Developing applications that use the Java Persistence API

Subtopics

• Develop JPA 2.x applications for a Java EE environment
  Containers in the application server can provide many of the necessary functions for the Java Persistence API (JPA) in a Java Enterprise Edition (Java EE) environment. The application server also provides JPA command tools to assist you with developing applications in a Java EE environment.

• Develop JPA 2.x applications for a Java SE environment
  Prepare persistence applications to test outside of the application server container in a Java SE environment.

• Bean validation in JPA
  Data validation is a common task that occurs in all layers of an application, including persistence. The Java Persistence API (JPA) 2.0 provides support for the Bean Validation API so that data validation can be done at run time. This topic includes a usage scenario where bean validation is used in the JPA environment of a sample digital image gallery application.

• wsjpa properties
  The extension properties of Java Persistence API (JPA) for WAS can be specified with the openjpa or wsjpa prefix. This topic features the wsjpa properties.

• Criteria API
  The Criteria API is an API for building queries with Java objects, as an alternative to building strings for Java Persistence Query Language (JPQL) queries.

• wsappid command
  The Java Persistence API (JPA) specification supports an entity primary key to be made up of more than one column. In this case, the primary key is called a composite or compound primary key. Provide an ID class, specified by the @IdClass annotation, to manage a composite primary key. Use the identity tool for JPA to generate an ID class for entities that use composite primary keys.

• wsenhancer command
  The entity enhancer tool for Java Persistence API (JPA) applications inserts bytecode into an entity class file that supports the JPA provider to manage the state of an entity.

• wsmapping command
  The wsmapping tool is used to provide top-down mapping of the entity object model to the database relational model. We can use the wsmapping tool to create database tables.

• wsreversemapping command
  The wsreversemapping tool generates persistent class definitions and metadata from a database schema.

• wsschema command
  The schema tool can be used to view the database schema in XML form or match an XML schema to an existing database.

• wsdbgen command
  The command supports utilization of the pureQuery feature in Java Persistence API (JPA) applications.

• ANT task WsJpaDBGenTask
  The ANT task WsJpaDBGenTask provides an alternative to the wsdbgen command.

• SQL statement batching for JPA applications
  SQL statement batching can improve the performance of the application server.

• Database generated version ID with JPA
  Java Persistence API (JPA) for WebSphere Application Server has extended OpenJPA to work with database generated version IDs. These generated version fields, timestamp, or token, can be used to efficiently detect changes to a given row.

• Mapping persistent properties to XML columns for JPA
  If the database supports XML column types, we can use mapping tools to manage XML objects. We can map XML columns to a Java string or a Java byte array field.

• Directory conventions
  References in product information to app_server_root, profile_root, and other directories imply specific default directory locations. Become familiar with the conventions in use for WebSphere Application Server.