a 3rd party Connection Pool

Database vendors provide their own JDBC driver libraries

JDBC (cont'd)

API abstracts common interactions, data types, etc.

Execute SQL through Statements

Query returns received through ResultSets

Transactional

Cacheable

JDBC Demo

Why ORM?

ORM

Object/Relational Mapping

Persistence: Data objects outlive the JVM app

Maps Java POJOs to relational databases (one type of persistence)

Why ORM?

Domain Model patternFocus on business concepts, not relational DB structure

Interconnected objects

Each object is a meaningful individual/concept

OO concepts: inheritance, object identity, etc.

Navigate data by walking the object graph, not the explicit relational model

Why ORM? (cont'd)

Increased development speed & reduced codeNo by-hand mapping of JDBC ResultSets to POJOs

Less work synchronizing code with relational DB changes

Less JBDC boilerplate (repetitious CRUD)

Focus on business logic

Why ORM? (cont'd)

PortabilityMostly DB independent (exception: some types of features, identifier generation, etc.)

Query abstractions (OO APIs, OO-structured languages, etc.)

Vendor-specific SQL is auto generated

Why ORM? (cont'd)

PerformanceGranular control of when, how, how much data/relationships to load, based on the business logic

Object and query caching

Concurrency & multiple-tenancy

Transactional

Scalable

Extendable (many types of extension points)

ORM FUD

ORMs are slow and generally awful.http://www.slideshare.net/brmeyer/hibernate-orm-performance-31550150

ORMs are over complicated.Back in the EJB/XML days, maybe.

Annotations FTW!

ORM Demo

Why JPA?

JPA

Java Persistence API

JSR 317 (2.0) & JSR 338 (2.1)

Included in both Java SE & Java EE

Provides portability between JPA implementations (with caveats)

Same ORM concepts, but standardized API and query language (JPQL)

JPA Demo

Hibernate ORM

Hibernate ORM

JPA implementation and 100% TCK compliant

Native featuresHQL (Hibernate Query Language): similar to JPQL, but extended

Criteria API

Performance: Fetch strategies, caching, bytecode enhancement, etc.

Extension points

Rich tool set (schema generation/validation, etc.)

Part of JBoss Community

Hibernate Family

Not just ORM

Hibernate Spatial

Hibernate Envers

Hibernate OSGi

Hibernate Search

Hibernate OGM

Hibernate Validator

Hibernate Shards

http://www.slideshare.net/brmeyer/hibernate-orm-features

We've barely scratched the surface!

How to Help:

hibernate.org
/orm/contribute

QUESTIONS?

Q&A

Freenode IRC: brmeyer

@brettemeyer

+brettmeyer