Java Data Objects: Difference between revisions

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'''Java Data Objects''' ('''JDO''') is a specification of [[Java platform|Java]] [[object (computer science)|object]] [[Persistence (computer science)|persistence]]. One of its features is a transparency of the persistent services to the [[___domain model]]. JDO persistent objects are ordinary [[Java (programming language)|Java programming language]] [[class (computer science)|classes]]; there's no requirement for them to implement certain [[interface (Java)|interfaces]] or extend from special classes. JDO 1.0 was developed under the [[Java Community Process]] as [http://www.jcp.org/en/jsr/detail?id=12 JSR 12]. JDO 2.0 was developed under [http://www.jcp.org/en/jsr/detail?id=243 JSR 243] and was released on [[May 10|May 10th]], [[2006]]. JDO 2.1 was completed in Feb 2008, developed by the [http://db.apache.org/jdo/ Apache JDO] project. JDO 2.2 was released in October 2008. JDO 2.3 is in its planning stage.

Object persistence is defined in the external [[XML|XMLs]] metafiles, which may have vendor-specific extensions. JDO vendors provide developers with ''enhancers'', which modify compiled Java class files so they can be transparently persisted. (Note that byte-code enhancement is not mandated by the JDO specification, although it is the commonly used mechanism for implementing the JDO specification's requirements.) Currently, JDO vendors offer several options for persistence, e.g. to [[Relational database|RDBMS]], to [[Object database|OODB]], to [[Computer file|files]].

JDO enhanced classes are portable across different vendors' implementation. Once enhanced, a Java class can be used with any vendor's JDO product.