The existing JDBC API leads to blocked threads, threads scheduling, and contention. For high throughput and large-scale deployment, the Java community needs a standard asynchronous API for database access where user threads never block.
ADBA is Asynchronous Database Access, a non-blocking database access API that Oracle is proposing as a Java standard. It is not intended to be an extension to, or a replacement for, JDBC but, rather, an entirely separate API that provides completely nonblocking access to the same databases as JDBC.
The ADBA source is available for download from the OpenJDK sandbox as part of the OpenJDK project. You can get involved with the project by reviewing the API and providing feedback on the JDBC mailing list