[FLINK-23088] Add flink-rpc-core module

flink-rpc/flink-rpc-core/pom.xml

@@ -0,0 +1,50 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you 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
+
+  http://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.
+-->
+<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/maven-v4_0_0.xsd">
+
+	<modelVersion>4.0.0</modelVersion>
+
+	<parent>
+		<groupId>org.apache.flink</groupId>
+		<artifactId>flink-rpc</artifactId>
+		<version>1.14-SNAPSHOT</version>
+		<relativePath>..</relativePath>
+	</parent>
+
+	<artifactId>flink-rpc-core</artifactId>
+	<name>Flink : RPC : Core</name>
+	<packaging>jar</packaging>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.apache.flink</groupId>
+			<artifactId>flink-core</artifactId>
+			<version>${project.version}</version>
+			<scope>provided</scope>
+		</dependency>
+
+		<dependency>
+			<groupId>org.apache.flink</groupId>
+			<artifactId>flink-test-utils-junit</artifactId>
+		</dependency>
+	</dependencies>
+
+</project>

flink-runtime/src/main/java/org/apache/flink/runtime/rpc/RpcEndpoint.java → flink-rpc/flink-rpc-core/src/main/java/org/apache/flink/runtime/rpc/RpcEndpoint.java

@@ -46,7 +46,7 @@
  *
  * <h1>Endpoint and Gateway</h1>
  *
- * To be done...
+ * <p>To be done...
  *
  * <h1>Single Threaded Endpoint Execution </h1>
  *
@@ -76,8 +76,8 @@
  *       not serve RPC requests anymore.
  * </ul>
  *
- * The running state can be queried in a RPC method handler or in the main thread by calling {@link
- * #isRunning()} method.
+ * <p>The running state can be queried in a RPC method handler or in the main thread by calling
+ * {@link #isRunning()} method.
  */
 public abstract class RpcEndpoint implements RpcGateway, AutoCloseableAsync {
 

flink-runtime/src/main/java/org/apache/flink/runtime/rpc/RpcSystem.java → flink-rpc/flink-rpc-core/src/main/java/org/apache/flink/runtime/rpc/RpcSystem.java

@@ -18,10 +18,11 @@
 package org.apache.flink.runtime.rpc;
 
 import org.apache.flink.configuration.Configuration;
-import org.apache.flink.runtime.rpc.akka.AkkaRpcSystem;
 
 import javax.annotation.Nullable;
 
+import java.util.ServiceLoader;
+
 /**
  * This interface serves as a factory interface for RPC services, with some additional utilities
  * that are reliant on implementation details of the RPC service.
@@ -73,7 +74,8 @@ RpcServiceBuilder withExecutorConfiguration(
      * @return loaded RpcSystem
      */
     static RpcSystem load() {
-        return new AkkaRpcSystem();
+        final ClassLoader classLoader = RpcSystem.class.getClassLoader();
+        return ServiceLoader.load(RpcSystem.class, classLoader).iterator().next();
     }
 
     /** Descriptor for creating a fork-join thread-pool. */

flink-runtime/src/main/java/org/apache/flink/runtime/rpc/messages/CallAsync.java → flink-rpc/flink-rpc-core/src/main/java/org/apache/flink/runtime/rpc/messages/CallAsync.java

@@ -22,7 +22,7 @@
 
 import java.util.concurrent.Callable;
 
-/** Message for asynchronous callable invocations */
+/** Message for asynchronous callable invocations. */
 public final class CallAsync {
 
     private final Callable<?> callable;

flink-runtime/src/main/java/org/apache/flink/runtime/rpc/messages/RpcInvocation.java → flink-rpc/flink-rpc-core/src/main/java/org/apache/flink/runtime/rpc/messages/RpcInvocation.java

@@ -38,7 +38,7 @@ public interface RpcInvocation {
     String getMethodName() throws IOException, ClassNotFoundException;
 
     /**
-     * Returns the method's parameter types
+     * Returns the method's parameter types.
      *
      * @return Method's parameter types
      * @throws IOException if the rpc invocation message is a remote message and could not be
@@ -49,7 +49,7 @@ public interface RpcInvocation {
     Class<?>[] getParameterTypes() throws IOException, ClassNotFoundException;
 
     /**
-     * Returns the arguments of the remote procedure call
+     * Returns the arguments of the remote procedure call.
      *
      * @return Arguments of the remote procedure call
      * @throws IOException if the rpc invocation message is a remote message and could not be

flink-runtime/src/main/java/org/apache/flink/runtime/rpc/messages/RunAsync.java → flink-rpc/flink-rpc-core/src/main/java/org/apache/flink/runtime/rpc/messages/RunAsync.java

@@ -21,12 +21,12 @@
 import static org.apache.flink.util.Preconditions.checkArgument;
 import static org.apache.flink.util.Preconditions.checkNotNull;
 
-/** Message for asynchronous runnable invocations */
+/** Message for asynchronous runnable invocations. */
 public final class RunAsync {
 
     private final Runnable runnable;
 
-    /** The delay after which the runnable should be called */
+    /** The delay after which the runnable should be called. */
     private final long atTimeNanos;
 
     /**

flink-rpc/pom.xml

@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you 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
+
+  http://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.
+-->
+<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/maven-v4_0_0.xsd">
+
+	<modelVersion>4.0.0</modelVersion>
+
+	<parent>
+		<groupId>org.apache.flink</groupId>
+		<artifactId>flink-parent</artifactId>
+		<version>1.14-SNAPSHOT</version>
+		<relativePath>..</relativePath>
+	</parent>
+
+	<artifactId>flink-rpc</artifactId>
+	<name>Flink : RPC :</name>
+	<packaging>pom</packaging>
+
+	<modules>
+		<module>flink-rpc-core</module>
+	</modules>
+</project>

flink-runtime/pom.xml

@@ -44,6 +44,12 @@ under the License.
 			<version>${project.version}</version>
 		</dependency>
 
+		<dependency>
+			<groupId>org.apache.flink</groupId>
+			<artifactId>flink-rpc-core</artifactId>
+			<version>${project.version}</version>
+		</dependency>
+
 		<dependency>
 			<groupId>org.apache.flink</groupId>
 			<artifactId>flink-java</artifactId>

flink-runtime/src/main/java/org/apache/flink/runtime/metrics/MetricRegistryConfiguration.java

@@ -71,6 +71,7 @@ public long getQueryServiceMessageSizeLimit() {
      * Create a metric registry configuration object from the given {@link Configuration}.
      *
      * @param configuration to generate the metric registry configuration from
+     * @param maximumFrameSize the maximum message size that the RPC system supports
      * @return Metric registry configuration generated from the configuration
      */
     public static MetricRegistryConfiguration fromConfiguration(

flink-runtime/src/main/resources/META-INF/services/org.apache.flink.runtime.rpc.RpcSystem

@@ -0,0 +1,16 @@
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You 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
+#
+#     http://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.
+
+org.apache.flink.runtime.rpc.akka.AkkaRpcSystem

pom.xml

@@ -55,6 +55,7 @@ under the License.
 		<module>flink-java</module>
 		<module>flink-scala</module>
 		<module>flink-filesystems</module>
+		<module>flink-rpc</module>
 		<module>flink-runtime</module>
 		<module>flink-runtime-web</module>
 		<module>flink-optimizer</module>

tools/ci/stage.sh

@@ -37,6 +37,8 @@ flink-clients,\
 flink-core,\
 flink-java,\
 flink-optimizer,\
+flink-rpc,\
+flink-rpc/flink-rpc-core,\
 flink-runtime,\
 flink-runtime-web,\
 flink-scala,\