Introduction to Micronaut presentation delivered by Micronaut creator Graeme Rocher at JBCNConf in Barcelona on the 27th of May 2019

1. Introduction to Micronaut

2. About Me
• Graeme Rocher
• Creator of Grails and Micronaut
• Principal Engineer at Object Computing
• Oracle Groundbreaker Award Winner
• Based in Pais Vasco

3. Agenda
• Challenges Facing Java and Software in General
• Microservces and Serverless vs. Traditional Models
• Micronaut Demos!
• Q & A!

4. Serverless
Challenges
• Challenges to using Java in
Serverless / Microservices scenarios
• Existing Tools and Frameworks Not
Optimized for Cold Starts / Low
Memory
• Go, Node etc. better in this regards
• Tim Bray (Amazon/AWS) and others
not recommending Java
https://youtu.be/IPOvrK3S3gQ?t=1109

5. Adapting to Serverless
• Optimize for cold starts
• Forget about connection pools
• Don't bother with local caches
• Choose technology based on your cold start requirements

6. Adapting to
Microservices
• Cold starts less important, but still
important
• The Container is the deployment
unit
• Containers and Java require special
memory management
• Optimization for memory usage
required

7. Traditional Frameworks
Spring is an amazing technical achievement and does so many
things, but does them at runtime.
• Reads the byte code of every bean it finds
• Synthesizes new annotations for each annotation on each
bean method, constructor, field etc. to support Annotation
metadata
• Builds Reflective Metadata for each bean for every method,
constructor, field etc.

8. What to do, What to
do?
1. Tough technology decisions ahead
2. Choose appropriately tool for the
job
3. Traditional frameworks often not the
best choice

9. The Micro Reality
• Frameworks based on reflection
and annotations become fat
• But we love the programming
model and productivity so
we live with it
• So ... why should we be
more efficient?

12. Java's Problems for
Frameworks
• Limited Annotation API
• Type Erasure
• Slow Reflection
• Reflective Data Caches
• Classpath Scanning
• Slow Dynamic Class Loading

13. Imagine if
Kubernetes or Docker
had been written in
Spring or Jakarta EE
instead of Go?

15. Why is Reflection a Problem?
• Today the JDK is OpenJDK!
• Just take a look...
http://hg.openjdk.java.net/jdk8/jdk8/jdk/file/687fd7c7986d/src/
share/classes/java/lang/Class.java#l2471
• All Reflective data initialized on first access and held in soft
references (yes every field, method etc.)
• Won't be GC'ed until your application is low on memory!

16. Java's "Problems"
• Greatly Exaggerated (Java has been
dead forever)
• Java can be Fast! (see Android and
Micronaut)
• However Most Existing Tools are
based around
• Reflection
• Runtime Proxies
• Runtime Byte Code Generation
(bytebuddy/cglib/javassist)

17. Java's Advantages
• Mature, Robust Ecosystem
• Outstanding IDEs
• Code Maintenance and Refactoring
• Developer Availability
• Build System Maturity
• Diversity (Mobile, IoT, Server Side)
• Languages (Java, Kotlin, Groovy,
Scala)

18. By the time Go has all
the features of Java,
Java's startup
performance will
match Go

19. Already Solved
Problem
• The Android Community already
solved the problem
• Ahead of Time Compilation used
extensively
• Google Dagger 2.x
• Compile Time Dependency
Injector
• Reflection Free
• Limited in Scope to just DI

20. Ahead of Time
Compilation
• So what is Ahead of Time (AOT)
compilation?
• Pre-computation of application code
using closed world static analysis
• Fancy way of saying do more at
compilation time
and less at runtime

22. Micronaut is...
• A Microservices and Serverless
Focused framework (hence the
branding)
• Also a Complete Application
Framework for any type of
Application
• Dependency Injection, Aspect
Oriented Programming (AOP),
Configuration Management,
Bean Introspection and more..

23. Micronaut AOT
Computation
• All Dependency & Configuration
Injection
• Annotation Metadata (Meta
annotations)
• AOP Proxies
• Essentially all framework
infrastructure
• ie. What Spring/CDI do at runtime

24. With Micronaut You
Can Build
• Microservices
• Serverless Applications
• Message-Driven Applications with
Kafka/Rabbit
• CLI Applications
• Even Android Applications
• Anything with
static void main(String..args)

25. So What is
Micronaut? Really?
• An Application Framework for the
Future
• Reflection Free, Runtime Proxy Free,
No Dynamic Classloading
• Ahead of Time (AOT) Compilation
AOT APIs
• ... oh and let's you build
Microservices

26. Micronaut's Impact
• We announced Micronaut on March
2018
• Open Sourced 28th of May 2018 (a
year ago!)
• Sparked industry wide
improvements from Red Hat (with
Quarkus) and Pivotal (Spring Boot
2.2)
• Micronaut is changing the face of
server side Java

27. GraalVM
• A New Universal Virtual Machine
from Oracle
• Features a native-image Tool
• Converts Java -> native machine
code using AOT
• Works well with Micronaut
• Startup time 20ms and Memory
Consumption 18MB!
http://www.graalvm.org

28. DEMOMicronaut

29. Hello Micronaut
@Controller
class HelloController {
@Get("/hello/{name}")
String hello(String name) {
return "Hello " + name;
}
}
@Client("/") // Client Generated at Compile Time
interface HelloClient {
@Get("/hello/{name}")
String hello(String name);
}

30. How Small?
• Smallest Micronaut Hello World JAR is 12MB when written
Java or 14MB in Groovy
• Can be run with as little as 10mb Max Heap with Kotlin or
Java (20mb for Groovy)
• Startup time subsecond for Kotlin or Java (a little more for
Groovy)
• All Dependency Injection, AOP and Proxy generation
happens at compile time

31. Micronaut Microservice
Cold Starts & Memory
Style Cold Start Memory
OpenJDK +/- 800ms +/- 100mb
Eclipse OpenJ9 with
Class Sharing
+/- 300ms +/- 70mb
Graal Native +/- 15ms +/- 15mb

32. Micronaut AWS Lambda
Cold Starts
Style Cold Start
Simple Function +/- 300ms
API Gateway +/- 800ms
API Gateway + Graal Custom
Runtime
+/- 150ms

33. Micronaut 1.1 Out
Now and
Production-Ready
• Compile Time DI & AOP
• HTTP Client & Server
• GRPC and GraphQL Support
• RabbitMQ and Improved Kafka
Support
• Micronaut 1.1.2 supports GraalVM
19 native (experimental status)

34. Micronaut project is
healthy
• ~2 years of development by several
OCI engineers.
• 128 contributors (19 from OCI).
• ~2350 stars on GitHub.
• ~6000 commits.
• More Exciting Announcements in
2019
• Made in Spain (partly ;-)

35. Micronaut Resources
• Gitter Community: https://gitter.im/micronautfw
• User Guide: http://micronaut.io/documentation.html
• Micronaut Guides: http://guides.micronaut.io
• FAQ: http://micronaut.io/faq.html
• Github: https://github.com/micronaut-projects/micronaut-
core
• Examples: https://github.com/micronaut-projects/
micronaut-examples

36. Summary
• Micronaut and GraalVM are leading the AOT revolution
• Server Side Java is Adapting to the Serverless world
• Building more efficient applications possible with right
framework choices
• AOT Sacrifices Compilation Speed to Gain so Much More
• Going native an option for the future with GraalVM

37. Q & AMicronaut