Kraken JPA

  1. Kraken JPA
    1. Requirements
    2. Install
    3. POM Configuration
    4. iPOJO Handler Configuration
    5. Database Configuration
    6. Declarative Transaction Support
    7. Kraken JPA Script
    8. Kraken JPA Class Diagram
    9. History

Kraken JPA is based on hibernate 3 and provides declarative transaction feature.

Requirements

  • kraken api 1.0.0
  • slf4j api 1.5.6
  • ipojo 1.2.0
  • hibernate 3.3.0.SP1
  • hibernate annotations 3.4.0.GA
  • hibernate entity manager 3.4.0.GA
  • hibernate commons annotations 3.3.0.GA

Install

kraken> bundle.install org.krakenapps kraken-jpa 1.1.0

POM Configuration

<Import-Package>
  javassist.util.proxy,
  org.hibernate.proxy,
  org.hibernate.exception,
  org.hibernate,
  org.hibernate.dialect,
  javax.persistence,*
</Import-Package>
  • You MUST import above packages for JPA model bundle.
    • Otherwise, you will encounter HibernateProxy ClassNotFoundException.

iPOJO Handler Configuration

<component classname="com.example.Component">
	<provides />
	<requires field="entityManagerService" />
	<jpa:Transactional name="entityManagerFactoryName" />
</component>
  • jpa xml namespace is org.krakenapps.jpa.handler. You MUST use this namespace because iPOJO interpret it by special handler convention.
  • entityManagerService's type is ThreadLocalEntityManagerService. iPOJO will inject ThreadLocalEntityManagerService object for you.
    • ThreadLocalEntityManagerService.getEntityManager() will return an EntityManager object in current thread context.
  • entityManagerFactoryName is alias for JPA entity manager factory.

Database Configuration

  • Kraken JPA recognizes two configuration files in bundle.
    • OSGI-INF/kraken-jpa/classes file have JPA entity classe names line by line.
    • OSGI-INF/kraken-jpa/config file contains hibernate configurations. (properties file format)
  • You can load JPA entity bundle at kraken console.
    • "jpa.register [bundle id] [entity manager factory name]" script command will load above configuration files in specified bundle and create entity manager factory with configurations.
  • You can also create entity manager factory programmatically.
    • Find the service reference for org.krakenapps.jpa.JpaService interface.
      • e.g. BundleContext.getServiceReference(JpaService.class.getName());

Declarative Transaction Support

  • @Transactional method annotation provides declarative transaction feature.
    • ThreadLocalEntityManagerService will begin transaction at method entry and commit transaction at method exit. If any error occured, transaction will be rollbacked. Finally, the EntityManager object closed.
  • TransactionOption (from 1.1.0 release)
    • @Transactional has TransactionOption.Required by default.
    • TransactionOption.Required: Shares a transaction, if one exists, and creates a new transaction if necessary.
    • TransactionOption.RequiresNew: Executes the method with a new transaction, regardless of the state of the current context.
    • TransactionOption.Supported: Shares a transaction, if one exists.

Kraken JPA Script

  • jpa.list: list all registered entity manager factories.
  • jpa.register [bundle id] [entity manager factory name]: load configuration from specified bundle and register entity manager factory.
  • jpa.unregister [entity manager factory name]: unregister and close entity manager factory.

Kraken JPA Class Diagram

History

  • 1.1.1 release: Fixed handler validation bug at boot time.
  • 1.1.0 release: Added TransactionOption to @Transactional. Nested @Transactional declaration is supported.
  • 1.0.0 release: Implemented using hibernate.