paho.mqtt.cpp/examples/topic_publish.cpp

// topic_publish.cpp
//
// This is a Paho MQTT C++ client, sample application.
//
// It's an example of how to send messages as an MQTT publisher using the
// C++ asynchronous client interface using a 'topic' object to repeatedly
// send data to the same topic.
//
// The sample demonstrates:
//  - Connecting to an MQTT server/broker
//  - Publishing messages
//  - Use of the 'topic' class
//

/*******************************************************************************
 * Copyright (c) 2019-2023 Frank Pagliughi <fpagliughi@mindspring.com>
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v2.0
 * and Eclipse Distribution License v1.0 which accompany this distribution.
 *
 * The Eclipse Public License is available at
 *    http://www.eclipse.org/legal/epl-v20.html
 * and the Eclipse Distribution License is available at
 *   http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *    Frank Pagliughi - initial implementation and documentation
 *******************************************************************************/

#include <iostream>
#include <cstdlib>
#include <string>
#include <thread>	// For sleep
#include <atomic>
#include <chrono>
#include <cstring>
#include "mqtt/async_client.h"

using namespace std;

const string DFLT_SERVER_ADDRESS { "mqtt://localhost:1883" };

const string TOPIC { "test" };
const int QOS = 1;

const char* PAYLOADS[] = {
	"Hello World!",
	"Hi there!",
	"Is anyone listening?",
	"Someone is always listening.",
	nullptr
};

const auto TIMEOUT = std::chrono::seconds(10);

/////////////////////////////////////////////////////////////////////////////

int main(int argc, char* argv[])
{
	string address = (argc > 1) ? string(argv[1]) : DFLT_SERVER_ADDRESS;

	cout << "Initializing for server '" << address << "'..." << endl;
	mqtt::async_client cli(address, "");

	cout << "  ...OK" << endl;

	try {
		cout << "\nConnecting..." << endl;
		cli.connect()->wait();
		cout << "  ...OK" << endl;

		cout << "\nPublishing messages..." << endl;

		mqtt::topic top(cli, "test", QOS);
		mqtt::token_ptr tok;

		size_t i = 0;
		while (PAYLOADS[i]) {
			tok = top.publish(PAYLOADS[i++]);
		}
		tok->wait();	// Just wait for the last one to complete.
		cout << "OK" << endl;

		// Disconnect
		cout << "\nDisconnecting..." << endl;
		cli.disconnect()->wait();
		cout << "  ...OK" << endl;
	}
	catch (const mqtt::exception& exc) {
		cerr << exc << endl;
		return 1;
	}

 	return 0;
}