io.reactivex.netty.examples.tcp.echo.EchoServer Maven / Gradle / Ivy
/*
* Copyright 2015 Netflix, Inc.
*
* 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
*
* 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.
*
*/
package io.reactivex.netty.examples.tcp.echo;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandler;
import io.netty.handler.logging.LogLevel;
import io.reactivex.netty.examples.ExamplesEnvironment;
import io.reactivex.netty.protocol.tcp.server.TcpServer;
import org.slf4j.Logger;
import java.nio.charset.Charset;
/**
* A TCP echo server that echoes all input it receives on any connection, after prepending the input with a fixed
* string.
*
* This example just aims to demonstrate how to write the simplest TCP server, it is however, not of much use in general
* primarily because it reads unstructured data i.e. there are no boundaries that define what constitutes "a message".
* In order to define such boundaries, one would typically add a {@link ChannelHandler} that converts the read raw
* {@code ByteBuffer} to a structured message.
*/
public final class EchoServer {
public static void main(final String[] args) {
ExamplesEnvironment env = ExamplesEnvironment.newEnvironment(EchoServer.class);
Logger logger = env.getLogger();
TcpServer server;
/*Starts a new TCP server on an ephemeral port.*/
server = TcpServer.newServer(0)
.enableWireLogging("echo-server", LogLevel.DEBUG)
.start(connection -> connection
.writeStringAndFlushOnEach(connection.getInput()
.map(bb -> bb.toString(Charset.defaultCharset()))
.doOnNext(logger::info)
.map(msg -> "echo => " + msg)));
/*Wait for shutdown if not called from the client (passed an arg)*/
if (env.shouldWaitForShutdown(args)) {
server.awaitShutdown();
}
/*If not waiting for shutdown, assign the ephemeral port used to a field so that it can be read and used by
the caller, if any.*/
env.registerServerAddress(server.getServerAddress());
}
}