2. Java Persistence Problem
• Closest native language support
– Serialization
• Lifecycle
– Begins and Ends with JVM
• Identity
– Equals / Hashcode / Memory Location
• Data Types
– Int/long/string..
• RDBMS
– Long term persistence / Primary Key
– SQL
– VARCHAR / NUMBER
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3. Java Persistence Technologies
• Object Relational Mappers – ORM’s
– Map Java objects to Relational database
table records e.g.
– Top Link / Hibernate
• Java Data Objects (JDO)
– Apache jdo
• JDBC
• Java Persistence API (JPA)
– Hibernate
– Top Link
– Open JPA
• EJB
• Custom
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6. Hibernate - Relational Persistence for Java
• XML file to map POJO to Tables
• Configuration
• Classes to bootstrap the framework
• JPA Implementation
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8. Hibernate ORM
• Generators
– native
– increment
– sequence
– assigned
– hilo / identify / uuid.hex / uuid.string / foreign
• Version
– Prevents invalid overwrites
• Property
– String – specify length
– BigDecimal – specify precision/scale
– Date / Timestamp / Long - nothing to specify
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9. Hibernate ORM
• References
– http://www.mkyong.com/tutorials/hibernate-
tutorials/
– http://docs.jboss.org/hibernate/orm/3.3/refe
rence/en/html/index.htmlPrevents invalid
overwrites
– Sample code - http://codeserver/demo-
repository/svndemo/anisht/trunk/training/hib
ernate
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10. Hibernate ORM
• To-Do
– One-to-Many using foreign keys
– Many-to-One
– Many-to-One using foreign keys
– One-to-One
– Run the same examples against SQL Server
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1. Behind the products 2. IT management peace of mind Freedom of choice Any relational database - oracle/mysql/mssql/db2 Any application server - JBoss, Websphere, Weblogic - even Tomcat! Any os - Windows, Linux, *nix Any hardware - well, almost :-) - no mainframes Good corporate citizen Integrates with monitoring systems - Integrates with various SSO systems - Siteminder, CAS, AD, Custom Solutions Easy test instance creation Built in purge/backup solution Test automation Minimal IT involvement 3. High performance/High Scalability 4. Industrial strength Cluster enabled - Application and database failover 5. Open Source No Vendor Lock-in Community Contribution 6. Device inclusive Tablets / Smart Phones / Desktop
Closest to persistence in Java means Serialization Objects created and destroyed based on scope, GC frequency – eventually JVM Objects identified by Memory location by default, or by overriding the equals/hashcode methods No Mapping to Relational databases – Primary Key / Foreign Key / Data type constraints
Several competition mechanisms to solve the problem of Java Object Persistence ORM -> Object to Relational Database JDO -> Object to File/XML/Relational database – Multiple targets, JDOQL, Annotations, XML Custom like iBatis -> Using SQL/Stored Procedures JPA -> Object to Relational Database, JQL, Annotations JDBC -> Using SQL’s EJB’s -> Entity Beans
Configure which database you want to connect to / the dialect, driver etc.
