Eclipse JNoSQL Communication, Diana, is a flexible and extensible API to connect NoSQL databases. It
brings an easy interface to
support key-value, column family, document oriented and graph databases as JDBC is for SQL databases
Download JD-GUI to open JAR file and explore Java source code file (.class .java)
Click menu "File → Open File..." or just drag-and-drop the JAR file in the JD-GUI window diana-api-0.0.9.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.