Refactoring your Application to Data Oriented Programming

You can find the GitHub repo for this lab here: https://github.com/JosePaumard/2025_JavaOne-DOP-Amber-lab

Data Oriented Programming is a programming model, that is being implemented in Java in a step by step approach. It allows you to organize your application differently than what Object Oriented Programming does. It uses several of the features added by the Amber project: sealed types, exhaustive switch expressions on types, records, and pattern matching. It is still a work in progress, as pattern matching is still being developped, but all the other elements are available as final features. This hands-on lab gives you a simple application as a starting point, developped following the Object Oriented Programming principles. You will then be guided step by step through the refactoring, following the principles of Data Oriented Programming. By the end of this workshop, you will gain a better understanding of Data Oriented Programming, and how and where you can apply its principles in your application.

Transcript

1. Refactoring your Application to Data Oriented Programming The Amber Project José Paumard Java Developer Advocate Java Platform Group Billy Korando Senior Developer Advocate Java Platform Group
2. @billykorando.bsky.social billy.korando@oracle.com https://dev.java
3. @josepaumard.bsky.social https://dev.java
4. 3/21/2025 Copyright © 2025, Oracle and/or its affiliates 4 https://dev.java/
5. 3/21/2025 Copyright © 2025, Oracle and/or its affiliates 5 Tune in! Inside Java Newscast JEP Café Road To 21 series Inside.java Inside Java Podcast Sip of Java Cracking the Java coding interview
6. https://marketplace.eclipse.org/content/java-24-support-eclipse-2025-03-435
7. https://www.jetbrains.com/idea/download/
8. 3/21/2025 Copyright © 2025, Oracle and/or its affiliates 8 https://bit.ly/javaone25-dop-lab javaone25 javaturns30
9. 3/21/2025 Copyright © 2025, Oracle and/or its affiliates 9 Structure of the Lab
10. 3/21/2025 Copyright © 2025, Oracle and/or its affiliates 10 Is it new? The Expression Problem: how to extend statically typed data abstractions, in representations and behavior, without having to recompile the existing code. User-defined Types and Procedural Data Structures as complementary approaches to Data Abstraction." Reynolds, John C. (1975). . New Directions in Algorithmic Languages (PDF). IFIP Working Group 2.1 on Algol. pp. 157–168. Foundations of Object-Oriented Languages (FOOL), Cook, William (1990), REX School/Workshop. Lecture Notes in Computer Science. Vol. 489. Noordwijkerhout. Data Oriented Programming
11. 3/21/2025 Copyright © 2025, Oracle and/or its affiliates 11 Polymorphism - Add new subtypes - No new operations Wadler’s Answer Pattern Matching - Add new operations - No new subtypes You cannot get both  If you are not the owner of the code: Phil Wadler
12. 3/21/2025 Copyright © 2025, Oracle and/or its affiliates 12 Because it has to do with long term maintenance of your applications When your business requirements evolve: 1) How can you add behavior to your Object Model? 2) Can you remove the behavior that becomes obsolete? Why is This Problem Interesting?
13. 3/21/2025 Copyright © 2025, Oracle and/or its affiliates 13 Structure of the Lab: Step 0 3 types of relationship: 1) Push 2) Pull 3) Pubsub A_Database B_Price-monitoring C_GUI D_Fligt-BP
14. 3/21/2025 Copyright © 2025, Oracle and/or its affiliates 14 Structure of the Lab: Step 1 3 types of relationship: 1) Push 2) Pull 3) Pubsub A_Database B_Price-monitoring C_GUI D_Fligt-BP
15. 3/21/2025 Copyright © 2025, Oracle and/or its affiliates 15 Fixing the Application / DB Relation DB FlightEntity (Hibernate) Business Module
16. 3/21/2025 Copyright © 2025, Oracle and/or its affiliates 16 Fixing the Application / DB Relation DB FlightEntity (Hibernate) Business Module Application of the Dependency Inversion Principle (SOLID)
17. 3/21/2025 Copyright © 2025, Oracle and/or its affiliates 17 Fixing the Application / DB Relation DB FlightEntity (Hibernate) Business Module <I> <DTO>
18. 3/21/2025 Copyright © 2025, Oracle and/or its affiliates 18 Refactoring to Data Oriented Programming - About creating sealed types, carrying only state Record FTW! - And adding behavior outside of these types Pattern Matching FTW! Structure of the Lab: Step 2
19. 3/21/2025 Copyright © 2025, Oracle and/or its affiliates 19 Final test: adding a new type, how does it go? Initial situation: you support simple flights Extension: you need to support multileg flights Structure of the Lab: Step 3