Developer Experience in a Modern Java Framework

Micronaut is a modern, JVM-based, full stack Java framework designed for building modular, easily testable JVM applications.

Developed since 2018 by the creators of the Grails framework, Micronaut takes inspiration from lessons learnt over more than 10 years building frameworks and developer tools.

In this talk, Micronaut committer Álvaro Sánchez-Mariscal, will demonstrate with a live coding session the developer experience of a Micronaut user through features like:
- Sub-second startup times.
- Instantaneous functional testing including injection of any bean.
- First-class support for Testcontainers for both development and testing via Micronaut Test Resources.
- Declarative HTTP clients with HTTP contracts via Java interfaces.
- Source code compile-time checks for faster feedback.
- Advanced annotations for bean requirements, replacements and fallbacks.
- Type-safe, validated configuration system.
- Batteries-included packaging options, including JAR, Docker and GraalVM native image formats.
- Control Panel, the Micronaut development UI.

Transcript

1. Developer experience in a modern Java framework Álvaro Sánchez-Mariscal Principal Member of Technical Staff Oracle @alvaro_sanchez
2. Copyright © 2024, Oracle and/or its affiliates 2 About me • Coming from Madrid • Developer since 2001 (Java stack) • Micronaut core developer since its inception (2017). • Author: Maven Plugin, Object Storage, Kubernetes, Cache, Control Panel. • Others: Core, Gradle, AWS, GCP, Azure, Security, Test, etc. • Currently at Oracle Labs: • Micronaut and Graal Development Kit for Micronaut (GDK). • GraalVM Native Build Tools. @alvaro_sanchez
3. Slides available on Speaker Deck 3 Copyright © 2024, Oracle and/or its affiliates
4. Copyright © 2024, Oracle and/or its affiliates. Micronaut® is a registered trademark of Object Computing, Inc. Use is for referential purposes and does not imply any endorsement or affiliation with any third-party product. 4
5. Introduction to Micronaut Copyright © 2024, Oracle and/or its affiliates 5 Micronaut is a complete solution for any type of application: microservices, message-driven producers or consumers, command-line apps, serverless functions, etc. All application types Micronaut leverages Java annotation processors and other optimisations to compute the framework infrastructure at compile-time, drastically reducing startup time and memory consumption. Highly optimised Modern, open-source Java Framework Micronaut has been designed from scratch in 2017, focused on modern architectures like microservices and serverless, and with the cloud in mind.
6. Micronaut computes at build time: • All dependency and configuration injection. • Annotation metadata (meta annotations) • AOP proxies. • Bean introspections. • All other framework infrastructure. At runtime: • No reflection. • No proxy generation. • No dynamic classloading. • No classpath scanning. AOT: Ahead Of Time Copyright © 2024, Oracle and/or its affiliates 6 Source code @Singleton class MySvc {} Bytecode class $MySvc$Definition {} class $MySvc$Definition$Reference {} Source code @Builder record Person() {} Source code @Generated class PersonBuilder() {} compilation compilation
7. 7 Any language, build tool, test framework, reactive library, cloud, … Copyright © 2024, Oracle and/or its affiliates
8. Micronaut Hello World 8 Copyright © 2024, Oracle and/or its affiliates
9. Micronaut features: HTTP Client 9 Copyright © 2024, Oracle and/or its affiliates Implemented at compile time
10. Micronaut features: message-driven applications Kafka • Producers. • Consumers. • Kafka Streams. RabbitMQ • Producers. • Consumers. • RPC. MQTT • Publishers. • Subscribers. NATS • Producers. • Consumers. Copyright © 2024, Oracle and/or its affiliates 10
11. Micronaut features: data access 11 Copyright © 2024, Oracle and/or its affiliates
12. Micronaut features: data access 12 Copyright © 2024, Oracle and/or its affiliates Interface implemented at compile time Query generated from the method name, compile-time validated Can have custom queries, inserts, etc
13. Micronaut unique features: Test Resources 1. Automatic provisioning of external resources needed during development or testing. • Containers, binaries, etc. 2. Built-in support: 3. Integrated with JUnit Platform (JUnit / Spock / Kotest) for zero-configuration Testcontainers. 13 Copyright © 2024, Oracle and/or its affiliates • MariaDB • MySQL • Oracle • PostgreSQL • SQL Server • Elasticsearch • Redis • MongoDB • Neo4j • Hashicorp Vault • Kafka • RabbitMQ • MQTT • Localstack
14. Micronaut unique features: Serialization 1. Drop-in replacement for Jackson Databind, compile-time and reflection free. 2. Supports (most of) Jackson, JSON-B and BSON annotations. 3. Why? • Memory performance: 10x smaller runtime footprint. • Security: serializable classes must be opt-in. • Type-safety: Micronaut Serialization performs checks at compile-time (vs Jackson runtime exceptions). • Runtime portability: Micronaut Serialization at runtime supports different annotation sets. 14 Copyright © 2024, Oracle and/or its affiliates
15. Micronaut unique features: Validation 1. Built-in alternative for Jakarta Bean Validation. • Spec features that require reflection are not supported. • Use Hibernate Validator if needed. 2. Supported universally across the framework. • Configuration classes, entities, controllers, etc. 3. Benefits: • Reflection and runtime proxy free. • Smaller footprint (1.4MB less). • Faster startup (200+ ms less). • Compile-time validation. • GraalVM support out of the box. 15 Copyright © 2024, Oracle and/or its affiliates
16. Getting Started: Micronaut Guides 16 Copyright © 2024, Oracle and/or its affiliates https://guides.micronaut.io
17. Getting Started: Micronaut Launch 17 Copyright © 2024, Oracle and/or its affiliates https://launch.micronaut.io
18. Getting Started: Micronaut CLI 18 Copyright © 2024, Oracle and/or its affiliates
19. Getting Started: Intellij IDEA 19 Copyright © 2024, Oracle and/or its affiliates
20. Getting Started: Visual Studio Code 20 Copyright © 2024, Oracle and/or its affiliates
21. Graal A full stack for the development and deployment of high performance Java cloud native applications
22. Copyright © 2024, Oracle and/or its affiliates 22
23. What is Graal Development Kit for Micronaut? Copyright © 2024, Oracle and/or its affiliates 23 BUILT FOR GRAALVM NATIVE IMAGE Easily compile ahead-of-time with GraalVM Native Image into small executables that start instantly, and use less memory/CPU. CLOUD-AGNOSTIC MODULES A curated set of Micronaut modules that provide platform-independent support for core cloud services – object store, secrets, streaming, and more. DEV TOOLS AND VS CODE EXTENSIONS Dev tools to generate multicloud application starter templates. VS Code extensions for local development and cloud deployment.
24. 24 Copyright © 2024, Oracle and/or its affiliates
25. 25 Copyright © 2024, Oracle and/or its affiliates
26. Copyright © 2024, Oracle and/or its affiliates 26
27. What is GraalVM 27 Copyright © 2024, Oracle and/or its affiliates
28. Native Image Goals Low Resource Usage Start Fast Compact Packaging Minimize Vulnerability Copyright © 2024, Oracle and/or its affiliates 28
29. Micronaut and GraalVM 6ms As low as startup time 18MB Consuming memory footprint >30% Increased throughput up to and reduced latency
30. Micronaut and GraalVM 1. The best integration possibly, supported by teams working together at Oracle Labs. • GraalVM EE includes optimisations for Micronaut for increased performance and throughput. • GraalVM EE license included in Oracle Cloud. 2. Micronaut is ready for GraalVM Native Image since day 1. • No reflection, no runtime proxies, no bytecode generation, no dynamic classloading. 3. GraalVM tooling for Visual Studio Code and Intellij IDEA. 30 Copyright © 2024, Oracle and/or its affiliates
31. GraalVM Reachability Metadata Repository Community-driven collection of GraalVM reachability metadata for open-source libraries. • Actively maintained by a collective effort of VMware, Oracle and others. • Enabled in GraalVM Native Build Tools (Maven and Gradle plugins). • Integrated by default in Spring Boot and Micronaut. 31 Copyright © 2024, Oracle and/or its affiliates
32. Micronaut is the fastest to startup 32 Copyright © 2024, Oracle and/or its affiliates Source: https://speakerdeck.com/mraible/comparing-native-java-rest-api-frameworks-jchampions-conference-2024
33. Micronaut is the fastest to startup 33 Copyright © 2024, Oracle and/or its affiliates Source: https://speakerdeck.com/mraible/comparing-native-java-rest-api-frameworks-jchampions-conference-2024
34. Micronaut consumes the less memory 34 Copyright © 2024, Oracle and/or its affiliates Source: https://speakerdeck.com/mraible/comparing-native-java-rest-api-frameworks-jchampions-conference-2024
35. Micronaut and GraalVM powering Disney+ 35 Copyright © 2024, Oracle and/or its affiliates https://aws.amazon.com/blogs/opensource/improving-developer-productivity-at-disney-with-serverless-and-open-source/
36. Copyright © 2024, Oracle and/or its affiliates 36 Demo Micronaut and GraalVM
37. Álvaro Sánchez-Mariscal @alvaro_sanchez
38. Copyright © 2024, Oracle and/or its affiliates 38 Q &A