Then I have questions: 

1. If make a separate library, where to store library sources? 

2. What about a uniform interface? When exactly will it be implemented? I used existing Jaybird interfaces (FbDatabase, FbStatement, etc) to implement and not to change the existing code, except for the necessary places to fit with the current concept.

Maybe should leave minimal support for the new API, for example, for statements, blobs, etc., as in the existing old JNA?

Vasiliy