code for gRPC

grpc/pom.xml

@@ -0,0 +1,73 @@
+<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>grpc</groupId>
+  <artifactId>grpc-demo</artifactId>
+  <version>0.0.1-SNAPSHOT</version>
+  <packaging>jar</packaging>
+
+  <name>grpc-demo</name>
+  <url>http://maven.apache.org</url>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
+
+  <dependencies>
+	<dependency>
+	    <groupId>io.grpc</groupId>
+	    <artifactId>grpc-netty</artifactId>
+	    <version>1.4.0</version>
+	</dependency>
+	<dependency>
+	    <groupId>io.grpc</groupId>
+	    <artifactId>grpc-protobuf</artifactId>
+	    <version>1.4.0</version>
+	</dependency>
+	<dependency>
+	    <groupId>io.grpc</groupId>
+	    <artifactId>grpc-stub</artifactId>
+	    <version>1.4.0</version>
+	</dependency>
+    <dependency>
+        <groupId>junit</groupId>
+        <artifactId>junit</artifactId>
+        <version>4.12</version>
+        <scope>test</scope>
+    </dependency>
+  </dependencies>
+  <build>   
+  <extensions>
+    <extension>
+      <groupId>kr.motd.maven</groupId>
+      <artifactId>os-maven-plugin</artifactId>
+      <version>1.5.0.Final</version>
+    </extension>
+  </extensions>
+  <plugins>
+    <plugin>
+      <groupId>org.xolstice.maven.plugins</groupId>
+      <artifactId>protobuf-maven-plugin</artifactId>
+      <version>0.5.0</version>
+      <configuration>
+        <protocArtifact>
+          com.google.protobuf:protoc:3.3.0:exe:${os.detected.classifier}
+        </protocArtifact>
+        <pluginId>grpc-java</pluginId>
+        <pluginArtifact>
+          io.grpc:protoc-gen-grpc-java:1.4.0:exe:${os.detected.classifier}
+        </pluginArtifact>
+      </configuration>
+      <executions>
+        <execution>
+          <goals>
+            <goal>compile</goal>
+            <goal>compile-custom</goal>
+          </goals>
+        </execution>
+      </executions>
+    </plugin>
+  </plugins>
+</build>
+</project>

grpc/src/main/java/org/baeldung/grpc/client/GrpcClient.java

@@ -0,0 +1,28 @@
+package org.baeldung.grpc.client;
+
+import org.baeldung.grpc.HelloRequest;
+import org.baeldung.grpc.HelloResponse;
+import org.baeldung.grpc.HelloServiceGrpc;
+
+import io.grpc.ManagedChannel;
+import io.grpc.ManagedChannelBuilder;
+
+public class GrpcClient {
+    public static void main(String[] args) throws InterruptedException {
+        ManagedChannel channel = ManagedChannelBuilder.forAddress("localhost", 8080)
+            .usePlaintext(true)
+            .build();
+
+        HelloServiceGrpc.HelloServiceBlockingStub stub 
+          = HelloServiceGrpc.newBlockingStub(channel);
+
+        HelloResponse helloResponse = stub.hello(HelloRequest.newBuilder()
+            .setFirstName("Baeldung")
+            .setLastName("gRPC")
+            .build());
+
+        System.out.println("Response received from server:\n" + helloResponse);
+
+        channel.shutdown();
+    }
+}

grpc/src/main/java/org/baeldung/grpc/server/GrpcServer.java

@@ -0,0 +1,19 @@
+package org.baeldung.grpc.server;
+
+import java.io.IOException;
+
+import io.grpc.Server;
+import io.grpc.ServerBuilder;
+
+public class GrpcServer
+{
+    public static void main(String[] args) throws IOException, InterruptedException {
+        Server server = ServerBuilder.forPort(8080)
+            .addService(new HelloServiceImpl()).build();
+
+        System.out.println("Starting server...");
+        server.start();
+        System.out.println("Server started!");
+        server.awaitTermination();
+    }
+}

grpc/src/main/java/org/baeldung/grpc/server/HelloServiceImpl.java

@@ -0,0 +1,29 @@
+package org.baeldung.grpc.server;
+
+import org.baeldung.grpc.HelloRequest;
+import org.baeldung.grpc.HelloResponse;
+import org.baeldung.grpc.HelloServiceGrpc.HelloServiceImplBase;
+
+import io.grpc.stub.StreamObserver;
+
+public class HelloServiceImpl extends HelloServiceImplBase {
+
+    @Override
+    public void hello(
+      HelloRequest request, StreamObserver<HelloResponse> responseObserver) {
+        System.out.println("Request received from client:\n" + request);
+
+        String greeting = new StringBuilder().append("Hello, ")
+            .append(request.getFirstName())
+            .append(" ")
+            .append(request.getLastName())
+            .toString();
+
+        HelloResponse response = HelloResponse.newBuilder()
+            .setGreeting(greeting)
+            .build();
+
+        responseObserver.onNext(response);
+        responseObserver.onCompleted();
+    }
+}

grpc/src/main/proto/HelloService.proto

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+syntax = "proto3";
+option java_multiple_files = true;
+package org.baeldung.grpc;
+
+message HelloRequest {
+    string firstName = 1;
+    string lastName = 2;
+}
+
+message HelloResponse {
+    string greeting = 1;
+}
+
+service HelloService {
+    rpc hello(HelloRequest) returns (HelloResponse);
+}