Java Data Objects (JDO)

Transparent Persistence and JDO

Gopalan Suresh Raj

JDO enables Java developers to store their Java objects in a transactional data store without the need to explicitly manage the storage and retrieval of individual fields. Java Serialization also provides a similar mechanism.

Both JDO and Java Serialization enable an entire graph of related objects to be stored with one call once one of the objects is specified to be persistent. With serialization, the entire graph can be retrieved with a single call. However, JDO extends this by allowing individual objects in the graph and individual fields in those objects to be retrieved separately.

Persistence by Reachability (PBR) which is "the closure of instances of persistence-capable classes reachable from persistent fields will be made persistent at commit time" is one of the primary features of Transparent Persistence which includes features like

Change tracking and automatic enlistment
Persistence By Reachability
Lazy data loading
Automatic navigation of the object graph.
 

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