MQTT / Mbed OS HelloMQTT

Sample MQTT program - simple send and receive

Dependencies:   C12832 MQTT

Dependents:   MQTT_G_SENSOR

This program and the MQTT libraries it uses are part of the EclipseTM Paho project; specifically the embedded client.

This example and API are working, but are still in progress. Please give us your feedback.

HelloMQTT is an example of using the MQTT API. The MQTT API is portable across network interface stacks. MQTT is designed to be used with TCP/IP, but any transport with similar characteristics should be suitable.

HelloMQTT uses the NetworkInterface APIs in mbed OS 5 to show how this works. The MQTT library contains an MQTTNetwork.h header, which is a wrapper around the mbed networking interface. To switch between connectivity methods (the default is Ethernet) the easy-connect library is provided in this example application. You can change the connectivity method in mbed_app.json.

Adding new connectivity methods to the program is trivial, as long as they implement the mbed OS 5 NetworkStack API.

main.cpp@8:a3e3113054a1, 2014-05-20 (annotated)

Committer:
icraggs
Date:
Tue May 20 15:08:05 2014 +0000
Revision:
8:a3e3113054a1
Parent:
7:3de634f2d40c
Child:
9:5beb8609e9f7
Refactoring headers

Who changed what in which revision?

UserRevisionLine numberNew contents of line
icraggs 1:a1d5c7a6acbc 1 /*******************************************************************************
icraggs 1:a1d5c7a6acbc 2 * Copyright (c) 2014 IBM Corp.
icraggs 1:a1d5c7a6acbc 3 *
icraggs 1:a1d5c7a6acbc 4 * All rights reserved. This program and the accompanying materials
icraggs 1:a1d5c7a6acbc 5 * are made available under the terms of the Eclipse Public License v1.0
icraggs 1:a1d5c7a6acbc 6 * and Eclipse Distribution License v1.0 which accompany this distribution.
icraggs 1:a1d5c7a6acbc 7 *
icraggs 1:a1d5c7a6acbc 8 * The Eclipse Public License is available at
icraggs 1:a1d5c7a6acbc 9 * http://www.eclipse.org/legal/epl-v10.html
icraggs 1:a1d5c7a6acbc 10 * and the Eclipse Distribution License is available at
icraggs 1:a1d5c7a6acbc 11 * http://www.eclipse.org/org/documents/edl-v10.php.
icraggs 1:a1d5c7a6acbc 12 *
icraggs 1:a1d5c7a6acbc 13 * Contributors:
icraggs 1:a1d5c7a6acbc 14 * Ian Craggs - initial API and implementation and/or initial documentation
icraggs 1:a1d5c7a6acbc 15 *******************************************************************************/
icraggs 2:638c854c0695 16
icraggs 2:638c854c0695 17 /**
icraggs 2:638c854c0695 18 This is a sample program to illustrate the use of the MQTT Client library
icraggs 2:638c854c0695 19 on the mbed platform. The Client class requires two classes which mediate
icraggs 2:638c854c0695 20 access to system interfaces for networking and timing. As long as these two
icraggs 2:638c854c0695 21 classes provide the required public programming interfaces, it does not matter
icraggs 2:638c854c0695 22 what facilities they use underneath. In this program, they use the mbed
icraggs 2:638c854c0695 23 system libraries.
icraggs 2:638c854c0695 24
icraggs 2:638c854c0695 25 */
icraggs 1:a1d5c7a6acbc 26
icraggs 2:638c854c0695 27
sam_grove 5:4a257f6ac09a 28 #include "C12832.h"
sam_grove 5:4a257f6ac09a 29 C12832 lcd(p5, p7, p6, p8, p11);
icraggs 0:0cae29831d01 30
icraggs 8:a3e3113054a1 31 #include "MQTTEthernet.h"
icraggs 2:638c854c0695 32 #include "MQTTClient.h"
icraggs 2:638c854c0695 33
icraggs 2:638c854c0695 34 int arrivedcount = 0;
icraggs 2:638c854c0695 35
icraggs 8:a3e3113054a1 36
icraggs 2:638c854c0695 37 void messageArrived(MQTT::Message* message)
icraggs 2:638c854c0695 38 {
sam_grove 5:4a257f6ac09a 39 lcd.cls();
sam_grove 5:4a257f6ac09a 40 lcd.locate(0,3);
sam_grove 5:4a257f6ac09a 41 printf("Message arrived: qos %d, retained %d, dup %d, packetid %d\n", message->qos, message->retained, message->dup, message->id);
sam_grove 5:4a257f6ac09a 42 printf("Payload %.*s\n", message->payloadlen, (char*)message->payload);
icraggs 2:638c854c0695 43 ++arrivedcount;
sam_grove 5:4a257f6ac09a 44 lcd.puts((char*)message->payload);
icraggs 2:638c854c0695 45 }
icraggs 0:0cae29831d01 46
icraggs 2:638c854c0695 47
icraggs 2:638c854c0695 48 int main(int argc, char* argv[])
icraggs 2:638c854c0695 49 {
icraggs 8:a3e3113054a1 50 MQTTEthernet ipstack = MQTTEthernet();
icraggs 8:a3e3113054a1 51 float version = 0.46;
icraggs 2:638c854c0695 52 char* topic = "mbed-sample";
icraggs 2:638c854c0695 53
icraggs 2:638c854c0695 54 lcd.printf("Version is %f\n", version);
sam_grove 5:4a257f6ac09a 55 printf("Version is %f\n", version);
icraggs 2:638c854c0695 56
icraggs 8:a3e3113054a1 57 MQTT::Client<MQTTEthernet, Countdown> client = MQTT::Client<MQTTEthernet, Countdown>(ipstack);
icraggs 3:7a6a899de7cc 58
icraggs 6:e4c690c45021 59 char* hostname = "m2m.eclipse.org";
icraggs 6:e4c690c45021 60 int port = 1883;
icraggs 6:e4c690c45021 61 lcd.printf("Connecting to %s:%d\n", hostname, port);
icraggs 6:e4c690c45021 62 int rc = ipstack.connect(hostname, port);
icraggs 6:e4c690c45021 63 if (rc != 0)
icraggs 6:e4c690c45021 64 lcd.printf("rc from TCP connect is %d\n", rc);
icraggs 6:e4c690c45021 65
icraggs 6:e4c690c45021 66 MQTTPacket_connectData data = MQTTPacket_connectData_initializer;
icraggs 6:e4c690c45021 67 data.MQTTVersion = 3;
icraggs 8:a3e3113054a1 68 data.clientID.cstring = "mbed-sample";
icraggs 8:a3e3113054a1 69 if ((rc = client.connect(&data)) != 0)
icraggs 6:e4c690c45021 70 lcd.printf("rc from MQTT connect is %d\n", rc);
icraggs 2:638c854c0695 71
icraggs 8:a3e3113054a1 72 if ((rc = client.subscribe(topic, MQTT::QOS1, messageArrived)) != 0)
icraggs 8:a3e3113054a1 73 lcd.printf("rc from MQTT subscribe is %d\n", rc);
icraggs 2:638c854c0695 74
icraggs 2:638c854c0695 75 MQTT::Message message;
icraggs 0:0cae29831d01 76
icraggs 2:638c854c0695 77 // QoS 0
icraggs 2:638c854c0695 78 char buf[100];
icraggs 2:638c854c0695 79 sprintf(buf, "Hello World! QoS 0 message from app version %f\n", version);
icraggs 2:638c854c0695 80 message.qos = MQTT::QOS0;
icraggs 2:638c854c0695 81 message.retained = false;
icraggs 2:638c854c0695 82 message.dup = false;
icraggs 2:638c854c0695 83 message.payload = (void*)buf;
icraggs 2:638c854c0695 84 message.payloadlen = strlen(buf)+1;
icraggs 2:638c854c0695 85 rc = client.publish(topic, &message);
icraggs 2:638c854c0695 86 while (arrivedcount == 0)
icraggs 2:638c854c0695 87 client.yield(100);
icraggs 2:638c854c0695 88
icraggs 2:638c854c0695 89 // QoS 1
icraggs 2:638c854c0695 90 sprintf(buf, "Hello World! QoS 1 message from app version %f\n", version);
icraggs 2:638c854c0695 91 message.qos = MQTT::QOS1;
icraggs 2:638c854c0695 92 message.payloadlen = strlen(buf)+1;
icraggs 2:638c854c0695 93 rc = client.publish(topic, &message);
icraggs 2:638c854c0695 94 while (arrivedcount == 1)
icraggs 2:638c854c0695 95 client.yield(100);
icraggs 2:638c854c0695 96
icraggs 2:638c854c0695 97 // QoS 2
icraggs 2:638c854c0695 98 sprintf(buf, "Hello World! QoS 2 message from app version %f\n", version);
icraggs 2:638c854c0695 99 message.qos = MQTT::QOS2;
icraggs 2:638c854c0695 100 message.payloadlen = strlen(buf)+1;
icraggs 2:638c854c0695 101 rc = client.publish(topic, &message);
icraggs 2:638c854c0695 102 while (arrivedcount == 2)
icraggs 2:638c854c0695 103 client.yield(100);
icraggs 2:638c854c0695 104
icraggs 8:a3e3113054a1 105 if ((rc = client.unsubscribe(topic)) != 0)
sam_grove 5:4a257f6ac09a 106 printf("rc from unsubscribe was %d\n", rc);
icraggs 2:638c854c0695 107
icraggs 8:a3e3113054a1 108 if ((rc = client.disconnect()) != 0)
sam_grove 5:4a257f6ac09a 109 printf("rc from disconnect was %d\n", rc);
icraggs 2:638c854c0695 110
icraggs 2:638c854c0695 111 ipstack.disconnect();
icraggs 2:638c854c0695 112
sam_grove 5:4a257f6ac09a 113 lcd.cls();
sam_grove 5:4a257f6ac09a 114 lcd.locate(0,3);
icraggs 8:a3e3113054a1 115 lcd.printf("Version %.2f: finish %d msgs\n", version, arrivedcount);
sam_grove 5:4a257f6ac09a 116 printf("Finishing with %d messages received\n", arrivedcount);
icraggs 2:638c854c0695 117
icraggs 0:0cae29831d01 118 return 0;
icraggs 0:0cae29831d01 119 }