Spring,Dropwizard: Currency Exchange impl

Author: bitxon

README.md

@@ -4,6 +4,6 @@
 
 ## Quick start
 1. Build: `./gradlew clean build`
-2. Spin Up DB: `docker-compose -f docker-compose.yml up -d`
+2. Spin Up DB And Wiremock: `docker-compose -f docker-compose.yml up -d`
 3. Start one App: `./run-dropwizard.sh` or `./run-spring.sh`
 4. Run Gatling: `./gradlew :loadtest:gatlingRun`

common-api/src/main/java/bitxon/api/thirdparty/exchange/model/ExchangeRate.java

@@ -0,0 +1,18 @@
+package bitxon.api.thirdparty.exchange.model;
+
+import java.util.Map;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+public class ExchangeRate {
+
+    private String base;
+    private Map<String, Double> rates;
+}

common-wiremock/build.gradle

@@ -0,0 +1,7 @@
+plugins {
+    id 'java'
+}
+
+group = 'bitxon'
+version = '1.0-SNAPSHOT'
+sourceCompatibility = '17'

common-wiremock/src/main/resources/stubs/__files/base-eur-response.json

@@ -0,0 +1,7 @@
+{
+  "base": "EUR",
+  "rates": {
+    "USD": 1.0,
+    "GBP": 0.5
+  }
+}

common-wiremock/src/main/resources/stubs/__files/base-gbp-response.json

@@ -0,0 +1,7 @@
+{
+  "base": "GBP",
+  "rates": {
+    "USD": 2.0,
+    "EUR": 2.0
+  }
+}

common-wiremock/src/main/resources/stubs/__files/base-usd-response.json

@@ -0,0 +1,7 @@
+{
+  "base": "USD",
+  "rates": {
+    "EUR": 1.0,
+    "GBP": 0.5
+  }
+}

common-wiremock/src/main/resources/stubs/mappings/get-eur-200.json

@@ -0,0 +1,13 @@
+{
+  "request": {
+    "url": "/exchanges?currency=EUR",
+    "method": "GET"
+  },
+  "response": {
+    "status": 200,
+    "bodyFileName": "base-eur-response.json",
+    "headers": {
+      "Content-Type": "application/json; charset=UTF-8"
+    }
+  }
+}

common-wiremock/src/main/resources/stubs/mappings/get-gbp-200.json

@@ -0,0 +1,13 @@
+{
+  "request": {
+    "url": "/exchanges?currency=GBP",
+    "method": "GET"
+  },
+  "response": {
+    "status": 200,
+    "bodyFileName": "base-gbp-response.json",
+    "headers": {
+      "Content-Type": "application/json; charset=UTF-8"
+    }
+  }
+}

common-wiremock/src/main/resources/stubs/mappings/get-usd-200.json

@@ -0,0 +1,13 @@
+{
+  "request": {
+    "url": "/exchanges?currency=USD",
+    "method": "GET"
+  },
+  "response": {
+    "status": 200,
+    "bodyFileName": "base-usd-response.json",
+    "headers": {
+      "Content-Type": "application/json; charset=UTF-8"
+    }
+  }
+}

docker-compose.yml

@@ -8,4 +8,13 @@ services:
       - POSTGRES_USER=postgres
       - POSTGRES_PASSWORD=postgres
     ports:
-      - '5432:5432'
+      - '5432:5432'
+
+  wiremock:
+    image: wiremock/wiremock:2.32.0
+    ports:
+      - "8888:8080"
+    command:
+      - "--global-response-templating"
+    volumes:
+      - ./common-wiremock/src/main/resources/stubs:/home/wiremock

dropwizard-app/build.gradle

@@ -26,6 +26,8 @@ dependencies {
     runtimeOnly 'org.postgresql:postgresql:42.4.0'
 
     testImplementation 'io.dropwizard:dropwizard-testing:2.1.1'
+    testImplementation project(":common-wiremock")
+    testImplementation 'com.github.tomakehurst:wiremock:2.27.2'
     testImplementation 'org.testcontainers:testcontainers:1.17.3'
     testImplementation 'org.testcontainers:junit-jupiter:1.17.3'
     testImplementation 'org.testcontainers:postgresql:1.17.3'

dropwizard-app/src/main/java/bitxon/dropwizard/DropwizardApplication.java

@@ -1,12 +1,14 @@
 package bitxon.dropwizard;
 
+import bitxon.dropwizard.client.exchange.ExchangeClient;
 import bitxon.dropwizard.customization.ClasspathOrFileConfigurationSourceProvider;
 import bitxon.dropwizard.db.AccountDao;
 import bitxon.dropwizard.db.AccountDaoHibernateImpl;
 import bitxon.dropwizard.db.model.Account;
 import bitxon.dropwizard.mapper.AccountMapper;
 import bitxon.dropwizard.resource.AccountResource;
 import io.dropwizard.Application;
+import io.dropwizard.client.JerseyClientBuilder;
 import io.dropwizard.db.DataSourceFactory;
 import io.dropwizard.db.PooledDataSourceFactory;
 import io.dropwizard.hibernate.dual.HibernateBundle;
@@ -50,6 +52,14 @@ protected void configure() {
             }
         });
 
+
+        var client = new JerseyClientBuilder(environment)
+            .using(configuration.getExchangeClientConfig())
+            .build("exchangeClient");
+        var exchangeClient = new ExchangeClient(client, configuration.getExchangeClientConfig());
+        environment.jersey().register(exchangeClient);
+
+
         environment.jersey().register(AccountResource.class);
     }
 

dropwizard-app/src/main/java/bitxon/dropwizard/DropwizardConfiguration.java

@@ -1,9 +1,12 @@
 package bitxon.dropwizard;
 
 import javax.validation.Valid;
+import javax.validation.constraints.NotBlank;
 import javax.validation.constraints.NotNull;
 
+import com.fasterxml.jackson.annotation.JsonProperty;
 import io.dropwizard.Configuration;
+import io.dropwizard.client.JerseyClientConfiguration;
 import io.dropwizard.db.DataSourceFactory;
 import lombok.Data;
 import lombok.EqualsAndHashCode;
@@ -15,4 +18,19 @@ public class DropwizardConfiguration extends Configuration {
     @Valid
     @NotNull
     private DataSourceFactory database = new DataSourceFactory();
+
+    @Valid
+    @NotNull
+    private DropwizardConfiguration.ExchangeClientConfig exchangeClientConfig = new ExchangeClientConfig();
+
+
+    @Data
+    @EqualsAndHashCode(callSuper = false)
+    public static class ExchangeClientConfig extends JerseyClientConfiguration {
+
+        @NotBlank
+        @JsonProperty("basePath")
+        String basePath;
+
+    }
 }

dropwizard-app/src/main/java/bitxon/dropwizard/client/exchange/ExchangeClient.java

@@ -0,0 +1,21 @@
+package bitxon.dropwizard.client.exchange;
+
+import javax.ws.rs.client.Client;
+
+import bitxon.api.thirdparty.exchange.model.ExchangeRate;
+import bitxon.dropwizard.DropwizardConfiguration;
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+public class ExchangeClient {
+
+    private final Client client;
+    private final DropwizardConfiguration.ExchangeClientConfig config;
+
+    public ExchangeRate getExchangeRate(String currency) {
+        var response = client.target(config.getBasePath() + currency)
+            .request()
+            .get(ExchangeRate.class);
+        return response;
+    }
+}

dropwizard-app/src/main/java/bitxon/dropwizard/resource/AccountResource.java

@@ -20,6 +20,7 @@
 
 import bitxon.api.model.Account;
 import bitxon.api.model.MoneyTransfer;
+import bitxon.dropwizard.client.exchange.ExchangeClient;
 import bitxon.dropwizard.db.AccountDao;
 import bitxon.dropwizard.mapper.AccountMapper;
 import io.dropwizard.hibernate.UnitOfWork;
@@ -33,6 +34,7 @@ public class AccountResource {
 
     private final AccountDao dao;
     private final AccountMapper mapper;
+    private final ExchangeClient exchangeClient;
 
     @GET
     @UnitOfWork
@@ -73,14 +75,17 @@ public void transfer(@NotNull @Valid MoneyTransfer transfer,
         var recipient = dao.findById(transfer.getRecipientId())
             .orElseThrow(() -> new RuntimeException("Recipient not found"));
 
+        var exchangeRateValue = exchangeClient.getExchangeRate(sender.getCurrency())
+            .getRates().getOrDefault(recipient.getCurrency(), 1.0);
+
         sender.setMoneyAmount(sender.getMoneyAmount() - transfer.getMoneyAmount());
         dao.save(sender);
 
         if (FAIL_TRANSFER.equals(dirtyTrick)) {
             throw new RuntimeException("Error during money transfer");
         }
 
-        recipient.setMoneyAmount(recipient.getMoneyAmount() + transfer.getMoneyAmount());
+        recipient.setMoneyAmount(recipient.getMoneyAmount() + (int)(transfer.getMoneyAmount() * exchangeRateValue));
         dao.save(recipient);
     }
 }

dropwizard-app/src/main/resources/config.yml

@@ -17,6 +17,9 @@ database:
     #hibernate.show_sql: true
     #hibernate.hbm2ddl.import_files:
 
+exchangeClientConfig:
+  basePath: 'http://localhost:8888/exchanges?currency='
+
 logging:
   level: INFO
   loggers:

dropwizard-app/src/test/java/bitxon/dropwizard/AbstractDropwizardTest.java

@@ -6,6 +6,9 @@
 import javax.ws.rs.client.Client;
 
 
+import com.github.tomakehurst.wiremock.WireMockServer;
+import com.github.tomakehurst.wiremock.client.WireMock;
+import com.github.tomakehurst.wiremock.core.WireMockConfiguration;
 import io.dropwizard.client.JerseyClientBuilder;
 import io.dropwizard.testing.DropwizardTestSupport;
 import io.dropwizard.testing.ResourceHelpers;
@@ -16,6 +19,7 @@
 public abstract class AbstractDropwizardTest {
 
     private static final PostgreSQLContainer DB;
+    public static final WireMockServer WIREMOCK;
     private static final DropwizardTestSupport<DropwizardConfiguration> APP;
     private static final Client CLIENT;
 
@@ -27,12 +31,20 @@ public abstract class AbstractDropwizardTest {
             .withInitScript("sql/db-test-data.sql");
         DB.start();
 
+        WIREMOCK = new WireMockServer(WireMockConfiguration.options()
+            .usingFilesUnderClasspath("stubs") // Loading stubs from common-wiremock
+            .dynamicPort()
+        );
+        WIREMOCK.start();
+        WireMock.configureFor(WIREMOCK.port());
+
         APP = new DropwizardTestSupport<>(DropwizardApplication.class,
             ResourceHelpers.resourceFilePath("config-test.yml"),
             //config("server.applicationConnectors[0].port", "0"),
             config("database.url", DB.getJdbcUrl()),
             config("database.user", DB.getUsername()),
-            config("database.password", DB.getPassword())
+            config("database.password", DB.getPassword()),
+            config("exchangeClientConfig.basePath", WIREMOCK.baseUrl() + "/exchanges?currency=")
         );
         try {
             // This trick helps to spin up application once

dropwizard-app/src/test/java/bitxon/dropwizard/MoneyTransferDropwizardTest.java

@@ -42,6 +42,37 @@ void transfer() throws Exception {
         assertThat(retrieveUserMoneyAmount(recipientId)).isEqualTo(recipientMoneyAmountResult);
     }
 
+    @Test
+    void transferFromGBPToUSD() throws Exception {
+        var transferAmount = 40;
+        var exchangeRate = 2.0d;
+        // Sender
+        var senderId = 6L;
+        var senderMoneyAmountOriginal = 80; // GPB
+        var senderMoneyAmountResult = senderMoneyAmountOriginal - transferAmount;
+        // Recipient
+        var recipientId = 5L;
+        var recipientMoneyAmountOriginal = 100; // USD
+        var recipientMoneyAmountResult = recipientMoneyAmountOriginal + (int)(transferAmount * exchangeRate);
+
+        var requestBody = MoneyTransfer.builder()
+            .senderId(senderId)
+            .recipientId(recipientId)
+            .moneyAmount(transferAmount)
+            .build();
+
+        var response = client()
+            .target(String.format("http://localhost:%d/accounts/transfers", appLocalPort()))
+            .request()
+            .buildPost(Entity.entity(requestBody, "application/json"))
+            .submit()
+            .get();
+
+        assertThat(response.getStatus()).isEqualTo(204);
+        assertThat(retrieveUserMoneyAmount(senderId)).isEqualTo(senderMoneyAmountResult);
+        assertThat(retrieveUserMoneyAmount(recipientId)).isEqualTo(recipientMoneyAmountResult);
+    }
+
     @Test
     void transferWithServerProblemDuringTransfer() throws Exception {
         var transferAmount = 40;

dropwizard-app/src/test/resources/config-test.yml

@@ -17,6 +17,9 @@ database:
     #hibernate.show_sql: true
     #hibernate.hbm2ddl.import_files:
 
+exchangeClientConfig:
+  basePath: 'will-be-replaced-in-test'
+
 logging:
   level: INFO
   loggers:

dropwizard-app/src/test/resources/sql/db-test-data.sql

@@ -11,4 +11,5 @@ INSERT INTO account (id, email, currency, money_amount) VALUES
     (DEFAULT, '[email protected]', 'USD', 573),
     (DEFAULT, '[email protected]', 'USD', 79),
     (DEFAULT, '[email protected]', 'USD', 33),
-    (DEFAULT, '[email protected]', 'USD', 100);
+    (DEFAULT, '[email protected]', 'USD', 100),
+    (DEFAULT, '[email protected]', 'GBP', 80);

settings.gradle

@@ -1,5 +1,6 @@
 rootProject.name = 'java-microservices'
 include 'common-api'
+include 'common-wiremock'
 include 'spring-app'
 include 'dropwizard-app'
 include 'loadtest'

spring-app/build.gradle

@@ -26,6 +26,8 @@ dependencies {
     runtimeOnly 'org.postgresql:postgresql:42.4.0'
 
     testImplementation 'org.springframework.boot:spring-boot-starter-test'
+    testImplementation project(":common-wiremock")
+    testImplementation 'org.springframework.cloud:spring-cloud-contract-wiremock:3.1.3'
     testImplementation 'org.testcontainers:testcontainers:1.17.3'
     testImplementation 'org.testcontainers:junit-jupiter:1.17.3'
     testImplementation 'org.testcontainers:postgresql:1.17.3'

spring-app/src/main/java/bitxon/spring/client/ExchangeClient.java

@@ -0,0 +1,23 @@
+package bitxon.spring.client;
+
+import bitxon.api.thirdparty.exchange.model.ExchangeRate;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Component;
+import org.springframework.web.client.RestTemplate;
+
+@Component
+@RequiredArgsConstructor
+public class ExchangeClient {
+
+    private final RestTemplate restTemplate;
+    private final ExchangeClientProperties exchangeClientProperties;
+
+
+    public ExchangeRate getExchangeRate(String currency) {
+        var response = restTemplate.getForObject(
+            exchangeClientProperties.getBasePath() + currency,
+            ExchangeRate.class
+        );
+        return response;
+    }
+}