Firebase is a game agnostic, high availability, scalable platform for multiplayer online games written in Java.
You code your game against the API and deploy it to the server much like you would do with a Web application.
Open source project that offer summary and download services on this page is a project that carry out their development work on other open source development sites. Their work is linked to this page via a feature called OFI, and their work is not carried out here on OSDN site.