Oracle has released the production version of Helidon 4, a microservices framework for Java featuring a server implementation harnessing virtual threads for higher performance.

Version 4 was announced October 24; instructions can be found at helidon.io. There also is a migration guide. Before Helidon 4, the project’s web server utilized Netty as its foundation and used a reactive API. Release 4 introduces a new server, internally called Nima, designed to harness the capabilities of Java 21 virtual threads. It is intended to reduce the effort needed to write and maintain high-throughput concurrent applications. Using virtual threads is a shift from managing threads as a limited resource to considering them as readily available assets that can be generated on demand to handle an almost limitless number of concurrent requests. Also with Helidon 4, Helidon MP now supports the Eclipse MicroProfile 6.0 enterprise Java microservices architecture.

Java 21 or newer is necessary for using Helidon 4. Helidon is described by proponents as an open source set of cloud-native Java libraries for writing microservices to run on a fast web core, powered by Java virtual threads. There are two flavors: Helidon SE, which provides a microframework model with a small footprint and limited functionality, and Helidon MP, which offers a platform familiar to enterprise Java developers and features a declarative style with dependency injection.