The PingDirectory server requires Java. For optimized performance, use Java for 64-bit architectures. See System requirements for the list of supported Java versions.
Even if your system already has Java installed, you might want to create a separate Java installation for use by the PingDirectory server so that updates to the system-wide Java installation do not impact the server.
A separate Java installation requires that you download the Java Development Kit (JDK) instead of the Java Runtime Environment (JRE) for the 64-bit version.
To install Java, go to the website for the type of Java you want to install, locate the preferred version, and follow the instructions.