Excelsior delivers embedded Java SE run time and development tools like its latest Excelsior JET platform. It includes ahead-of-time (AOT) compiler and installation toolkit that has passed the Java Compatibility Kit (JCK) test suite,
Excelsior JET generates native x86 applications providing its own run time support. It is compatible with Java SE but does not require the Oracle JRE. In addition to the compiler, JET includes the Java Control Panel configuration tool (Fig. 1) that allows tuning of a range of features including garbage collection.
Excelsior does not include a hard real time garbage collector. It is faster in worst case of than Oracle's HotSpot platform. JET employs a hybrid garbage collection scheme that allows some parallelism in the various collection phases.
The system provides a range of optimizations including the Start Up Optimizater that minimizes an already improved start up process by reducing scattered access to code. The AOT support already means that code does not have to be compiled like the HotSpot environment requires.
Excelsior JET's packaging system includes support for the Java Runtime Slimdown optimizer that eliminates unused code including from the run time support (Fig. 2). This includes code within standard libraries like Swing or AWT. For example, an application that does not utilize graphics can be substantially reduced. The system can also get rid of unused fonts.
Excelsior JET is available in four editions. The Standard Edition provides basic native code support. The Professional Edition targets professional developer requiring maximum optimization for improved application performance and reduced download size. This includes support for the global optimizer. The Enterprise Edition adds support for multiprocessor servers.It also has special support for OSGi and Apache Tomcat, providing a protected environment for running Eclipse RCP applications and Web applications. The original class files are not required at run time despite the use of custom classloaders.
The Excelsior JET Embedded version is designed for embedded applications and includes most features found in the Professional Edition. It targets Windows and Linux platforms.
All but the Standard Edition support the optimizing Just-In-Time (JIT) compiler in addition to AOT code. The Standard Edition has the non-optimizing JIT compiler. This allows dynamic loading of Java classes. Excelsior JET includes a JIT caching engine that saved JITed code to disk.
The latest version is compatible with Java SE 6. It is possible to create an installer for Windows-based Java applications. It is even possible to create trial versions of your applications.