The Nest system is written in Java and the Java Virtual Machine (JVM) has to be installed on the user's computer. The recommended version of JVM can be downloaded from the http://www.java.com.
To launch Nest the Java Web Start is used:
Applications launched with Java Web Start are – by default – run in a restricted environment where they have limited access to the local computing resources, such as storage devices and the local network. If an application needs to access local resources (like Nest does) it should be digitally signed. Nest is under development and developers do not provide any guarantees. You can run it at you own risk.
Apple has enforced security policies in their latest update of Mac OS X 10.8.4, which no longer allows users to auto-launch JNLP files. Attempting to launch JNLP files generates the error message like:
"The Gatekeeper feature, introduced in Mountain Lion (OS X 10.8), allows users to set the level of security for downloaded applications. By default, Gatekeeper is set to allow only OS X App Store and Developer ID signed applications. Unless your app is signed with a Developer ID certificate provided by Apple, your application will not launch on a system with Gatekeeper's default settings." - www.oracle.com