Helidon 4 released!

Highlights

Helidon 4 was significantly reworked with some major changes.

No more Netty

Prior to Helidon 4, the Helidon WebServer utilized Netty as its foundation and featured a reactive API. However, in Helidon 4, we introduced a new server implementation, internally known as Níma, which was designed from the ground up to fully harness the capabilities of Java 21’s virtual threads. With virtual threads, we shifted 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.

Since each request now operates within its own dedicated virtual thread, it can freely execute blocking operations, such as interfacing with a database or another service, in a straightforward synchronous manner without the risk of obstructing a platform thread and depriving other requests of resources. This eliminates the necessity for complex asynchronous code to create a low-latency, extremely concurrent service.

The performance is now significantly higher, especially in Helidon MP.

MicroProfile 6.0

Helidon MP now supports MicroProfile 6.0. Learn about MicroProfile 6.0 specifications at https://microprofile.io/.

Please also check the official upgrade guide for Helidon 4 MP.

Blocking APIs

Helidon SE comprises the fundamental set of APIs for Helidon. The significant transformation in Helidon 4 is the adoption of virtual threads, which has facilitated a transition of these APIs from asynchronous to blocking. As a consequence, this shift leads to code that is notably more straightforward to compose, upkeep, troubleshoot, and comprehend. Adapting existing Helidon 3 SE code to function with these updated APIs is necessary, but the investment in this adjustment is certainly justified by the enhanced performance and the increased simplicity of the resulting code.

Please follow the official upgrade guide to learn how to migrate your applications to the new Helidon 4 SE.