link creation between Design management and Requirement management using oslc.
One answer
Not quite sure why you need "helpful jars". You can use the OSLC API with all kind of browsers, tools and scripts. Also, I am not quite sure you really mean Rational DOORS Next Generation either, as you asked other question about DOORS Classic. If you do mean RDNG, you can start with the below article.
https://jazz.net/library/article/1197