Recently, I've been working to implement JRuby Embed API. This API is located in the middle layer between JRuby and an embeded application such as JSR 223. I designed this API based on JSR 223 and made it to suit existing JRuby API as much as possible. In addition, I added local, instance, global variables and constant sharing mehcanism, which has been a wishlist for long time.
Today, I put API document on my web site and updated Wiki, which has code examples.
I think JRuby Embed API has a lot of rooms to improve and might be buggy since tests are not enough. However, please give it a try if interesting. I want to know whether this API can satify embedders or not.