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@18:07a79d8f01c3, 2015-07-27 (annotated)

Committer:
icraggs
Date:
Mon Jul 27 09:30:31 2015 +0000
Revision:
18:07a79d8f01c3
Parent:
17:0811bdbdd78a
Child:
19:7f7aba7a4a8b
Make it easy to not use LCD screen, if you don't have one

Who changed what in which revision?

UserRevisionLine numberNew contents of line
icraggs 1:a1d5c7a6acbc 1 /*******************************************************************************
icraggs 17:0811bdbdd78a 2 * Copyright (c) 2014, 2015 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 17:0811bdbdd78a 15 * Ian Craggs - make sure QoS2 processing works, and add device headers
icraggs 1:a1d5c7a6acbc 16 *******************************************************************************/
icraggs 2:638c854c0695 17
icraggs 2:638c854c0695 18 /**
icraggs 2:638c854c0695 19 This is a sample program to illustrate the use of the MQTT Client library
icraggs 2:638c854c0695 20 on the mbed platform. The Client class requires two classes which mediate
icraggs 2:638c854c0695 21 access to system interfaces for networking and timing. As long as these two
icraggs 2:638c854c0695 22 classes provide the required public programming interfaces, it does not matter
icraggs 2:638c854c0695 23 what facilities they use underneath. In this program, they use the mbed
icraggs 2:638c854c0695 24 system libraries.
icraggs 2:638c854c0695 25
icraggs 2:638c854c0695 26 */
icraggs 18:07a79d8f01c3 27
icraggs 18:07a79d8f01c3 28 // change this to 0 to output messages to serial instead of LCD
icraggs 18:07a79d8f01c3 29 #define USE_LCD 1
icraggs 1:a1d5c7a6acbc 30
icraggs 18:07a79d8f01c3 31 #if USE_LCD
icraggs 17:0811bdbdd78a 32 #include "C12832.h"
icraggs 2:638c854c0695 33
icraggs 17:0811bdbdd78a 34 #if defined(TARGET_UBLOX_C027)
icraggs 17:0811bdbdd78a 35 #warning "Compiling for mbed C027"
icraggs 17:0811bdbdd78a 36 #include "C027.h"
icraggs 17:0811bdbdd78a 37 #elif defined(TARGET_LPC1768)
icraggs 17:0811bdbdd78a 38 #warning "Compiling for mbed LPC1768"
icraggs 17:0811bdbdd78a 39 #include "LPC1768.h"
icraggs 17:0811bdbdd78a 40 #elif defined(TARGET_K64F)
icraggs 17:0811bdbdd78a 41 #warning "Compiling for mbed K64F"
icraggs 17:0811bdbdd78a 42 #include "K64F.h"
icraggs 17:0811bdbdd78a 43 #endif
icraggs 17:0811bdbdd78a 44
icraggs 18:07a79d8f01c3 45 #define printf lcd.cls();lcd.printf
icraggs 18:07a79d8f01c3 46
icraggs 18:07a79d8f01c3 47 #endif
icraggs 18:07a79d8f01c3 48
icraggs 17:0811bdbdd78a 49 #define MQTTCLIENT_QOS2 1
icraggs 0:0cae29831d01 50
icraggs 8:a3e3113054a1 51 #include "MQTTEthernet.h"
icraggs 2:638c854c0695 52 #include "MQTTClient.h"
icraggs 2:638c854c0695 53
icraggs 2:638c854c0695 54 int arrivedcount = 0;
icraggs 2:638c854c0695 55
icraggs 8:a3e3113054a1 56
icraggs 9:5beb8609e9f7 57 void messageArrived(MQTT::MessageData& md)
icraggs 2:638c854c0695 58 {
icraggs 9:5beb8609e9f7 59 MQTT::Message &message = md.message;
icraggs 9:5beb8609e9f7 60 printf("Message arrived: qos %d, retained %d, dup %d, packetid %d\n", message.qos, message.retained, message.dup, message.id);
icraggs 9:5beb8609e9f7 61 printf("Payload %.*s\n", message.payloadlen, (char*)message.payload);
icraggs 2:638c854c0695 62 ++arrivedcount;
icraggs 2:638c854c0695 63 }
icraggs 0:0cae29831d01 64
icraggs 2:638c854c0695 65
icraggs 2:638c854c0695 66 int main(int argc, char* argv[])
icraggs 2:638c854c0695 67 {
icraggs 8:a3e3113054a1 68 MQTTEthernet ipstack = MQTTEthernet();
icraggs 17:0811bdbdd78a 69 float version = 0.5;
icraggs 2:638c854c0695 70 char* topic = "mbed-sample";
icraggs 2:638c854c0695 71
icraggs 18:07a79d8f01c3 72 printf("HelloMQTT: version is %f\n", version);
icraggs 2:638c854c0695 73
icraggs 8:a3e3113054a1 74 MQTT::Client<MQTTEthernet, Countdown> client = MQTT::Client<MQTTEthernet, Countdown>(ipstack);
icraggs 3:7a6a899de7cc 75
icraggs 6:e4c690c45021 76 char* hostname = "m2m.eclipse.org";
icraggs 6:e4c690c45021 77 int port = 1883;
icraggs 18:07a79d8f01c3 78 printf("Connecting to %s:%d\n", hostname, port);
icraggs 6:e4c690c45021 79 int rc = ipstack.connect(hostname, port);
icraggs 6:e4c690c45021 80 if (rc != 0)
icraggs 18:07a79d8f01c3 81 printf("rc from TCP connect is %d\n", rc);
icraggs 6:e4c690c45021 82
icraggs 6:e4c690c45021 83 MQTTPacket_connectData data = MQTTPacket_connectData_initializer;
icraggs 6:e4c690c45021 84 data.MQTTVersion = 3;
icraggs 8:a3e3113054a1 85 data.clientID.cstring = "mbed-sample";
icraggs 12:086a9314e8a5 86 data.username.cstring = "testuser";
icraggs 12:086a9314e8a5 87 data.password.cstring = "testpassword";
icraggs 16:28d062c5522b 88 if ((rc = client.connect(data)) != 0)
icraggs 18:07a79d8f01c3 89 printf("rc from MQTT connect is %d\n", rc);
icraggs 2:638c854c0695 90
icraggs 8:a3e3113054a1 91 if ((rc = client.subscribe(topic, MQTT::QOS1, messageArrived)) != 0)
icraggs 18:07a79d8f01c3 92 printf("rc from MQTT subscribe is %d\n", rc);
icraggs 2:638c854c0695 93
icraggs 2:638c854c0695 94 MQTT::Message message;
icraggs 0:0cae29831d01 95
icraggs 2:638c854c0695 96 // QoS 0
icraggs 2:638c854c0695 97 char buf[100];
icraggs 2:638c854c0695 98 sprintf(buf, "Hello World! QoS 0 message from app version %f\n", version);
icraggs 2:638c854c0695 99 message.qos = MQTT::QOS0;
icraggs 2:638c854c0695 100 message.retained = false;
icraggs 2:638c854c0695 101 message.dup = false;
icraggs 2:638c854c0695 102 message.payload = (void*)buf;
icraggs 2:638c854c0695 103 message.payloadlen = strlen(buf)+1;
icraggs 16:28d062c5522b 104 rc = client.publish(topic, message);
icraggs 12:086a9314e8a5 105 while (arrivedcount < 1)
icraggs 2:638c854c0695 106 client.yield(100);
icraggs 2:638c854c0695 107
icraggs 2:638c854c0695 108 // QoS 1
icraggs 2:638c854c0695 109 sprintf(buf, "Hello World! QoS 1 message from app version %f\n", version);
icraggs 2:638c854c0695 110 message.qos = MQTT::QOS1;
icraggs 2:638c854c0695 111 message.payloadlen = strlen(buf)+1;
icraggs 16:28d062c5522b 112 rc = client.publish(topic, message);
icraggs 12:086a9314e8a5 113 while (arrivedcount < 2)
icraggs 2:638c854c0695 114 client.yield(100);
icraggs 2:638c854c0695 115
icraggs 2:638c854c0695 116 // QoS 2
icraggs 2:638c854c0695 117 sprintf(buf, "Hello World! QoS 2 message from app version %f\n", version);
icraggs 2:638c854c0695 118 message.qos = MQTT::QOS2;
icraggs 2:638c854c0695 119 message.payloadlen = strlen(buf)+1;
icraggs 16:28d062c5522b 120 rc = client.publish(topic, message);
icraggs 12:086a9314e8a5 121 while (arrivedcount < 3)
icraggs 2:638c854c0695 122 client.yield(100);
icraggs 17:0811bdbdd78a 123
icraggs 17:0811bdbdd78a 124 if ((rc = client.unsubscribe(topic)) != 0)
icraggs 12:086a9314e8a5 125 {
icraggs 17:0811bdbdd78a 126 lcd.cls();
icraggs 18:07a79d8f01c3 127 printf("rc from unsubscribe was %d\n", rc);
icraggs 12:086a9314e8a5 128 }
icraggs 2:638c854c0695 129
icraggs 8:a3e3113054a1 130 if ((rc = client.disconnect()) != 0)
icraggs 17:0811bdbdd78a 131 {
icraggs 17:0811bdbdd78a 132 lcd.cls();
icraggs 18:07a79d8f01c3 133 printf("rc from disconnect was %d\n", rc);
icraggs 17:0811bdbdd78a 134 }
icraggs 2:638c854c0695 135
icraggs 2:638c854c0695 136 ipstack.disconnect();
icraggs 2:638c854c0695 137
icraggs 18:07a79d8f01c3 138 printf("Version %.2f: finish %d msgs\n", version, arrivedcount);
icraggs 2:638c854c0695 139
icraggs 0:0cae29831d01 140 return 0;
icraggs 0:0cae29831d01 141 }