JDO is
- a persistence technology
-allows you to create POJOs (plain old java objects) and persist them to the database
If you are an application programmer, you can use JDO technology to directly store your Java domain model instances into the persistent store (database). Alternatives to JDO include direct file I/O, serialization, JDBC, Enterprise JavaBeans (EJB), Bean-Managed Persistence (BMP) or Container-Managed Persistence (CMP) entity beans, and the Java Persistence API.
http://www.oracle.com/technetwork/java/index-jsp-135919.html
Java Data Objects (JDO) is a specification of Java object persistence. One of its features is a transparency of the persistence services to the domain model. JDO persistent objects are ordinary Java programming language classes (POJOs
persistence has been "broken out" of "EJB3 Core", and a new standard formed, the Java Persistence API (JPA). JPA uses the javax.persistence package
Significantly, javax.persistence will not require an EJB container, and thus will work within a Java SE environment as well, as JDO always has.
JPA, however, is an object-relational mapping (ORM) standard, while JDO is both an object-relational mapping standard and a transparent object persistence standard
JDO, from an API point of view, is agnostic to the technology of the underlying datastore, whereas JPA is targeted to RDBMS datastores (although there are several JPA providers that support access to non-relational datastores through the JPA API, such as DataNucleus and ObjectDB)
http://en.wikipedia.org/wiki/Java_Data_Objects
Apache JDO
Java Data Objects (JDO) is a standard way to access persistent data in databases, using plain old Java objects (POJO) to represent persistent data
The approach separates data manipulation (done by accessing Java data members in the Java domain objects) from database manipulation (done by calling the JDO interface methods).
http://db.apache.org/jdo/
