Plug-in Architectures With Layrry and the Java Module System (vJUG)

-- A joint talk with Andres Almiray at Virtual JUG --

The Java Module System lays the foundation for building modularized applications on the JVM. It doesn’t concern itself though with resolving module versions and obtaining modules from repositories.

This is where Layrry comes in: an API and launcher for modularized Java applications which takes a descriptor of the module layer(s) to assemble, fetches the modules and starts up the application.

Join us for this session and learn how to:

* Build Java applications using layers, e.g. providing isolation between different versions of one module.
* Use jbang to launch your layered apps in no time.
* Create plug-in based rich-client applications using JavaFX and Layrry, allowing to – dynamically reconfigure and update your layer hierarchy, no restarts required.
* Create your own customized Layrry launcher if needed

This session is code-centered, be ready to see the Java Module System, Layrry, and JavaFX in action!

Transcript

1. @gunnarmorling | @aalmiray #Layrry Plug-in Architectures With Layrry and the Java Module System Gunnar Morling | Andres Almiray
2. @gunnarmorling | @aalmiray #Layrry Gunnar Morling • Open source software engineer at Red Hat ◦ Debezium ◦ Hibernate • Spec Lead for Bean Validation 2.0 • Java Champion • @gunnarmorling
3. @gunnarmorling | @aalmiray #Layrry Andres Almiray • Senior Principal Product Manager @ Oracle ◦ “Seasoned Sourceror” • ❤ Open Source & Java • Apache Groovy PMC • Java Champion Alumni • @aalmiray
4. @gunnarmorling | @aalmiray #Layrry JPMS Java Platform Module System (also known as Jigsaw) Introduced in Java 9 Designed to break down the JVM monolith Applicable to user space as well The promise is to give developers better code encapsulation and design foundations
5. @gunnarmorling | @aalmiray #Layrry However... © Alexander Henning Drachmann https://flic.kr/p/uUA4G (CC BY-SA 2.0)
6. @gunnarmorling | @aalmiray #Layrry Some User Statements “JPMS only allows for one version of a module” “JPMS doesn’t allow to add modules at runtime” “I have to modularize ALL my dependencies in order to benefit from JPMS” “It’s so hard to map dependency coordinates to module dependencies” “Help, non-exported packages of different modules collide!”
7. @gunnarmorling | @aalmiray #Layrry What no one ever said “Let’s use JPMS Layers to tackle (some of) these issues”
8. @gunnarmorling | @aalmiray #Layrry Module Layers https://docs.oracle.com/en/java/javase/14/docs/api/java.base/java/lang/ModuleLayer.html
9. @gunnarmorling | @aalmiray #Layrry Using the Layers API
10. @gunnarmorling | @aalmiray #Layrry Hello, Layrry! An API and Launcher for Modularized Java Applications
11. @gunnarmorling | @aalmiray #Layrry Hello, Layrry!
12. @gunnarmorling | @aalmiray #Layrry Layrry JPMS © Christoper Michel https://flic.kr/p/UMtHv5 (CC BY 2.0)
13. @gunnarmorling | @aalmiray #Layrry Ready-Made Launcher layrry-launcher-<version>-all.jar \ —layers-config layers.yml
14. @gunnarmorling | @aalmiray #Layrry Parameterization
15. @gunnarmorling | @aalmiray #Layrry Built-in Template Support layrry-launcher-<version>-all.jar \ —layers-config javafx.toml \ —properties versions.properties
16. @gunnarmorling | @aalmiray #Layrry jbang layrry@moditect \ —layers-config javafx.toml \ —properties versions.properties
17. @gunnarmorling | @aalmiray #Layrry Local Repositories © Andres Almiray (CC BY 2.0)
18. @gunnarmorling | @aalmiray #Layrry Local Repositories • Artifacts can be organized in a local repository that does not require remote resolution • Two layouts currently supported
19. @gunnarmorling | @aalmiray #Layrry Local Repositories
20. @gunnarmorling | @aalmiray #Layrry Local Repositories
21. @gunnarmorling | @aalmiray #Layrry Plug-in Architectures © Justin Taylor https://flic.kr/p/4fQz9t (CC BY 2.0)
22. @gunnarmorling | @aalmiray #Layrry Plug-in Architectures Can dynamically add (and remove) layers at runtime
23. @gunnarmorling | @aalmiray #Layrry Plug-in Architectures
24. @gunnarmorling | @aalmiray #Layrry © Bob Adams https://flic.kr/p/cYV7gq (CC BY-SA 2.0) Demo
25. @gunnarmorling | @aalmiray #Layrry Bonus: Class Unloading • Classes and layer class loader subject to GC after plug-in removal • Dragons beware, class loader leaks can happen ◦ Dangling references in remaining layers ◦ Started threads ◦ Shutdown hooks
26. @gunnarmorling | @aalmiray #Layrry
27. @gunnarmorling | @aalmiray #Layrry
28. @gunnarmorling | @aalmiray #Layrry
29. @gunnarmorling | @aalmiray #Layrry
30. @gunnarmorling | @aalmiray #Layrry Outlook • Remote layer files • Binary distributions: Github Releases, Homebrew, SDKMan, etc. • Integration with jlink • Derive layers from pom.xml? • Programmatic plug-in API • Your contributions?!
31. @gunnarmorling | @aalmiray #Layrry Resources Source code https://github.com/moditect/layrry https://github.com/moditect/layrry-examples
32. @gunnarmorling | @aalmiray #Layrry Resources Blog posts https://www.morling.dev/blog/introducing-layrry-runner-and-api-for- modularized-java-applications/ https://www.morling.dev/blog/plugin-architectures-with-layrry-and- the-java-module-system/ https://www.morling.dev/blog/class-unloading-in-layered-java-applications/
33. @gunnarmorling | @aalmiray #Layrry Q & A
34. @gunnarmorling | @aalmiray #Layrry Demo
35. @gunnarmorling | @aalmiray #Layrry JavaFX Demo