Fantastic Java contracts - and where to define them

Creating objects in Java using new keyword was a no brainer for many years! Then IoC / DI questioned the approach and component containers changed the way we think about it! Managing dependencies between artifacts is yet another topic we still tend to think we have sorted out. Maven central has become the de facto standard artifact repository. Yet it's far from perfect as it is still developer's responsibility to know and configure proper dependencies. This easily becomes nightmare with transitive and provided dependencies. So may be it's time to challenge that approach too? What if we move from hardcoded artifacts to artifact discovery based on well defined contracts? This talk will demonstrate how that can be done today, what are the issues and draft a potential roadmap to fully automated dependency management!

Transcript

1. Fantastic Java Contracts and where to define them? @MilenDyankov Developer Advocate, Liferay
2. Liferay Platform Marketplace Sync Screens Mobile SDK Faces AlloyEditor Liferay IDE AlloyUI Lexicon Electric Senna.js Metal.js Deploy
3. Once upon a time there was new Keyword();
4. Once upon a time there was new Keyword(); Then the spring brought us some <beans>
5. Once upon a time there was new Keyword(); Then the spring brought us some <beans> Today we have @Components
6. It was not about writing code easier or faster! It was opening the door for a whole new world of possibilities!
7. Once upon a time there were libs and deps folders
8. Once upon a time there were libs and deps folders Then Maven brought us <dependencies>
9. It was about easier and faster! It didn’t change the way we think about dependencies, it changed the way we store and distribute them!
10. Dependency hell
11. Dependencies They can be transitive, but it’s still us developers solving the conflicts!
12. Dependencies They can have version ranges but it’s still us developers to know which SLF4J logger finally goes to production!
13. Dependencies They have scopes but it’s still us developers to decide what is provided by containers, runtimes and systems!
14. Dependencies They define relationships between each other but not to external resources like runtime, OS, infrastructure, ...
15. Dependencies They tell you NOTHING about WHY they depend on each other!
16. box box Dependencies as we see them! Depends on
17. item item Dependencies as they are Depends on box box
18. item item Requirements and Capabilities inspect create inspect create box box I have
 XYZ I need
 XYZ
19. item item Requirements and Capabilities inspect create inspect create box box I have
 XYZ I need
 XYZ No dependencies but contracts
20. Live DEMO https://github.com/azzazzel/Fantastic-Java-Contracts-Demo
21. calc API markup simple
 calc editor depends depends depends
22. calc API markup simple
 calc editor depends depends depends depends
23. calc API markup simple
 calc editor depends depends depends depends
24. calc API markup simple
 calc editor depends depends depends depends
25. calc API markup simple
 calc editor another
 calc calculator
 panel depends depends depends depends depends depends depends
26. calc API markup simple
 calc editor depends depends depends
27. calc API markup simple
 calc editor Contractors
 repository simple-calc . . . I require calc implementation I provide calc implementation depends depends depends resolve
28. calc API markup simple
 calc editor Contractors
 repository simple-calc . . . I require calc implementation I provide calc implementation depends depends depends resolve another
 calc I provide calc implementation depends
29. Eccentric Modularity https://github.com/commsen/EM
30. module JAR contractor I provide …. I require …. I provide …. Maven Central JAR contractor I provide …. I require …. module I provide ….
31. module JAR contractor I provide …. I require …. I provide …. Maven Central Contractors
 repository Prepare 
 (optional) mvn em:addContractors … JAR contractor I provide …. I require …. module I provide ….
32. contractor A
 contractor B
 ... 
 module M1
 module M2 module JAR contractor I provide …. I require …. I provide …. module I provide …. Maven Central Contractors
 repository Prepare 
 (optional) mvn em:addContractors … JAR contractor I provide …. I require …. Build mvn package … module I provide …. module I require …. hint modular
 runtime I provide ….
33. module JAR contractor I provide …. I require …. I provide …. module I provide …. Maven Central Contractors
 repository Prepare 
 (optional) mvn em:addContractors … JAR contractor I provide …. I require …. Build mvn package … module I provide …. hint module module module … deploy contractor A
 contractor B
 ... 
 module M1
 module M2 modular
 runtime I provide …. module I require ….
34. Thank you! @MilenDyankov Developer Advocate, Liferay