bgoetzmann

Intro

Kotlin is a new programming language for the JVM. It produces Java bytecode, supports Android and generates JavaScript. The latest version of the language is Kotlin M5.3

Kotlin project website is at kotlin.jetbrains.org.

All the codes here can be copied and run on Kotlin online editor.

Let's get started.

bgoetzmann

// See "A Guide to the Axon Framework", https://www.baeldung.com/axon-cqrs-event-sourcing

@Grab('org.axonframework:axon-core:3.3.2')
import org.axonframework.commandhandling.AggregateAnnotationCommandHandler
import org.axonframework.commandhandling.TargetAggregateIdentifier
import org.axonframework.commandhandling.model.AggregateIdentifier
import org.axonframework.commandhandling.CommandHandler
import org.axonframework.eventhandling.EventHandler
import org.axonframework.commandhandling.SimpleCommandBus
import org.axonframework.commandhandling.gateway.DefaultCommandGateway

bgoetzmann

def _makeAddItemCommand(Item item) {
    { Cart cart -> cart.addItem(item) }
}

def _makeRemoveItemCommand(Item item) {
    { Cart cart -> cart.removeItem(item) }
}

def actions = [
    _makeAddItemCommand(new Item(name: 'Item1', price: 1)),

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def fpCart = new Cart()

// Create command
def addItem1 = makeAddItemCommand(fpCart, new Item(name: 'Item1', price: 1))

// Invoke command
addItem1()

assert fpCart.items.keySet() == ['Item1'] as Set

bgoetzmann

def makeAddItemCommand(Cart cart, Item item) {
    { -> cart.addItem(item) }
}

def makeRemoveItemCommand(Cart cart, Item item) {
    { -> cart.removeItem(item) }
}

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class MacroCartCommand implements CartCommand {
    def commands = []
    
    MacroCartCommand leftShift(CartCommand command) {
        commands << command
        this
    }

    void setReceiver(Cart cart) {
        commands*.cart = cart

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class Item {
    String name
    Double price
}

class Cart {
    Map items = [:]

    Cart addItem(Item item) {
        items[item.name] = item

bgoetzmann

@RegisterRestClient  
@Produces(MediaType.APPLICATION_JSON)
public interface SwapiService {  
    @GET  
    @Path("/people/{id}")  
    JsonObject getCharacter(@PathParam("id") String id);  
  
    @GET  
    @Path("/people")  
    JsonObject getPeople();  

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@Inject  
@RestClient  
private SwapiService swapiService;

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JsonObject character = swapiService.getCharacter("1");
String name = character.getString("name");