NoSQL is a classification of database systems that do not conform to the relational database or SQL standard. They have various roots, from distributed internet databases, to object databases, XML databases and even legacy databases. They have become recently popular because of their use in large scale distributed databases in Google, Amazon, and Facebook.
There are various NoSQL databases including:
- Mongo DB
- Oracle NoSQL
- Google BigTable
- Couch DB
As of EclipseLink 2.4, EclipseLink has added JPA support for NoSQL databases, initially with support for MongoDB and Oracle NoSQL.
EclipseLink's NoSQL support allow the JPA API and JPA annotations/xml to be used with NoSQL data. EclipseLink also supports several NoSQL specific annotations/xml including @NoSQL that defines a class to map NoSQL data.
EclipseLink's NoSQL support is based on previous EIS support offered since EclipseLink 1.0. EclipseLink's EIS support allowed persisting objects to legacy and non-relational databases. EclipseLink's EIS and NoSQL support uses the Java Connector Architecture (JCA) to access the data-source similar to how EclipseLink's relational support uses JDBC. EclipseLink's NoSQL support is expendable to other NoSQL databases, through the creation of an EclipseLink EISPlatform class and a JCA adapter.
This example shows how to map and persist an Ordering system object model to a MongoDB NoSQL database.