eclipse jpa
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© 2008 by Gordon Yorke made available under the EPL v1.0 | March 20, 2008 |
Eclipse JPA
Gordon YorkeEclipseLink Architecture Committee Member,EclipseLink Core Technical Lead,JPA 2.0 Expert Group Membergordon.yorke@oracle.com
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
What you will learn
• Eclipse Persistence Services Project (EclipseLink) Components
• Focus on EclipseLink JPA Constructing a Persistence Unit Developing with Dali Deployments
Java SE, Java EE
Usage for RCP EclipseLink Extensions
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
Eclipse Persistence Services
• Eclipse runtime project Nicknamed “EclipseLink” Currently Incubating in Technology Project
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
What is EclipseLink
• Based upon product with 12 years of commercial usage • First comprehensive open source persistence solution
EclipseLink JPA: Object-Relational EclipseLink MOXy: Object-XML EclipseLink SDO: Service Data Objects EclipseLink EIS: Non-Relational using JCA EclipseLink DBWS: Database Web Services
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
EclipseLink…
• Shared infrastructure• Easily share the same domain model with multiple persistence
technologies• Leverage metadata for multiple services• Providing enterprise data access and manipulation services to the
Eclipse Ecosystem
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
JDBC
Eclipse Persistence Services (EclipseLink)
JPA MOXy SDO DBWS EIS
Java SE, Java EE, SCA, Spring, OSGi
Legacy SystemsXML
Packaged Apps
JCA
RelationalDatabases
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
Why EclipseLink JPA
• JPA 1.0 compliant implementation• JPA 2.0 in development• Any JDBC/SQL compliant database
Database specific support for Oracle, Derby, MySQL, SQLServer, PostgreSQL and more.
• Extensible and pluggable• Key infrastructure:
Query Framework, Mapping, …
• many valuable advanced features Caching, locking, dynamic enhancement (weaving) …
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
The JPA Specification
• Simple configuration by exception• Extensive use of annotations• XML configuration available
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
ORM
• Mappings @Embeddables
multiple objects but data in same table @Basic/@Id
Simple types mapping to single columns (ie. int, String) @Lob
Binary based data (ie. Images) @OneToOne, @ManyToOne
References to single target object. @OneToMany, @ManyToMany
Collections and Maps
• Class Inheritance All classes in single table Extended fields in separate tables
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
EntityManager
• Contains the lifecycle APIs for the Entities persist(), remove(), merge()
• Contains management APIs for local transactions getTransaction().begin(), getTransation().rollback();
• Contains management APIs for Persistence Context clear()
• Source for Queries createQuery(), createNativeQuery(), find(), refresh()
• Optimistic database locking lock()
• Central interface point for JPA
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
Persistence Context
• Set of objects tracked for changes by Persistence Provider• Objects enter Persistence Context through EntityManager APIs • Has two life expectancies
transactional – entities are no longer tracked at end of transaction extended – entities are tracked for life of Persistence Context unless
cleared.
• Persistence Context ≈ EntityManager Except transactional PC will be propagated to multiple EMs within
Container Managed environment
• Changes will be written at end of transaction or on ‘flush’ call.
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
Queries
• Dynamic or statically defined (named queries)• Criteria using JP QL (object based query language)• Native SQL support (when required)• Named parameters bound at execution time• Pagination and ability to restrict size of result• Single/multiple-entity results, data projections• Bulk update and delete operation on an entity• Standard hooks for vendor-specific hints
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
How to use it
• Create Entities and Map Simple POJOs annotations or XML Database can be pre-existing Generate table definitions later
• Package into Persistence Unit Lots of options
Easiest into .jar OSGi bundle support in development
• Dali Tooling for mapping and packaging persistence unit
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
The Persistence Unit .jar
• Domain model POJOs with or without annotations Each entity must be designated as such and must have a PK
defined.
• META-INF/persistence.xml Deployment configuration
Optional xml based mapping config (META-INF/orm.xml)Can override annotations or provide full mapping config
Datasource name or JDBC connection propertieseclipselink.jdbc.driver, eclipselink.jdbc.connection-url
Entities to check for annotations
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
Java SE vs Java EE
• Java SE deployment Application managed EntityManagers
Local transactions Persistence Context always ‘extended’
Java SE bootstrapping APIs -javaagent jvm argument for dynamic weaving
• Java EE Container managed EntityManager
PersistenceContext JTA transaction scoped or ‘extended’ @PersisteneContext annotation for injection
Application Managed EntityManager PersistenceContext always extended JTA though ‘joinTransaction’ APIs
Dynamic weaving automatic
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
Inside Eclipse Rich Client
• Referenced library or OSGI OSGi EclipseLink bundles in development
http://wiki.eclipse.org/EclipseLink/Development/OSGi_Proof_of_Concept
• Application managed EntityManagers Local transactions Persistence Context always ‘extended’
• Java SE bootstrapping APIs• Static weaving
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
Demo
• Persistence Enable a Rich Client through bundles Tools,
Dali EclipseLink
Troubleshooting Check that the Persistence Unit Bundle is included in your launch Dali sets Persistence Unit name to project name by default make
sure it matches the name in ComicsModel.java
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
EclipseLink JPA Extensions
• Weaving Lazy loading all non PK fields Performance options - change tracking, batch writing, batch reading
• Mappings @BasicMap, @BasicCollection, @PrivateOwned, @JoinFetch @Converter, @TypeConverter, @ObjectTypeConverter
• @NamedStoredProcedureQuery IN/OUT/INOUT parameters, multiple cursor results
• Extensions supported through annotations and XML • Query hints
refreshing, locking, parameter binding, database platform hints …
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
Extensions - Locking
• Data Locking policies Optimistic: Numeric, Timestamp, All fields, Selected fields,
Changed field Pessimistic
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
Extensions - Entity Caching
• Entity caching L2 shared across transactions/users Coordination in a clustered deployment
• Application specific configuration Caching: per Entity or per Persistence Unit
eclipselink.cache.shared(default|<entity>)
Cache Type and Size: Weak, Soft-Weak, Full, None* eclipselink.cache.type(default|<entity>)
Expiration/Invalidation Time to live, Time of day, API
Coordination (cluster-messaging) Messaging: JMS, RMI, RMI-IIOP, … Mode: SYNC, SYNC+NEW, INVALIDATE, NONE
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
Performance and Tuning
• Highly configurable and tunable Principle: minimize and optimize database calls Enable application specific tuning
• Flexibility allows efficient business models and relational schemas to be used
• Leverages underlying performance tuning features Java, JDBC and the underlying database technology Batch Reading, Batch Writing, Joined Reading, etc…
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
DEMO
• Extensions in action
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
EclipseLink in the Eclipse Ecosystem
• Provide an Eclipse persistence solution easily consumable by any project
Storage of metadata in RDBMS, XML, EIS XML Messaging infrastructure
• Eclipse Projects Dali JPA Tooling Project Teneo to use EclipseLink for EMF model persistence Maya for storage of deployment configuration SOA Project for EclipseLink SDO
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
Where are we going?
• Delivery of 1.0M5-incubation milestone • 1.0 Release Planed for June 2008• Specifications: JPA2.0, JAXB 2.0, SDO 2.1• OSGi packaging and usage examples• Database Web Services (DBWS)• Data Access Service (DAS) - SDO with JPA
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
How can you get involved?
• Users The 1.0M5-incubation milestone is now available Try it out and provide feedback File bug reports and feature requests
• Contributors Contribute to roadmap discussions Bug fixes
• Committers Very interested in growing committer base
Eclipse JPA | © 2008 by Gordon Yorke; made available under the EPL v1.0
More Information
• www.eclipse.org/eclipselink• Newsgroup: eclipse.technology.eclipselink• Wiki: wiki.eclipse.org/EclipseLink• Mailing Lists:
eclipselink-dev@eclipse.org eclipselink-users@eclipse.org
• Blogs Committer Team blog: eclipselink.blogspot.com
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