#460 Add missing sample 'async_consume_v5.cpp'

src/samples/async_consume_v5.cpp

@@ -0,0 +1,133 @@
+// async_consume_v5.cpp
+//
+// This is a Paho MQTT C++ client, sample application.
+//
+// This application is an MQTT consumer/subscriber using the C++
+// asynchronous client interface, employing the  to receive messages
+// and status updates.
+//
+// The sample demonstrates:
+//  - Connecting to an MQTT v5 server/broker.
+//  - Subscribing to a topic
+//  - Receiving messages through the consuming (queuing) API
+//
+
+/*******************************************************************************
+ * Copyright (c) 2013-2023 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 v1.0
+ * and Eclipse Distribution License v1.0 which accompany this distribution.
+ *
+ * The Eclipse Public License is available at
+ *    http://www.eclipse.org/legal/epl-v10.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 <cstring>
+#include <cctype>
+#include <thread>
+#include <chrono>
+#include "mqtt/async_client.h"
+
+using namespace std;
+
+const string SERVER_ADDRESS	{ "mqtt://localhost:1883" };
+const string CLIENT_ID		{ "PahoCppAsyncConsumeV5" };
+const string TOPIC 			{ "hello" };
+
+const int  QOS = 1;
+
+/////////////////////////////////////////////////////////////////////////////
+
+int main(int argc, char* argv[])
+{
+	// Create a client using MQTT v5
+	mqtt::create_options createOpts(MQTTVERSION_5);
+	mqtt::async_client cli(SERVER_ADDRESS, CLIENT_ID, createOpts);
+
+	auto connOpts = mqtt::connect_options_builder()
+		.properties({
+			{mqtt::property::SESSION_EXPIRY_INTERVAL, 604800}
+	    })
+		.clean_session(false)
+		.finalize();
+
+	try {
+		cli.set_connection_lost_handler([](const std::string&) {
+			cout << "*** Connection Lost ***" << endl;
+		});
+
+		cli.set_disconnected_handler([](const mqtt::properties&, mqtt::ReasonCode reason) {
+			cout << "*** Disconnected. Reason: " << reason << " ***" << endl;
+		});
+
+		// Start consumer before connecting to make sure to not miss messages
+
+		cli.start_consuming();
+
+		// Connect to the server
+
+		cout << "Connecting to the MQTT server..." << flush;
+		auto tok = cli.connect(connOpts);
+
+		// Getting the connect response will block waiting for the
+		// connection to complete.
+		auto rsp = tok->get_connect_response();
+
+		// Make sure we were granted a v5 connection.
+		if (rsp.get_mqtt_version() < MQTTVERSION_5) {
+			cout << "Did not get an MQTT v5 connection." << endl;
+			exit(1);
+		}
+
+		// If there is no session present, then we need to subscribe, but if
+		// there is a session, then the server remembers us and our
+		// subscriptions.
+		if (!rsp.is_session_present()) {
+			cout << "Session not present on broker. Subscribing." << endl;
+			cli.subscribe(TOPIC, QOS)->wait();
+		}
+
+		cout << "OK" << endl;
+
+		// Consume messages
+		// This just exits if the client is disconnected.
+		// (See some other examples for auto or manual reconnect)
+
+		cout << "Waiting for messages on topic: '" << TOPIC << "'" << endl;
+
+		while (true) {
+			auto msg = cli.consume_message();
+			if (!msg) break;
+			cout << msg->get_topic() << ": " << msg->to_string() << endl;
+		}
+
+		// If we're here, the client was almost certainly disconnected.
+		// But we check, just to make sure.
+
+		if (cli.is_connected()) {
+			cout << "\nShutting down and disconnecting from the MQTT server..." << flush;
+			cli.stop_consuming();
+			cli.disconnect()->wait();
+			cout << "OK" << endl;
+		}
+		else {
+			cout << "\nClient was disconnected" << endl;
+		}
+	}
+	catch (const mqtt::exception& exc) {
+		cerr << "\n  " << exc << endl;
+		return 1;
+	}
+
+ 	return 0;
+}
+