io.reactivex.netty.examples.http.ws.messaging.MessagingClient 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.http.ws.messaging;
import io.netty.handler.codec.http.websocketx.BinaryWebSocketFrame;
import io.netty.handler.codec.http.websocketx.WebSocketFrame;
import io.netty.handler.logging.LogLevel;
import io.reactivex.netty.examples.ExamplesEnvironment;
import io.reactivex.netty.protocol.http.client.HttpClient;
import io.reactivex.netty.protocol.http.ws.client.WebSocketResponse;
import org.slf4j.Logger;
import rx.Observable;
import java.io.IOException;
import java.net.SocketAddress;
import java.util.concurrent.TimeUnit;
/**
* An example to demonstrate how to use WebSocket to send messages to a messaging server.
* This example sends a stream of 10 {@link MessageFrame} to the specified server and expects 10 acknowledgments in
* 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 MessagingServer})
* on an ephemeral port and then send an HTTP request to that server and print the response.
*
* After starting {@link MessagingServer}
*
* If you want to see how {@link MessagingServer} work, you can run {@link MessagingServer} by yourself and
* then pass the port on which the server started to this class as a program argument:
*
java io.reactivex.netty.examples.http.ws.messaging.MessagingClient [server port]
*
* Existing HTTP server
*
* You can also use this client to send a GET request "/ws" to an existing HTTP server (different than
* {@link MessagingServer}) by passing the port and host of the existing server similar to the case above:
*
java io.reactivex.netty.examples.http.ws.messaging.MessagingClient [server port]
* 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.
*
* Retry
*
* If the client does not receive acknowledgments for any message ID for 10 seconds, it re-sends the message. See
* {@link PendingMessageTracker} for the relevant code.
* This means that this example follows the atleast once delivery semantics.
*
* Message buffering
*
* Since, message production is asynchronous, if this client can not connect to the server, it will buffer the messages
* in memory and wait for the server to come up.
*/
public final class MessagingClient {
public static void main(String[] args) {
ExamplesEnvironment env = ExamplesEnvironment.newEnvironment(MessagingClient.class);
/*
* 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 socketAddress = env.getServerAddress(MessagingServer.class, args);
Logger logger = env.getLogger();
/*Sends 10 messages each at an interval of 10 seconds to show asynchronous message creation*/
MessageProducer producer = new MessageProducer(10, 1, TimeUnit.SECONDS);
/*Create a new client for the server address*/
HttpClient.newClient(socketAddress)
.enableWireLogging("msging-client", LogLevel.DEBUG)
.createGet("/ws")
.requestWebSocketUpgrade()
.doOnNext(resp -> logger.info(resp.toString()))
.flatMap(WebSocketResponse::getWebSocketConnection)
.flatMap(conn ->
conn.writeAndFlushOnEach(producer.getMessageStream())
.cast(WebSocketFrame.class)
.mergeWith(conn.getInput())
)
.retryWhen(errStream -> errStream.flatMap(err -> {
if (err instanceof IOException) {
return Observable.timer(1, TimeUnit.SECONDS);
}
return Observable.error(err);
}))
.filter(AcceptOnlyBinaryFramesFilter.INSTANCE)
.cast(BinaryWebSocketFrame.class)
.map(producer::acceptAcknowledgment)
.take(10)
.toBlocking()
.forEach(msgId -> logger.info("Received acknowledgment for message id => " + msgId.toString()));
}
}