Espresso

Espresso, also known as Java on Truffle, is an implementation of the Java Virtual Machine Specification, built on top of GraalVM. It is a full-fledged Java VM that includes all core components of a VM, implements the same API as the Java Runtime Environment library, and reuses all JARs and native libraries from GraalVM.

Espresso runs Java via a Java bytecode interpreter, implemented with the Truffle framework. Espresso offers benefits like better language isolation and the ability to run different Java versions simultaneously.

Espresso is open source with its codebase accessible on GitHub, and fully supported with this Oracle GraalVM release. (See Oracle GraalVM Support Roadmap.)

Learn more about Java on Truffle from its reference documentation.