Java 26392 Move modules to patterns-module (#15060)

* JAVA-26392 Move axon module and ddd module to patterns-modules * JAVA-26292 Move ddd-contexts to patterns-module
2023-10-27 13:27:32 +03:00
parent 16b931c4df
commit 1028ab97c4
146 changed files with 23 additions and 28 deletions
@@ -0,0 +1,9 @@
+## Domain-driven Design (DDD)
+
+This module contains articles about Domain-driven Design (DDD)
+
+### Relevant articles
+
+- [Persisting DDD Aggregates](https://www.baeldung.com/spring-persisting-ddd-aggregates)
+- [Double Dispatch in DDD](https://www.baeldung.com/ddd-double-dispatch)
+- [Organizing Layers Using Hexagonal Architecture, DDD, and Spring](https://www.baeldung.com/hexagonal-architecture-ddd-spring)
@@ -0,0 +1,99 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>ddd</artifactId>
+    <name>ddd</name>
+    <packaging>jar</packaging>
+    <description>DDD series examples</description>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-boot-2</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-boot-2</relativePath>
+    </parent>
+
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.junit</groupId>
+                <artifactId>junit-bom</artifactId>
+                <version>${junit-jupiter.version}</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+            <dependency>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-dependencies</artifactId>
+                <version>${spring-boot.version}</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-mongodb</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-cassandra</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.joda</groupId>
+            <artifactId>joda-money</artifactId>
+            <version>${joda-money.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-jpa</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.h2database</groupId>
+            <artifactId>h2</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.mysql</groupId>
+            <artifactId>mysql-connector-j</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.postgresql</groupId>
+            <artifactId>postgresql</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-devtools</artifactId>
+            <optional>true</optional>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-validation</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>de.flapdoodle.embed</groupId>
+            <artifactId>de.flapdoodle.embed.mongo</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <joda-money.version>1.0.1</joda-money.version>
+    </properties>
+
+</project>
@@ -0,0 +1,12 @@
+package com.baeldung.ddd;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication(scanBasePackages = "com.baeldung.ddd.order")
+public class PersistingDddAggregatesApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(PersistingDddAggregatesApplication.class, args);
+	}
+}
@@ -0,0 +1,52 @@
+package com.baeldung.ddd.order;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.joda.money.Money;
+
+public class Order {
+    private final List<OrderLine> orderLines;
+    private Money totalCost;
+
+    public Order(List<OrderLine> orderLines) {
+        checkNotNull(orderLines);
+        if (orderLines.isEmpty()) {
+            throw new IllegalArgumentException("Order must have at least one order line item");
+        }
+        this.orderLines = new ArrayList<>(orderLines);
+        totalCost = calculateTotalCost();
+    }
+
+    public void addLineItem(OrderLine orderLine) {
+        checkNotNull(orderLine);
+        orderLines.add(orderLine);
+        totalCost = totalCost.plus(orderLine.cost());
+    }
+
+    public List<OrderLine> getOrderLines() {
+        return new ArrayList<>(orderLines);
+    }
+
+    public void removeLineItem(int line) {
+        OrderLine removedLine = orderLines.remove(line);
+        totalCost = totalCost.minus(removedLine.cost());
+    }
+
+    public Money totalCost() {
+        return totalCost;
+    }
+
+    private Money calculateTotalCost() {
+        return orderLines.stream()
+            .map(OrderLine::cost)
+            .reduce(Money::plus)
+            .get();
+    }
+
+    private static void checkNotNull(Object par) {
+        if (par == null) {
+            throw new NullPointerException("Parameter cannot be null");
+        }
+    }
+}
@@ -0,0 +1,67 @@
+package com.baeldung.ddd.order;
+
+import org.joda.money.Money;
+
+public class OrderLine {
+    private final Product product;
+    private final int quantity;
+
+    public OrderLine(Product product, int quantity) {
+        super();
+        this.product = product;
+        this.quantity = quantity;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        OrderLine other = (OrderLine) obj;
+        if (product == null) {
+            if (other.product != null) {
+                return false;
+            }
+        } else if (!product.equals(other.product)) {
+            return false;
+        }
+        if (quantity != other.quantity) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((product == null) ? 0 : product.hashCode());
+        result = prime * result + quantity;
+        return result;
+    }
+
+    @Override
+    public String toString() {
+        return "OrderLine [product=" + product + ", quantity=" + quantity + "]";
+    }
+
+    Money cost() {
+        return product.getPrice()
+            .multipliedBy(quantity);
+    }
+
+    Product getProduct() {
+        return product;
+    }
+
+    int getQuantity() {
+        return quantity;
+    }
+
+}
@@ -0,0 +1,52 @@
+package com.baeldung.ddd.order;
+
+import org.joda.money.Money;
+
+public class Product {
+    private final Money price;
+
+    public Product(Money price) {
+        super();
+        this.price = price;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        Product other = (Product) obj;
+        if (price == null) {
+            if (other.price != null) {
+                return false;
+            }
+        } else if (!price.equals(other.price)) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((price == null) ? 0 : price.hashCode());
+        return result;
+    }
+
+    @Override
+    public String toString() {
+        return "Product [price=" + price + "]";
+    }
+
+    Money getPrice() {
+        return price;
+    }
+
+}
@@ -0,0 +1,46 @@
+package com.baeldung.ddd.order.config;
+
+import org.bson.Document;
+import org.joda.money.CurrencyUnit;
+import org.joda.money.Money;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.convert.converter.Converter;
+import org.springframework.data.convert.ReadingConverter;
+import org.springframework.data.mongodb.core.convert.MongoCustomConversions;
+
+import java.math.BigDecimal;
+import java.util.Collections;
+
+@Configuration
+public class CustomMongoConfiguration {
+
+    @Bean
+    public MongoCustomConversions customConversions() {
+        return new MongoCustomConversions(Collections.singletonList(DocumentToMoneyConverter.INSTANCE));
+    }
+
+    @ReadingConverter
+    enum DocumentToMoneyConverter implements Converter<Document, Money> {
+
+        INSTANCE;
+
+        @Override
+        public Money convert(Document source) {
+            Document money = source.get("money", Document.class);
+
+            return Money.of(getCurrency(money), getAmount(money));
+        }
+
+        private CurrencyUnit getCurrency(Document money) {
+            Document currency = money.get("currency", Document.class);
+            String currencyCode = currency.getString("code");
+            return CurrencyUnit.of(currencyCode);
+        }
+
+        private BigDecimal getAmount(Document money) {
+            String amount = money.getString("amount");
+            return BigDecimal.valueOf(Double.parseDouble(amount));
+        }
+    }
+}
@@ -0,0 +1,15 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+import org.joda.money.CurrencyUnit;
+import org.joda.money.Money;
+
+public class AmountBasedDiscountPolicy implements DiscountPolicy {
+    @Override
+    public double discount(Order order) {
+        if (order.totalCost()
+            .isGreaterThan(Money.of(CurrencyUnit.USD, 500.00))) {
+            return 0.10;
+        } else
+            return 0;
+    }
+}
@@ -0,0 +1,5 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+public interface DiscountPolicy {
+    double discount(Order order);
+}
@@ -0,0 +1,8 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+public class FlatDiscountPolicy implements DiscountPolicy {
+    @Override
+    public double discount(Order order) {
+        return 0.01;
+    }
+}
@@ -0,0 +1,29 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+import java.math.RoundingMode;
+import java.util.List;
+
+import org.joda.money.Money;
+
+import com.baeldung.ddd.order.OrderLine;
+import com.baeldung.ddd.order.doubledispatch.visitor.OrderVisitor;
+import com.baeldung.ddd.order.doubledispatch.visitor.Visitable;
+
+public class Order extends com.baeldung.ddd.order.Order implements Visitable<OrderVisitor> {
+    public Order(List<OrderLine> orderLines) {
+        super(orderLines);        
+    }
+
+    public Money totalCost(SpecialDiscountPolicy discountPolicy) {
+        return totalCost().multipliedBy(1 - applyDiscountPolicy(discountPolicy), RoundingMode.HALF_UP);
+    }
+
+    protected double applyDiscountPolicy(SpecialDiscountPolicy discountPolicy) {
+        return discountPolicy.discount(this);
+    }
+    
+    @Override
+    public void accept(OrderVisitor visitor) {
+        visitor.visit(this);        
+    }
+}
@@ -0,0 +1,5 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+public interface SpecialDiscountPolicy extends DiscountPolicy {
+    double discount(SpecialOrder order);
+}
@@ -0,0 +1,36 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+import java.util.List;
+
+import com.baeldung.ddd.order.OrderLine;
+import com.baeldung.ddd.order.doubledispatch.visitor.OrderVisitor;
+
+public class SpecialOrder extends Order {
+
+    private boolean eligibleForExtraDiscount;
+
+    public SpecialOrder(List<OrderLine> orderLines) {
+        super(orderLines);
+        this.eligibleForExtraDiscount = false;
+    }
+
+    public SpecialOrder(List<OrderLine> orderLines, boolean eligibleForSpecialDiscount) {
+        super(orderLines);
+        this.eligibleForExtraDiscount = eligibleForSpecialDiscount;
+    }
+
+    public boolean isEligibleForExtraDiscount() {
+        return eligibleForExtraDiscount;
+    }
+
+    @Override
+    protected double applyDiscountPolicy(SpecialDiscountPolicy discountPolicy) {
+        return discountPolicy.discount(this);
+    }
+
+    @Override
+    public void accept(OrderVisitor visitor) {
+        visitor.visit(this);
+    }
+
+}
@@ -0,0 +1,24 @@
+package com.baeldung.ddd.order.doubledispatch.visitor;
+
+import com.baeldung.ddd.order.doubledispatch.Order;
+import com.baeldung.ddd.order.doubledispatch.SpecialOrder;
+
+public class HtmlOrderViewCreator implements OrderVisitor {
+    
+    private String html;
+    
+    public String getHtml() {
+        return html;
+    }
+
+    @Override
+    public void visit(Order order) {
+        html = String.format("<p>Regular order total cost: %s</p>", order.totalCost());
+    }
+
+    @Override
+    public void visit(SpecialOrder order) {
+        html = String.format("<h1>Special Order</h1><p>total cost: %s</p>", order.totalCost());
+    }
+
+}
@@ -0,0 +1,9 @@
+package com.baeldung.ddd.order.doubledispatch.visitor;
+
+import com.baeldung.ddd.order.doubledispatch.Order;
+import com.baeldung.ddd.order.doubledispatch.SpecialOrder;
+
+public interface OrderVisitor {
+    void visit(Order order);
+    void visit(SpecialOrder order);
+}
@@ -0,0 +1,5 @@
+package com.baeldung.ddd.order.doubledispatch.visitor;
+
+public interface Visitable<V> {
+    void accept(V visitor);
+}
@@ -0,0 +1,111 @@
+package com.baeldung.ddd.order.jpa;
+
+import java.math.BigDecimal;
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.persistence.ElementCollection;
+import javax.persistence.Entity;
+import javax.persistence.FetchType;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+import javax.persistence.Table;
+
+@Entity
+@Table(name = "order_table")
+class JpaOrder {
+    private String currencyUnit;
+    @Id
+    @GeneratedValue
+    private Long id;
+    @ElementCollection(fetch = FetchType.EAGER)
+    private final List<JpaOrderLine> orderLines;
+    private BigDecimal totalCost;
+
+    JpaOrder() {
+        totalCost = null;
+        orderLines = new ArrayList<>();
+    }
+
+    JpaOrder(List<JpaOrderLine> orderLines) {
+        checkNotNull(orderLines);
+        if (orderLines.isEmpty()) {
+            throw new IllegalArgumentException("Order must have at least one order line item");
+        }
+        this.orderLines = new ArrayList<>(orderLines);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        JpaOrder other = (JpaOrder) obj;
+        if (id == null) {
+            if (other.id != null) {
+                return false;
+            }
+        } else if (!id.equals(other.id)) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((id == null) ? 0 : id.hashCode());
+        return result;
+    }
+
+    @Override
+    public String toString() {
+        return "JpaOrder [currencyUnit=" + currencyUnit + ", id=" + id + ", orderLines=" + orderLines + ", totalCost=" + totalCost + "]";
+    }
+
+    void addLineItem(JpaOrderLine orderLine) {
+        checkNotNull(orderLine);
+        orderLines.add(orderLine);
+    }
+
+    String getCurrencyUnit() {
+        return currencyUnit;
+    }
+
+    Long getId() {
+        return id;
+    }
+
+    List<JpaOrderLine> getOrderLines() {
+        return new ArrayList<>(orderLines);
+    }
+
+    BigDecimal getTotalCost() {
+        return totalCost;
+    }
+
+    void removeLineItem(int line) {
+        orderLines.remove(line);
+    }
+
+    void setCurrencyUnit(String currencyUnit) {
+        this.currencyUnit = currencyUnit;
+    }
+
+    void setTotalCost(BigDecimal totalCost) {
+        this.totalCost = totalCost;
+    }
+
+    private static void checkNotNull(Object par) {
+        if (par == null) {
+            throw new NullPointerException("Parameter cannot be null");
+        }
+    }
+}
@@ -0,0 +1,70 @@
+package com.baeldung.ddd.order.jpa;
+
+import javax.persistence.Embeddable;
+import javax.persistence.Embedded;
+
+@Embeddable
+class JpaOrderLine {
+    @Embedded
+    private final JpaProduct product;
+    private final int quantity;
+
+    JpaOrderLine() {
+        quantity = 0;
+        product = null;
+    }
+
+    JpaOrderLine(JpaProduct product, int quantity) {
+        super();
+        this.product = product;
+        this.quantity = quantity;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        JpaOrderLine other = (JpaOrderLine) obj;
+        if (product == null) {
+            if (other.product != null) {
+                return false;
+            }
+        } else if (!product.equals(other.product)) {
+            return false;
+        }
+        if (quantity != other.quantity) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((product == null) ? 0 : product.hashCode());
+        result = prime * result + quantity;
+        return result;
+    }
+
+    @Override
+    public String toString() {
+        return "JpaOrderLine [product=" + product + ", quantity=" + quantity + "]";
+    }
+
+    JpaProduct getProduct() {
+        return product;
+    }
+
+    int getQuantity() {
+        return quantity;
+    }
+
+}
@@ -0,0 +1,7 @@
+package com.baeldung.ddd.order.jpa;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface JpaOrderRepository extends JpaRepository<JpaOrder, Long> {
+
+}
@@ -0,0 +1,79 @@
+package com.baeldung.ddd.order.jpa;
+
+import java.math.BigDecimal;
+
+import javax.persistence.Embeddable;
+
+@Embeddable
+class JpaProduct {
+    private String currencyUnit;
+    private BigDecimal price;
+
+    public JpaProduct() {
+    }
+
+    public JpaProduct(BigDecimal price, String currencyUnit) {
+        super();
+        this.price = price;
+        this.currencyUnit = currencyUnit;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        JpaProduct other = (JpaProduct) obj;
+        if (currencyUnit == null) {
+            if (other.currencyUnit != null) {
+                return false;
+            }
+        } else if (!currencyUnit.equals(other.currencyUnit)) {
+            return false;
+        }
+        if (price == null) {
+            if (other.price != null) {
+                return false;
+            }
+        } else if (!price.equals(other.price)) {
+            return false;
+        }
+        return true;
+    }
+
+    public String getCurrencyUnit() {
+        return currencyUnit;
+    }
+
+    public BigDecimal getPrice() {
+        return price;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((currencyUnit == null) ? 0 : currencyUnit.hashCode());
+        result = prime * result + ((price == null) ? 0 : price.hashCode());
+        return result;
+    }
+
+    public void setCurrencyUnit(String currencyUnit) {
+        this.currencyUnit = currencyUnit;
+    }
+
+    public void setPrice(BigDecimal price) {
+        this.price = price;
+    }
+
+    @Override
+    public String toString() {
+        return "JpaProduct [currencyUnit=" + currencyUnit + ", price=" + price + "]";
+    }
+}
@@ -0,0 +1,9 @@
+package com.baeldung.ddd.order.mongo;
+
+import org.springframework.data.mongodb.repository.MongoRepository;
+
+import com.baeldung.ddd.order.Order;
+
+public interface OrderMongoRepository extends MongoRepository<Order, String> {
+
+}
@@ -0,0 +1,37 @@
+package com.baeldung.dddhexagonalspring;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.WebApplicationType;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.annotation.PropertySource;
+
+import com.baeldung.dddhexagonalspring.application.cli.CliOrderController;
+
+@SpringBootApplication
+@PropertySource(value = { "classpath:ddd-layers.properties" })
+public class DomainLayerApplication implements CommandLineRunner {
+
+    public static void main(final String[] args) {
+        SpringApplication application = new SpringApplication(DomainLayerApplication.class);
+        // uncomment to run just the console application
+        // application.setWebApplicationType(WebApplicationType.NONE);
+        application.run(args);
+    }
+
+    @Autowired
+    public CliOrderController orderController;
+
+    @Autowired
+    public ConfigurableApplicationContext context;
+
+    @Override
+    public void run(String... args) throws Exception {
+        orderController.createCompleteOrder();
+        orderController.createIncompleteOrder();
+        // uncomment to stop the context when execution is done
+        // context.close();
+    }
+}
@@ -0,0 +1,47 @@
+package com.baeldung.dddhexagonalspring.application.cli;
+
+import java.math.BigDecimal;
+import java.util.UUID;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+import com.baeldung.dddhexagonalspring.domain.Product;
+import com.baeldung.dddhexagonalspring.domain.service.OrderService;
+
+@Component
+public class CliOrderController {
+
+    private static final Logger LOG = LoggerFactory.getLogger(CliOrderController.class);
+
+    private final OrderService orderService;
+
+    @Autowired
+    public CliOrderController(OrderService orderService) {
+        this.orderService = orderService;
+    }
+
+    public void createCompleteOrder() {
+        LOG.info("<<Create complete order>>");
+        UUID orderId = createOrder();
+        orderService.completeOrder(orderId);
+    }
+
+    public void createIncompleteOrder() {
+        LOG.info("<<Create incomplete order>>");
+        UUID orderId = createOrder();
+    }
+
+    private UUID createOrder() {
+        LOG.info("Placing a new order with two products");
+        Product mobilePhone = new Product(UUID.randomUUID(), BigDecimal.valueOf(200), "mobile");
+        Product razor = new Product(UUID.randomUUID(), BigDecimal.valueOf(50), "razor");
+        LOG.info("Creating order with mobile phone");
+        UUID orderId = orderService.createOrder(mobilePhone);
+        LOG.info("Adding a razor to the order");
+        orderService.addProduct(orderId, razor);
+        return orderId;
+    }
+}
@@ -0,0 +1,20 @@
+package com.baeldung.dddhexagonalspring.application.request;
+
+import com.baeldung.dddhexagonalspring.domain.Product;
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import javax.validation.constraints.NotNull;
+
+public class AddProductRequest {
+    @NotNull private Product product;
+
+    @JsonCreator
+    public AddProductRequest(@JsonProperty("product") final Product product) {
+        this.product = product;
+    }
+
+    public Product getProduct() {
+        return product;
+    }
+}
@@ -0,0 +1,20 @@
+package com.baeldung.dddhexagonalspring.application.request;
+
+import com.baeldung.dddhexagonalspring.domain.Product;
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import javax.validation.constraints.NotNull;
+
+public class CreateOrderRequest {
+    @NotNull private Product product;
+
+    @JsonCreator
+    public CreateOrderRequest(@JsonProperty("product") @NotNull final Product product) {
+        this.product = product;
+    }
+
+    public Product getProduct() {
+        return product;
+    }
+}
@@ -0,0 +1,15 @@
+package com.baeldung.dddhexagonalspring.application.response;
+
+import java.util.UUID;
+
+public class CreateOrderResponse {
+    private final UUID id;
+
+    public CreateOrderResponse(final UUID id) {
+        this.id = id;
+    }
+
+    public UUID getId() {
+        return id;
+    }
+}
@@ -0,0 +1,45 @@
+package com.baeldung.dddhexagonalspring.application.rest;
+
+import com.baeldung.dddhexagonalspring.application.request.AddProductRequest;
+import com.baeldung.dddhexagonalspring.application.request.CreateOrderRequest;
+import com.baeldung.dddhexagonalspring.application.response.CreateOrderResponse;
+import com.baeldung.dddhexagonalspring.domain.service.OrderService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.MediaType;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.UUID;
+
+@RestController
+@RequestMapping("/orders")
+public class OrderController {
+
+    private final OrderService orderService;
+
+    @Autowired
+    public OrderController(OrderService orderService) {
+        this.orderService = orderService;
+    }
+
+    @PostMapping(produces = MediaType.APPLICATION_JSON_VALUE, consumes = MediaType.APPLICATION_JSON_VALUE)
+    CreateOrderResponse createOrder(@RequestBody final CreateOrderRequest createOrderRequest) {
+        final UUID id = orderService.createOrder(createOrderRequest.getProduct());
+
+        return new CreateOrderResponse(id);
+    }
+
+    @PostMapping(value = "/{id}/products", consumes = MediaType.APPLICATION_JSON_VALUE)
+    void addProduct(@PathVariable final UUID id, @RequestBody final AddProductRequest addProductRequest) {
+        orderService.addProduct(id, addProductRequest.getProduct());
+    }
+
+    @DeleteMapping(value = "/{id}/products", consumes = MediaType.APPLICATION_JSON_VALUE)
+    void deleteProduct(@PathVariable final UUID id, @RequestParam final UUID productId) {
+        orderService.deleteProduct(id, productId);
+    }
+
+    @PostMapping("/{id}/complete")
+    void completeOrder(@PathVariable final UUID id) {
+        orderService.completeOrder(id);
+    }
+}
@@ -0,0 +1,7 @@
+package com.baeldung.dddhexagonalspring.domain;
+
+class DomainException extends RuntimeException {
+    DomainException(final String message) {
+        super(message);
+    }
+}
@@ -0,0 +1,96 @@
+package com.baeldung.dddhexagonalspring.domain;
+
+import java.math.BigDecimal;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+import java.util.UUID;
+
+public class Order {
+    private UUID id;
+    private OrderStatus status;
+    private List<OrderItem> orderItems;
+    private BigDecimal price;
+
+    public Order(final UUID id, final Product product) {
+        this.id = id;
+        this.orderItems = new ArrayList<>(Collections.singletonList(new OrderItem(product)));
+        this.status = OrderStatus.CREATED;
+        this.price = product.getPrice();
+    }
+
+    public void complete() {
+        validateState();
+        this.status = OrderStatus.COMPLETED;
+    }
+
+    public void addOrder(final Product product) {
+        validateState();
+        validateProduct(product);
+        orderItems.add(new OrderItem(product));
+        price = price.add(product.getPrice());
+    }
+
+    public void removeOrder(final UUID id) {
+        validateState();
+        final OrderItem orderItem = getOrderItem(id);
+        orderItems.remove(orderItem);
+
+        price = price.subtract(orderItem.getPrice());
+    }
+
+    private OrderItem getOrderItem(final UUID id) {
+        return orderItems.stream()
+            .filter(orderItem -> orderItem.getProductId()
+                .equals(id))
+            .findFirst()
+            .orElseThrow(() -> new DomainException("Product with " + id + " doesn't exist."));
+    }
+
+    private void validateState() {
+        if (OrderStatus.COMPLETED.equals(status)) {
+            throw new DomainException("The order is in completed state.");
+        }
+    }
+
+    private void validateProduct(final Product product) {
+        if (product == null) {
+            throw new DomainException("The product cannot be null.");
+        }
+    }
+
+    public UUID getId() {
+        return id;
+    }
+
+    public OrderStatus getStatus() {
+        return status;
+    }
+
+    public BigDecimal getPrice() {
+        return price;
+    }
+
+    public List<OrderItem> getOrderItems() {
+        return Collections.unmodifiableList(orderItems);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, orderItems, price, status);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (!(obj instanceof Order))
+            return false;
+        Order other = (Order) obj;
+        return Objects.equals(id, other.id) && Objects.equals(orderItems, other.orderItems) && Objects.equals(price, other.price) && status == other.status;
+    }
+
+    private Order() {
+    }
+}
@@ -0,0 +1,39 @@
+package com.baeldung.dddhexagonalspring.domain;
+
+import java.math.BigDecimal;
+import java.util.Objects;
+import java.util.UUID;
+
+public class OrderItem {
+    private UUID productId;
+    private BigDecimal price;
+
+    public OrderItem(final Product product) {
+        this.productId = product.getId();
+        this.price = product.getPrice();
+    }
+
+    public UUID getProductId() {
+        return productId;
+    }
+
+    public BigDecimal getPrice() {
+        return price;
+    }
+
+    private OrderItem() {
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        OrderItem orderItem = (OrderItem) o;
+        return Objects.equals(productId, orderItem.productId) && Objects.equals(price, orderItem.price);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(productId, price);
+    }
+}
--- a/Show More
+++ b/Show More