Oracle TopLink

The runtime component of TopLink is provided by the EclipseLink Core. This API provides direct access to the runtime, which is embedded into the application. Persistence behavior is enabled by making application calls that invoke EclipseLink API to perform these functionalities which provides safe access to shared databases.[3]

Import the following class to use extended functionality of EclipseLink.

import org.eclipse.persistence.*

The binding of Java classes to XML schemas is possible with the help of Object-XML, which is an EclipseLink component. By implementing JAXB, mapping information is provided through annotations. It also provides manipulation of XML.[3]

The Service Data Objects (SDO) provides with the use of SDO API, use dynamic objects to customize and manipulate XML, use of static data objects and conversion of XML Schema.[3]

Database Web Services (DBWS) facilitates access to relational databases with the help of web service. A database access can be made without the need to write a Java code. The XML SOAP Messages and the databases are connected by the runtime component of DBWS which uses EclipseLink.[3]

TopLink Grid is an integration mechanism that provides connection between Oracle Coherence and EclipseLink. An application generally interacts with the relational database, which is its primary database. But with TopLink the application can store data on the Coherence grid called as JPA on the grid.[4]

TopLink Grid functionality can be used only if the user has license for Oracle Coherence. This functionality is provided by:

toplink-grid.jar

To get support for TopLink Grid and EclipseLink, users also need to import the following package of classes.

org.eclipse.coherence.*

The EntityManager method persist(Object entity) is used to add an instance and marks it for insertion into the database.

entityManager.getTransaction().begin(); 
Employee newEmployee = new Employee(5); 
entityManager.persist(newEmployee); 
entityManager.getTransaction().commit();

On completion of the transaction, the newEmployee data will be inserted into the database.[5]

Updating an entity means simply reading the transaction and updating the properties of this entity. Updating the Employee LastName can be done as follows.[5]

entityManager.getTransaction().begin(); 
Employee existingEmployee = entityManager.find(Employee.class, 5); 
existingEmployee.setLastName("NewLastName"); 
entityManager.getTransaction().commit();

Deleting an entity is the opposite of Insertion and can be one using remove(Object entity) method of the EntityManager.

entityManager.getTransaction().begin(); 
Employee existingEmployee = entityManager.find(Employee.class, 5); 
entityManager.remove(existingEmployee); 
entityManager.getTransaction().commit();

The EntityManager method flush() deletes the entity on completion of the transaction.[5]