A Kotlin DSL for finite state machines

A journey through finite state machines and a DSL in Kotlin for implementing your own Finite State Machine.

Transcript

1. A Kotlin DSL for finite state machines Corneil du Plessis Chief Architect, JumpCO
2. About me
3. Quotable quotes K.I.S.S. – Keep it simple stupid! Graeme Mitchell “Everything should be a simple as possible, but no simpler” Albert Einstein
4. What is a state machine?
5. Examples – Packet Reader
6. Examples – Quotation Manager
7. A brief history of state machines • FSM/FSA (Finite state machines / automa) • DFA/NFA/NDFA (Non-deterministic state machine / automa) • State tables / charts / maps • Mealy / Moore machines (State + Input) vs (State) • UML state machines • SDL state machines
8. UML State Diagram
9. Finite State Machines - Turnstile
10. Finite State Machines – Double Lock
11. Finite State Machines – Secure Turnstile
12. State Event Next State Action LOCKED COIN UNLOCKED unlock PASS alarm UNLOCKED COIN return-coin PASS LOCKED lock Transition table for Turnstile
13. FSM Patterns • Generate code from State Map - SMC Class per State, method per Event OR Huge switch statement • Executable XML – SCXML • Language Builder – Spring Statemachine
14. SCXML - Turnstile
15. SMC - Turnstile
16. FSM Features • States • Transition on Events • Guard Expressions • Entry / Exit Actions • Typed Event Parameter • Typed Return value • Automatic transitions • Timeouts • Named State Maps • Push / Pop transitions • Multiplatform • No 3rd party dependencies • Visualisations plugin
17. KFSM DSL for Turnstile
18. Visualisation – Asciidoc – State Map
19. Visualisation – PlantUML – State Diagram
20. Useless Box – State diagram
21. AI Assistive technology for improved UX
22. Typical design pattern for FSM
23. An example – Choose a technology • Kotlin/JS in the Browser Kotlin Only • Kotlin/JS in the Browser JavaScript calling Kotlin • Kotlin JVM in Spring Boot with WebMVC • Kotlin JVM in Spring Boot with REST / HATEOAS (Sample Angular Client) • Kotlin JVM on Android
24. That’s a wrap. Questions?
25. Resources • Twitter - @corneil • Slides - https://speakerdeck.com/corneil/kfsm-a-kotlin-dsl-for- finite-state-machines • Project Source - https://github.com/open-jumpco/kfsm • Samples - https://github.com/open-jumpco/kfsm-samples • SMC - http://smc.sourceforge.net/ • Spring Statemachine - https://projects.spring.io/spring- statemachine/ Questions?