Apache ObJectRelationalBridge (OJB) is an Object/Relational mapping tool that allows transparent persistence for

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 ...

Objects against

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 ...

s. It was released on April 6, 2005. As of January 16, 2011 Apache ObJectRelationalBridge has been retired.Apache ObJectRelationalBridge (OJB)
Apache Software Foundation.

Features

OJB is an ''

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 ...

'' project. It is lightweight and easy to use, requiring simply configure two files to implement a persistence layer. It is easy to integrate into an existing application because it does not generate code. It allows the use of different patterns of persistence: owner (PersistenceBroker

API An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how ...

), JDO and Object Data Management Group (

ODMG The Object Data Management Group (ODMG) was conceived in the summer of 1991 at a breakfast with object database vendors that was organized by Rick Cattell of Sun Microsystems. In 1998, the ODMG changed its name from the Object Database Management Gr ...

Functionality

OJB uses an

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. ...

based Object/Relational mapping. The mapping resides in a dynamic MetaData layer, which can be manipulated at runtime through a simple Meta-Object-Protocol (MOP) to change the behaviour of the persistence kernel.

Configuration

At least two files are required to configure OJB: OJB.properties and repository.xml

Allocation

For mapping a 1-1 relationship, for example, you have two tables: person and account. In this case, a person has an account and vice versa.

References

External links

Apache ObJectRelationalBridge

OJB Apache ObJectRelationalBridge (OJB) is an Object/Relational mapping tool that allows transparent persistence for Java Objects against relational databases. It was released on April 6, 2005. As of January 16, 2011 Apache ObJectRelationalBridge has ...