Excelsior JET enables you to accelerate your Java applications, to secure them against reverse engineering, to create a complete application setup, and to distribute your Java software products without deployment dependencies such as the Java Runtime Environment (JRE). Yet, you can substantially reduce download size and disk footprint of your Java applications.

Your Java application is delivered in a portable bytecode form and runs on top of the Java Virtual Machine (JVM). The JVM is a part of the JRE that should be installed on every system on which your application runs.

The JVM executes the application and gradually improves its performance by optimizing the Java code at run time.

Put simply, when a user launches your application or a consumer turns on your Java-powered device, Java code performance is relatively low. The performance is improved to some extent only after the application has run for a while. Unfortunately, when it is re-started, the entire warm-up cycle gets repeated.

Suppose you had an automatic tool that optimizes Java code for your target platform before execution. Free of resource constraints inherent to run time optimizers, it processes all the code and optimizes it well.

You feed the application's classes to the tool, which optimizes them for performance and saves the results to disk. Now, you can deploy your Java application in optimized form so that it runs fast from the start on target systems.

What is that automatic tool we are talking about? Read on.

A Java application typically consists of class files and resource files, like images, which are packed into one or more jar files.

Using the Excelsior JET Optimizer, you convert the classes into highly optimized x86 code and create a native executable for Windows or Linux. This technique is called Ahead-Of-Time (AOT) compilation.

Now, the original Java classes are no longer required for the application to run.

And you can launch the executable as you would a native application.

Upon startup, the application executable links to the Excelsior JET Runtime, which provides the Java SE API classes (also native compiled) and low-level runtime support routines necessary for Java applications, such as garbage collection.

Now, your Java application runs directly on the underlying hardware.

Finally, you can leverage Excelsior JET to create a professional installation for the optimized application.

With the help of the Excelsior JET Installation Toolkit, you can create a complete installation package that includes your optimized Java application, the Excelsior JET Runtime, and any additional files, like user's documentation, extra utilities, and so on.

The basic deployment procedure is very simple. The created installation package is a self-contained directory that can be installed on target systems by a simple copy operation. Another option is store it on removable media, such as a flash memory card or USB drive, enabling your end users to run the application without installation.

If necessary, you can wrap the package into Excelsior Installer bundled with Excelsior JET or use another setup generator of your choice.

The JRE need not be installed on target systems for your application to run.

Now you can ship your server-side and desktop Java applications or Java-powered devices to end users.

Your Java application may need to load classes that are available only on a target system, downloaded from a remote host, or generated at run time. Examples are dynamic proxies, third-party plug-ins for your application, and JDBC drivers.

How does Excelsior JET cope with that? Easily.

The Excelsior JET Runtime includes a JIT compiler that transparently loads Java classes to the running application.