io.reactivex.netty.examples.tcp.echo.EchoClient 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.handler.logging.LogLevel;
import io.reactivex.netty.examples.ExamplesEnvironment;
import io.reactivex.netty.protocol.tcp.client.TcpClient;
import org.slf4j.Logger;
import rx.Observable;
import java.net.SocketAddress;
import java.nio.charset.Charset;
/**
* A TCP "Hello World" example that sends a string "Hello World!" to the target server and expects an echo response.
*
* There are three ways of running this example:
*
* Default
*
* The default way is to just run this class with no arguments, which will start a server ({@link EchoServer}) on
* an ephemeral port, send a "Hello World!" message to the server and print the response.
*
* After starting {@link EchoServer}
*
* If you want to see how {@link EchoServer} work, you can run {@link EchoServer} by yourself and then pass
* the port on which the server started to this class as a program argument:
*
java io.reactivex.netty.examples.tcp.echo.EchoClient [server port]
*
* Existing TCP server
*
* You can also use this client to connect to an already running TCP server (different than
* {@link EchoServer}) by passing the port and host of the existing server similar to the case above:
*
java io.reactivex.netty.examples.tcp.echo.EchoClient [server port] [server host]
* If the server host is omitted from the above, it defaults to "127.0.0.1"
*
* In all the above usages, this client will print the response received from the server.
*
* @see EchoServer Default server for this client.
*/
public final class EchoClient {
public static void main(String[] args) {
ExamplesEnvironment env = ExamplesEnvironment.newEnvironment(EchoClient.class);
Logger logger = env.getLogger();
/*
* Retrieves the server address, using the following algorithm:
*
- If any arguments are passed, then use the first argument as the server port.
- If available, use the second argument as the server host, else default to localhost
- Otherwise, start the passed server class and use that address.
*/
SocketAddress serverAddress = env.getServerAddress(EchoServer.class, args);
/*Create a new client for the server address*/
TcpClient.newClient(serverAddress)
.enableWireLogging("echo-client", LogLevel.DEBUG)
.createConnectionRequest()
.flatMap(connection ->
connection.writeString(Observable.just("Hello World!"))
.cast(ByteBuf.class)
.concatWith(connection.getInput())
)
.take(1)
.map(bb -> bb.toString(Charset.defaultCharset()))
.toBlocking()
.forEach(logger::info);
}
}