BAEL-7141: Create project structure with API stubs, service provider and service consumer. (#15478)

spring-boot-modules/pom.xml

@@ -91,6 +91,7 @@
         <module>spring-boot-cassandre</module>
         <module>spring-boot-react</module>
         <!-- <module>spring-boot-3</module> --> <!-- JAVA-20931 -->
+        <module>spring-boot-3-grpc</module>
         <module>spring-boot-3-native</module>
         <module>spring-boot-3-observation</module>
         <module>spring-boot-3-test-pitfalls</module>

spring-boot-modules/spring-boot-3-grpc/helloworld-grpc-consumer/pom.xml

@@ -0,0 +1,35 @@
+<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>helloworld-grpc-consumer</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>helloworld-grpc-consumer</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-boot-3</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../../parent-boot-3</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>net.devh</groupId>
+            <artifactId>grpc-client-spring-boot-starter</artifactId>
+            <version>${grpc-spring-boot-starter.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.baeldung.spring-boot-modules</groupId>
+            <artifactId>helloworld-grpc-java</artifactId>
+            <version>1.0.0-SNAPSHOT</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <spring-boot.version>3.2.0</spring-boot.version>
+        <grpc-spring-boot-starter.version>2.15.0.RELEASE</grpc-spring-boot-starter.version>
+    </properties>
+
+</project>

spring-boot-modules/spring-boot-3-grpc/helloworld-grpc-consumer/src/main/java/com/baeldung/helloworld/consumer/HelloWorldClient.java

@@ -0,0 +1,61 @@
+package com.baeldung.helloworld.consumer;
+
+import com.baeldung.helloworld.stubs.HelloWorldRequest;
+import com.baeldung.helloworld.stubs.HelloWorldResponse;
+import com.baeldung.helloworld.stubs.HelloWorldServiceGrpc;
+import io.grpc.stub.StreamObserver;
+import net.devh.boot.grpc.client.inject.GrpcClient;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.context.event.ContextRefreshedEvent;
+import org.springframework.context.event.EventListener;
+import org.springframework.stereotype.Component;
+
+import java.util.stream.Stream;
+
+@Component
+public class HelloWorldClient {
+
+    private static final Logger log = LoggerFactory.getLogger(HelloWorldClient.class);
+
+    // constructor injection not possible
+    // "Do not use in conjunction with @Autowired or @Inject"
+    // (see https://github.com/grpc-ecosystem/grpc-spring)
+    @GrpcClient("hello")
+    HelloWorldServiceGrpc.HelloWorldServiceStub stub;
+
+    @EventListener(ContextRefreshedEvent.class)
+    void sendRequests() {
+        // prepare the response callback
+        final StreamObserver<HelloWorldResponse> responseObserver = new StreamObserver<HelloWorldResponse>() {
+            @Override
+            public void onNext(HelloWorldResponse helloWorldResponse) {
+                log.info("Hello World Response: {}", helloWorldResponse.getGreeting());
+            }
+
+            @Override
+            public void onError(Throwable throwable) {
+                log.error("Error occured", throwable);
+            }
+
+            @Override
+            public void onCompleted() {
+                log.info("Hello World request finished");
+            }
+        };
+        // connect to the server
+        final StreamObserver<HelloWorldRequest> request = stub.sayHello(responseObserver);
+        // send multiple requests (streaming)
+        Stream.of("Tom", "Julia", "Baeldung", "", "Ralf")
+                .map(HelloWorldRequest.newBuilder()::setName)
+                .map(HelloWorldRequest.Builder::build)
+                .forEach(request::onNext);
+        request.onCompleted();
+        try {
+            Thread.sleep(3000);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+}

spring-boot-modules/spring-boot-3-grpc/helloworld-grpc-consumer/src/main/java/com/baeldung/helloworld/consumer/HelloWorldConsumerApplication.java

@@ -0,0 +1,13 @@
+package com.baeldung.helloworld.consumer;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class HelloWorldConsumerApplication {
+
+  public static void main(String[] args) {
+    SpringApplication.run(HelloWorldConsumerApplication.class, args);
+  }
+
+}

spring-boot-modules/spring-boot-3-grpc/helloworld-grpc-consumer/src/main/resources/application.yml

@@ -0,0 +1,11 @@
+grpc:
+  client:
+    hello:
+      address: localhost:9090
+      negotiation-type: plaintext
+logging:
+  pattern:
+    console: "[%d{yyyy-MM-dd HH:mm:ss.SSS}] %-5level [%t] [%logger - %line]: %m%n"
+  level:
+    com.baeldung.helloworld.consumer: info
+  include-application-name: false

spring-boot-modules/spring-boot-3-grpc/helloworld-grpc-java/pom.xml

@@ -0,0 +1,89 @@
+<?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>
+    <parent>
+        <groupId>com.baeldung.spring-boot-modules</groupId>
+        <artifactId>spring-boot-3-grpc</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>helloworld-grpc-java</artifactId>
+
+    <dependencies>
+        <dependency>
+            <groupId>io.grpc</groupId>
+            <artifactId>grpc-protobuf</artifactId>
+            <version>${io.grpc.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>io.grpc</groupId>
+            <artifactId>grpc-stub</artifactId>
+            <version>${io.grpc.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>io.grpc</groupId>
+            <artifactId>grpc-testing</artifactId>
+            <version>${io.grpc.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <!-- we need this because protoc adds a @javax.annotation.Generated annotation to the sources -->
+        <dependency>
+            <groupId>javax.annotation</groupId>
+            <artifactId>javax.annotation-api</artifactId>
+            <version>${annotation-api.version}</version>
+            <scope>provided</scope>
+            <optional>true</optional>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <extensions>
+            <extension>
+                <groupId>kr.motd.maven</groupId>
+                <artifactId>os-maven-plugin</artifactId>
+                <version>${os-maven-plugin.version}</version>
+            </extension>
+        </extensions>
+        <plugins>
+            <plugin>
+                <groupId>org.xolstice.maven.plugins</groupId>
+                <artifactId>protobuf-maven-plugin</artifactId>
+                <version>${protobuf-maven-plugin.version}</version>
+                <configuration>
+                    <protocArtifact>com.google.protobuf:protoc:${protoc.version}:exe:${os.detected.classifier}
+                    </protocArtifact>
+                    <pluginId>grpc-java</pluginId>
+                    <pluginArtifact>io.grpc:protoc-gen-grpc-java:${io.grpc.version}:exe:${os.detected.classifier}
+                    </pluginArtifact>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>protobuf-compile</id>
+                        <goals>
+                            <goal>compile</goal>
+                            <goal>test-compile</goal>
+                        </goals>
+                    </execution>
+                    <execution>
+                        <id>protobuf-compile-custom</id>
+                        <goals>
+                            <goal>compile-custom</goal>
+                            <goal>test-compile-custom</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <io.grpc.version>1.58.0</io.grpc.version>
+        <protoc.version>3.25.1</protoc.version>
+        <os-maven-plugin.version>1.7.1</os-maven-plugin.version>
+        <protobuf-maven-plugin.version>0.6.1</protobuf-maven-plugin.version>
+        <annotation-api.version>1.3.2</annotation-api.version>
+    </properties>
+
+</project>

spring-boot-modules/spring-boot-3-grpc/helloworld-grpc-java/src/main/java/com/baeldung/helloworld/stubs/package-info.java

@@ -0,0 +1,5 @@
+/**
+ * This package contains the gRPC stubs
+ * generated by the protoc compiler.
+ */
+package com.baeldung.helloworld.stubs;

spring-boot-modules/spring-boot-3-grpc/helloworld-grpc-java/src/main/proto/helloworld.proto

@@ -0,0 +1,19 @@
+syntax = "proto3";
+
+option java_package = "com.baeldung.helloworld.stubs";
+option java_multiple_files = true;
+
+message HelloWorldRequest {
+  // a name to greet, default is "World"
+  optional string name = 1;
+}
+
+message HelloWorldResponse {
+  string greeting = 1;
+}
+
+service HelloWorldService {
+
+  rpc SayHello(stream HelloWorldRequest) returns (stream HelloWorldResponse);
+
+}

spring-boot-modules/spring-boot-3-grpc/helloworld-grpc-provider/pom.xml

@@ -0,0 +1,35 @@
+<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>helloworld-grpc-provider</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>helloworld-grpc-provider</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-boot-3</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../../parent-boot-3</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>net.devh</groupId>
+            <artifactId>grpc-server-spring-boot-starter</artifactId>
+            <version>${grpc-spring-boot-starter.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.baeldung.spring-boot-modules</groupId>
+            <artifactId>helloworld-grpc-java</artifactId>
+            <version>1.0.0-SNAPSHOT</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <spring-boot.version>3.2.0</spring-boot.version>
+        <grpc-spring-boot-starter.version>2.15.0.RELEASE</grpc-spring-boot-starter.version>
+    </properties>
+
+</project>

spring-boot-modules/spring-boot-3-grpc/helloworld-grpc-provider/src/main/java/com/baeldung/helloworld/provider/HelloWorldController.java

@@ -0,0 +1,42 @@
+package com.baeldung.helloworld.provider;
+
+import com.baeldung.helloworld.stubs.HelloWorldRequest;
+import com.baeldung.helloworld.stubs.HelloWorldResponse;
+import com.baeldung.helloworld.stubs.HelloWorldServiceGrpc;
+import io.grpc.stub.StreamObserver;
+import net.devh.boot.grpc.server.service.GrpcService;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Optional;
+
+@GrpcService
+public class HelloWorldController extends HelloWorldServiceGrpc.HelloWorldServiceImplBase {
+
+    private static final Logger log = LoggerFactory.getLogger(HelloWorldController.class);
+
+    private HelloWorldResponse sayHello(HelloWorldRequest request) {
+        log.info("Received request: {}", request);
+        return HelloWorldResponse
+                .newBuilder()
+                .setGreeting("Hello "
+                        + Optional
+                        .of(request.getName())
+                        .map(String::trim)
+                        .filter(s -> !s.isEmpty())
+                        .orElse("World")
+                        + "!"
+                )
+                .build();
+    }
+
+    @Override
+    public StreamObserver<HelloWorldRequest> sayHello(
+            StreamObserver<HelloWorldResponse> responseObserver
+    ) {
+        return StreamObserverUtility.proxyStream(
+                responseObserver,
+                this::sayHello
+        );
+    }
+}

spring-boot-modules/spring-boot-3-grpc/helloworld-grpc-provider/src/main/java/com/baeldung/helloworld/provider/HelloWorldProviderApplication.java

@@ -0,0 +1,13 @@
+package com.baeldung.helloworld.provider;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class HelloWorldProviderApplication {
+
+  public static void main(String[] args) {
+    SpringApplication.run(HelloWorldProviderApplication.class, args);
+  }
+
+}

spring-boot-modules/spring-boot-3-grpc/helloworld-grpc-provider/src/main/java/com/baeldung/helloworld/provider/StreamObserverUtility.java

@@ -0,0 +1,35 @@
+package com.baeldung.helloworld.provider;
+
+import io.grpc.stub.StreamObserver;
+
+import java.util.function.Function;
+
+final class StreamObserverUtility {
+
+    private StreamObserverUtility() {
+    }
+
+    static <Target, Source> StreamObserver<Source> proxyStream(
+            StreamObserver<Target> target,
+            Function<Source, Target> handler
+    ) {
+        return new StreamObserver<Source>() {
+            @Override
+            public void onNext(Source value) {
+                final Target targetValue = handler.apply(value);
+                target.onNext(targetValue);
+            }
+
+            @Override
+            public void onError(Throwable t) {
+                target.onError(t);
+            }
+
+            @Override
+            public void onCompleted() {
+                target.onCompleted();
+            }
+        };
+    }
+
+}

spring-boot-modules/spring-boot-3-grpc/helloworld-grpc-provider/src/main/resources/application.yml

@@ -0,0 +1,9 @@
+grpc:
+  server:
+    port: 9090
+logging:
+  pattern:
+    console: "[%d{yyyy-MM-dd HH:mm:ss.SSS}] %-5level [%t] [%logger - %line]: %m%n"
+  level:
+    com.baeldung.helloworld.provider: info
+  include-application-name: false

spring-boot-modules/spring-boot-3-grpc/pom.xml

@@ -0,0 +1,25 @@
+<?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>
+    <groupId>com.baeldung.spring-boot-modules</groupId>
+    <artifactId>spring-boot-3-grpc</artifactId>
+    <version>1.0.0-SNAPSHOT</version>
+    <name>spring-boot-3-grpc</name>
+    <packaging>pom</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../../pom.xml</relativePath>
+    </parent>
+
+    <modules>
+        <module>helloworld-grpc-java</module>
+        <module>helloworld-grpc-provider</module>
+        <module>helloworld-grpc-consumer</module>
+    </modules>
+
+</project>