As of TopLink 11g, TopLink bundles the open source project EclipseLink for most of its functionality.
The TopLink 11g release supports the JPA 1.0 specification. TopLink 10.1.3 also supports EJB CMP and is the persistence provider for OracleAS OC4J 10.1.3 for both JPA and EJB CMP. TopLink provides advanced object-relational mapping functionality beyond the JPA specification, as well as providing persistence for object-relational data-types, and Enterprise Information Systems (EIS/mainframes). TopLink includes sophisticated object caching and performance features. TopLink provides a Grid extension that integrate with Oracle Coherence. TopLink provides object-XML mapping support and provides a JAXB implementation and web service integration. TopLink provides a Service Data Object (SDO) implementation.
TopLink provides a rich user interface through the TopLink Mapping Workbench. The Mapping Workbench allows for graphical mapping of an object model to a data model, as allows for generation of a data model from an object model, and generation of an object model from a data model, and auto-mapping of an existing object and data model. The TopLink Mapping Workbench functionality is also integrated with Oracle's JDeveloper IDE.
TopLink contributed part of its source code to become the JPA 1.0 reference implementation under the Sun java.net Glassfish project. This open-source product is called TopLink Essentials, and despite a different package name (oracle.toplink.essentials) it is basically a branch of the source code of the TopLink product with some advanced functionality stripped out.
TopLink contributed practically its entire source code to the Eclipse Foundation EclipseLink product. This is an open source product currently in incubation that represents the path forward for TopLink. The package name is different (org.eclipse.persistence) but the source code it basically a branch of the TopLink 11g release. Oracle also contributed its Mapping Workbench source code to the project. The TopLink Mapping Workbench developers also were major contributors to the Eclipse Dali project for JPA support.
TopLink was first developed in Smalltalk and ported to Java in the 90's, and has over 15 years worth of object persistence solutions. TopLink originally provided a proprietary POJO persistence API, when EJB was first released TopLink provided one of the most popular EJB CMP implementations, although it continued to recommend its POJO solution. TopLink also provided a JDO 1.0 implementation for a few releases, but this was eventually deprecated and removed once the JPA specification had been formed. Oracle and TopLink have been involved in each of the EJB, JDO and EJB3/JPA expert groups, and Oracle was the co-lead for the EJB3/JPA specification.