Jakarta Persistence (JPA; formerly Java Persistence API) is a

Jakarta EE Jakarta EE, formerly Java Platform, Enterprise Edition (Java EE) and Java 2 Platform, Enterprise Edition (J2EE), is a set of specifications, extending Java SE with specifications for enterprise features such as distributed computing and web se ...

application programming interface specification that describes the management of relational data in enterprise

Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mo ...

applications. Persistence in this context covers three areas: * The API itself, defined in the jakarta.persistence
/code> package ( for Jakarta EE 8 and below) * The

Jakarta Persistence Query Language The Jakarta Persistence Query Language (JPQL; formerly Java Persistence Query Language) is a platform-independent object-oriented query language defined as part of the Jakarta Persistence (JPA; formerly Java Persistence API) specification. JPQL ...

(JPQL; formerly Java Persistence Query Language) * Object/relational metadata The

reference implementation In the software development process, a reference implementation (or, less frequently, sample implementation or model implementation) is a program that implements all requirements from a corresponding specification. The reference implementation ...

for JPA is EclipseLink.

History

The final release date of the JPA 1.0 specification was 11 May 2006 as part of

Java Community Process The Java Community Process (JCP), established in 1998, is a formalized mechanism that allows interested parties to develop standard technical specifications for Java technology. Anyone can become a JCP Member by filling a form available at thJCP we ...

JSR 220. The JPA 2.0 specification was released 10 December 2009 (the Java EE 6 platform requires JPA 2.0). The JPA 2.1 specification was released 22 April 2013 (the Java EE 7 platform requires JPA 2.1). The JPA 2.2 specification was released in the summer of 2017. The JPA 3.1 specification, the latest version, was released in the spring of 2022 as part of Jakarta EE 10.

Entities

A persistence

entity An entity is something that exists as itself, as a subject or as an object, actually or potentially, concretely or abstractly, physically or not. It need not be of material existence. In particular, abstractions and legal fictions are usually r ...

is a lightweight Java class with its state typically persisted to a

table Table may refer to: * Table (furniture), a piece of furniture with a flat surface and one or more legs * Table (landform), a flat area of land * Table (information), a data arrangement with rows and columns * Table (database), how the table data ...

in a

relational database A relational database is a (most commonly digital) database based on the relational model of data, as proposed by E. F. Codd in 1970. A system used to maintain relational databases is a relational database management system (RDBMS). Many relatio ...

. Instances of such an entity correspond to individual rows in the table. Entities typically have relationships with other entities, and these relationships are expressed through object/relational mapping (ORM) metadata. This metadata may be specified directly in the entity class file by using annotations or in a separate

XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. ...

descriptor file distributed with the application.

Example

An example entity class with ORM metadata declared using annotations (import statements and setters/getters are omitted for simplicity). @Entity public class Person The @Entity annotation declares that the class represents an entity. @Id declares the attribute which acts as the

primary key In the relational model of databases, a primary key is a ''specific choice'' of a ''minimal'' set of attributes (columns) that uniquely specify a tuple (row) in a relation ( table). Informally, a primary key is "which attributes identify a record ...

of the entity. Additional annotations may be used to declare additional metadata (for example changing the default table name in the @Table annotation), or to create associations between entities.

Query Language

The

(JPQL; formerly Java Persistence Query Language) makes queries against entities stored in a relational database. Queries resemble SQL queries in syntax but operate against entity objects rather than directly with database tables.

Motivation

Prior to the introduction of

EJB Jakarta Enterprise Beans (EJB; formerly Enterprise JavaBeans) is one of several Java APIs for modular construction of enterprise software. EJB is a server-side software component that encapsulates business logic of an application. An EJB web co ...

3.0 specification, many enterprise Java developers used lightweight persistent objects provided by either persistence frameworks (such as

Hibernate Hibernation is a state of minimal activity and metabolic depression undergone by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It most ...

) or

data access object In software, a data access object (DAO) is a pattern that provides an abstract interface to some type of database or other persistence mechanism. By mapping application calls to the persistence layer, the DAO provides data operations without expo ...

s (DAO) instead of by using entity beans. This is because entity beans, in previous EJB specifications, called for much complicated code and imposed a heavy resource footprint, and they could be used only on Java EE application servers because of interconnections and dependencies in the source code between beans and DAO objects or persistence frameworks. Thus, many of the features originally presented in third-party persistence frameworks were incorporated into the Java Persistence API, and projects such as

and TopLink Essentials have become implementations of the Java Persistence API specification.

Related technologies

Enterprise Beans

The EJB 3.0 specification (itself part of the Java EE 5 platform) included a definition of the Java Persistence API. However, developers do not need an EJB container or a Java EE application server to run applications that use this persistence API. Future versions of the Java Persistence API will be defined in a separate JSR and specification rather than in the EJB JSR/specification. The Java Persistence API replaces the persistence solution of EJB 2.0 CMP (Container-Managed Persistence).

Java Data Objects API

The Java Persistence API was developed in part to unify the Java Data Objects API and the EJB 2.0 Container Managed Persistence (CMP) API. Most products supporting each of the two APIs support the Java Persistence API. The Java Persistence API specifies persistence only for

relational database management system A relational database is a (most commonly digital) database based on the relational model of data, as proposed by E. F. Codd in 1970. A system used to maintain relational databases is a relational database management system (RDBMS). Many relati ...

s by focusing on object-relational mapping (ORM). Some JPA providers support other

database model A database model is a type of data model that determines the logical structure of a database. It fundamentally determines in which manner data can be stored, organized and manipulated. The most popular example of a database model is the relationa ...

s, though this is outside the scope of JPA's design. The introduction section of the JPA specification states: "The technical objective of this work is to provide an object/relational mapping facility for the Java application developer using a Java domain model to manage a relational database." The Java Data Objects specification supports ORM as well as persistence to other types of database models, for example,

flat file database A flat-file database is a database stored in a file called a flat file. Records follow a uniform format, and there are no structures for indexing or recognizing relationships between records. The file is simple. A flat file can be a plain ...

s and

NoSQL A NoSQL (originally referring to "non- SQL" or "non-relational") database provides a mechanism for storage and retrieval of data that is modeled in means other than the tabular relations used in relational databases. Such databases have existed ...

databases, including document databases,

graph database A graph database (GDB) is a database that uses graph structures for semantic queries with nodes, edges, and properties to represent and store data. A key concept of the system is the ''graph'' (or ''edge'' or ''relationship''). The graph relat ...

s any many other datastores.

Service Data Object API

The designers of the Java Persistence API aimed to provide for relational persistence, with many of the key areas taken from object-relational mapping tools such as

and TopLink. Java Persistence API improved on and replaced EJB 2.0, evidenced by its inclusion in EJB 3.0. The Service Data Objects (SDO) API (JSR 235) has a very different objective to that of the Java Persistence API and is considered complementary. The SDO API is designed for

service-oriented architecture In software engineering, service-oriented architecture (SOA) is an architectural style that focuses on discrete services instead of a monolithic design. By consequence, it is also applied in the field of software design where services are provided ...

s, multiple data formats rather than only relational data and multiple programming languages. The

manages the Java version of the SDO API; the C++ version of the SDO API is managed via

OASIS In ecology, an oasis (; ) is a fertile area of a desert or semi-desert environment open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized sof ...

object-relational mapping framework for

. Versions 3.2 and later provide an implementation for the Java Persistence API. King represented

JBoss WildFly, formerly known as JBoss AS, or simply JBoss, is an application server written by JBoss, now developed by Red Hat. WildFly is written in Java and implements the Java Platform, Enterprise Edition (Java EE) specification. It runs on mu ...

on JSR 220, the

JCP