difference between SDO and JDO in java

Question

what is the difference between JDO (JSR 243) and SDO (JSR 235) in Java; what set of open source providers are available for these java specifications

Answer 1

From this article:

[...] JDO looks at the persistence issue only [...] whereas SDO is more general and represents data that can flow between any J2EE tier, such as between a presentation and business tier.

EclipseLink is one SDO provider, Apache's DB project is one JDO implementation.