Have you ever wanted to run a Java application right on the metal, without concern for an OS? If you're developing a dedicated appliance or embedded system, even one with server-style capabilities, this can be very desirable. Oracle-BEA offers a product called LiquidVM (http://www.bea.com/framework.jsp?CNT=index.jsp&FP=/content/solutions/virtualization/), which is based on the BEA JRockit JVM (http://www.bea.com/framework.jsp?CNT=index.htm&FP=/content/products/weblogic/jrockit/), that runs right on a hypervisor (http://en.wikipedia.org/wiki/Hypervisor), without the need for an OS.
This also implies that the box running LiquidVM (and the lower-lever hypervisor) can run no other applications besides the one running in the JVM. This may actually be desirable for embedded systems and appliances, where simplicity and raw performance are important qualities.
Take a look at Oracle-BEA's description of LiquidVM:
LiquidVM provides the following features:
- JRockit JVM as the Java runtime component.
- Java run-time class libraries.
- A scaled-down OS kernel that replaces the OS for LiquidVM. It differs from a normal OS in that it is a single-user, single-process environment that is designed to only run a single JVM. No other processes can be started. It implements the following services that the JRockit JVM needs to run Java:
- Java-based services, started after the JRockit JVM has started, that run in threads that are separate from your application. The LiquidVM services are:
- Tools that are used to create and control LiquidVM instances. The LiquidVM tools run on a standard OS; they do not run inside LiquidVM. LiquidVM tools include:
- A virtual local disk for each WLS-VE instance. The local disk removes the dependence on NFS and provides faster and more secure file transfers
For a full description, go to http://e-docs.bea.com/wl-ve/docs10-x/config/lvmintro.html.