GH-742 Add initial support for gRPC

Resolves #742

spring-cloud-function-grpc/src/main/java/org/springframework/cloud/function/grpc/FunctionGrpcProperties.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2021-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.function.grpc;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.cloud.function.context.FunctionProperties;
+
+/**
+ *
+ * @author Oleg Zhurakousky
+ * @since 3.2
+ *
+ */
+@ConfigurationProperties(prefix = FunctionProperties.PREFIX + ".grpc")
+public class FunctionGrpcProperties {
+
+	/**
+	 * Default gRPC port.
+	 */
+	public final static int GRPC_PORT = 55555;
+
+	private int port = GRPC_PORT;
+
+	/**
+	 * Grpc Server port.
+	 */
+	public int getPort() {
+		return this.port;
+	}
+
+	public void setPort(int port) {
+		this.port = port;
+	}
+}

spring-cloud-function-grpc/src/main/java/org/springframework/cloud/function/grpc/GrpcAutoConfiguration.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2021-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.function.grpc;
+
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.cloud.function.context.FunctionCatalog;
+import org.springframework.cloud.function.context.FunctionProperties;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ *
+ * @author Oleg Zhurakousky
+ * @since 3.2
+ */
+@Configuration(proxyBeanMethods = false)
+@EnableConfigurationProperties(FunctionGrpcProperties.class)
+public class GrpcAutoConfiguration {
+
+	@Bean
+	@ConditionalOnProperty(name = "spring.cloud.function.grpc.mode", havingValue = "server", matchIfMissing = false)
+	public GrpcServer grpcServer(FunctionGrpcProperties grpcProperties, GrpcMessagingServiceImpl grpcMessagingService) {
+		return new GrpcServer(grpcProperties, grpcMessagingService);
+	}
+
+
+	@Bean
+	public GrpcMessagingServiceImpl grpcMessageService(FunctionProperties funcProperties, FunctionCatalog functionCatalog) {
+		return new GrpcMessagingServiceImpl(funcProperties, functionCatalog);
+	}
+}

spring-cloud-function-grpc/src/main/java/org/springframework/cloud/function/grpc/GrpcMessagingServiceImpl.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2021-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * Copyright 2021-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.function.grpc;
+
+import io.grpc.stub.StreamObserver;
+
+import org.springframework.cloud.function.context.FunctionCatalog;
+import org.springframework.cloud.function.context.FunctionProperties;
+import org.springframework.cloud.function.context.catalog.SimpleFunctionRegistry.FunctionInvocationWrapper;
+import org.springframework.cloud.function.grpc.MessagingServiceGrpc.MessagingServiceImplBase;
+import org.springframework.messaging.Message;
+
+class GrpcMessagingServiceImpl extends MessagingServiceImplBase {
+
+	private final FunctionInvocationWrapper function;
+
+	GrpcMessagingServiceImpl(FunctionProperties funcProperties, FunctionCatalog functionCatalog) {
+		this.function = functionCatalog.lookup(funcProperties.getDefinition(), "application/json");
+	}
+
+
+	@Override
+	public void requestReply(GrpcMessage request, StreamObserver<GrpcMessage> responseObserver) {
+		Message<byte[]> message = GrpcUtils.fromGrpcMessage(request);
+		Message<byte[]> replyMessage = (Message<byte[]>) this.function.apply(message);
+
+		GrpcMessage reply = GrpcUtils.toGrpcMessage(replyMessage);
+		/*
+		 * The above is effectively echo. This is where we plug in function invocation
+		 */
+		responseObserver.onNext(reply);
+		responseObserver.onCompleted();
+	}
+//
+//	@Override
+//	public void serverStream(GrpcMessage request,
+//			StreamObserver<GrpcMessage> responseObserver) {
+//
+//	}
+//
+//	@Override
+//	public StreamObserver<GrpcMessage> clientStream(
+//			StreamObserver<GrpcMessage> responseObserver) {
+//		return null;
+//	}
+//
+//	@Override
+//	public StreamObserver<GrpcMessage> biStream(
+//			StreamObserver<GrpcMessage> responseObserver) {
+//		return null;
+//	}
+}

spring-cloud-function-grpc/src/main/java/org/springframework/cloud/function/grpc/GrpcServer.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2021-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.function.grpc;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+import io.grpc.Server;
+import io.grpc.ServerBuilder;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import org.springframework.cloud.function.grpc.MessagingServiceGrpc.MessagingServiceImplBase;
+import org.springframework.context.SmartLifecycle;
+
+class GrpcServer implements SmartLifecycle {
+
+	protected Log logger = LogFactory.getLog(GrpcServer.class);
+
+	private final FunctionGrpcProperties grpcProperties;
+
+	private final MessagingServiceImplBase grpcMessageService;
+
+	private final ExecutorService executor = Executors.newSingleThreadExecutor();
+
+	private Server server;
+
+	GrpcServer(FunctionGrpcProperties grpcProperties, MessagingServiceImplBase grpcMessageService) {
+		this.grpcProperties = grpcProperties;
+		this.grpcMessageService = grpcMessageService;
+	}
+
+	@Override
+	public void start() {
+		this.executor.execute(() -> {
+			try {
+				this.server = ServerBuilder.forPort(this.grpcProperties.getPort())
+						.addService(this.grpcMessageService)
+						.build();
+
+				logger.info("Starting gRPC server");
+				this.server.start();
+				logger.info("gRPC server is listening on port " + this.grpcProperties.getPort());
+			}
+			catch (Exception e) {
+				throw new IllegalStateException(e);
+			}
+		});
+	}
+
+	@Override
+	public void stop() {
+		logger.info("Shutting down gRPC server");
+		this.server.shutdown();
+		this.executor.shutdown();
+	}
+
+	@Override
+	public boolean isRunning() {
+		return this.server != null && !this.server.isShutdown();
+	}
+}

spring-cloud-function-grpc/src/main/java/org/springframework/cloud/function/grpc/GrpcUtils.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2021-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.function.grpc;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import com.google.protobuf.ByteString;
+import io.grpc.ManagedChannel;
+import io.grpc.ManagedChannelBuilder;
+
+import org.springframework.messaging.Message;
+import org.springframework.messaging.support.MessageBuilder;
+
+/**
+ *
+ * @author Oleg Zhurakousky
+ * @since 3.2
+ *
+ */
+public final class GrpcUtils {
+
+	private GrpcUtils() {
+
+	}
+
+	public static GrpcMessage toGrpcMessage(byte[] payload, Map<String, String> headers) {
+		return GrpcMessage.newBuilder()
+				.setPayload(ByteString.copyFrom(payload))
+				.putAllHeaders(headers)
+				.build();
+	}
+
+	public static GrpcMessage toGrpcMessage(Message<byte[]> message) {
+		Map<String, String> stringHeaders = new HashMap<>();
+		message.getHeaders().forEach((k, v) -> {
+			stringHeaders.put(k, v.toString());
+		});
+		return toGrpcMessage(message.getPayload(), stringHeaders);
+	}
+
+	public static Message<byte[]> fromGrpcMessage(GrpcMessage message) {
+		return MessageBuilder.withPayload(message.getPayload().toByteArray())
+				.copyHeaders(message.getHeadersMap())
+				.build();
+	}
+
+	public static Message<byte[]> requestReply(Message<byte[]> inputMessage) {
+		return requestReply("localhost", FunctionGrpcProperties.GRPC_PORT, inputMessage);
+	}
+
+	public static Message<byte[]> requestReply(String host, int port, Message<byte[]> inputMessage) {
+		ManagedChannel channel = ManagedChannelBuilder.forAddress("localhost", 55555)
+				.usePlaintext().build();
+		MessagingServiceGrpc.MessagingServiceBlockingStub stub = MessagingServiceGrpc
+				.newBlockingStub(channel);
+
+		GrpcMessage response = stub.requestReply(toGrpcMessage(inputMessage));
+		channel.shutdown();
+		return fromGrpcMessage(response);
+	}
+}

spring-cloud-function-grpc/src/main/proto/MessageService.proto

@@ -0,0 +1,18 @@
+syntax = "proto3";
+option java_multiple_files = true;
+package org.springframework.cloud.function.grpc;
+
+message GrpcMessage {
+    bytes payload = 1;
+    map<string, string> headers = 2;
+}
+
+service MessagingService {
+    rpc biStream(stream GrpcMessage) returns (stream GrpcMessage);
+    
+    rpc clientStream(stream GrpcMessage) returns (GrpcMessage);
+    
+    rpc serverStream(GrpcMessage) returns (stream GrpcMessage);
+    
+    rpc requestReply(GrpcMessage) returns (GrpcMessage);
+}

spring-cloud-function-grpc/src/main/resources/META-INF/spring.factories

@@ -0,0 +1,2 @@
+org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
+org.springframework.cloud.function.grpc.GrpcAutoConfiguration

spring-cloud-function-grpc/src/test/java/org/springframework/cloud/function/grpc/GrpcInteractionTests.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2021-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.function.grpc;
+
+
+
+import java.util.function.Function;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.WebApplicationType;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.MessageHeaders;
+import org.springframework.messaging.support.MessageBuilder;
+import org.springframework.util.MimeTypeUtils;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class GrpcInteractionTests {
+
+	@Test
+	public void test() {
+		try (ConfigurableApplicationContext context = new SpringApplicationBuilder(
+				SampleConfiguration.class).web(WebApplicationType.NONE).run(
+						"--spring.jmx.enabled=false",
+						"--spring.cloud.function.definition=uppercase",
+						"--spring.cloud.function.grpc.port=55555",
+						"--spring.cloud.function.grpc.mode=server")) {
+
+			Message<byte[]> message = MessageBuilder.withPayload("hello gRPC".getBytes())
+					.setHeader("foo", "bar")
+					.setHeader(MessageHeaders.CONTENT_TYPE, MimeTypeUtils.TEXT_PLAIN)
+					.build();
+
+			Message<byte[]> reply = GrpcUtils.requestReply(message);
+
+			assertThat(reply.getPayload()).isEqualTo("\"HELLO GRPC\"".getBytes());
+		}
+	}
+
+	@EnableAutoConfiguration
+	public static class SampleConfiguration {
+
+		@Bean
+		public Function<String, String> uppercase() {
+			return v -> v.toUpperCase();
+		}
+	}
+}

spring-cloud-function-grpc/src/test/resources/application.properties

@@ -0,0 +1 @@
+