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@17:0811bdbdd78a, 2015-07-27 (annotated)

Committer:
icraggs
Date:
Mon Jul 27 09:16:08 2015 +0000
Revision:
17:0811bdbdd78a
Parent:
16:28d062c5522b
Child:
18:07a79d8f01c3
Make sure QoS 2 works

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 1:a1d5c7a6acbc 27
icraggs 17:0811bdbdd78a 28 #include "C12832.h"
icraggs 2:638c854c0695 29
icraggs 17:0811bdbdd78a 30 #if defined(TARGET_UBLOX_C027)
icraggs 17:0811bdbdd78a 31 #warning "Compiling for mbed C027"
icraggs 17:0811bdbdd78a 32 #include "C027.h"
icraggs 17:0811bdbdd78a 33 #elif defined(TARGET_LPC1768)
icraggs 17:0811bdbdd78a 34 #warning "Compiling for mbed LPC1768"
icraggs 17:0811bdbdd78a 35 #include "LPC1768.h"
icraggs 17:0811bdbdd78a 36 #elif defined(TARGET_K64F)
icraggs 17:0811bdbdd78a 37 #warning "Compiling for mbed K64F"
icraggs 17:0811bdbdd78a 38 #include "K64F.h"
icraggs 17:0811bdbdd78a 39 #endif
icraggs 17:0811bdbdd78a 40
icraggs 17:0811bdbdd78a 41 #define MQTTCLIENT_QOS2 1
icraggs 0:0cae29831d01 42
icraggs 8:a3e3113054a1 43 #include "MQTTEthernet.h"
icraggs 2:638c854c0695 44 #include "MQTTClient.h"
icraggs 2:638c854c0695 45
icraggs 2:638c854c0695 46 int arrivedcount = 0;
icraggs 2:638c854c0695 47
icraggs 8:a3e3113054a1 48
icraggs 9:5beb8609e9f7 49 void messageArrived(MQTT::MessageData& md)
icraggs 2:638c854c0695 50 {
icraggs 9:5beb8609e9f7 51 MQTT::Message &message = md.message;
icraggs 9:5beb8609e9f7 52 printf("Message arrived: qos %d, retained %d, dup %d, packetid %d\n", message.qos, message.retained, message.dup, message.id);
icraggs 9:5beb8609e9f7 53 printf("Payload %.*s\n", message.payloadlen, (char*)message.payload);
icraggs 2:638c854c0695 54 ++arrivedcount;
icraggs 17:0811bdbdd78a 55 lcd.cls();
icraggs 9:5beb8609e9f7 56 lcd.puts((char*)message.payload);
icraggs 2:638c854c0695 57 }
icraggs 0:0cae29831d01 58
icraggs 2:638c854c0695 59
icraggs 2:638c854c0695 60 int main(int argc, char* argv[])
icraggs 2:638c854c0695 61 {
icraggs 8:a3e3113054a1 62 MQTTEthernet ipstack = MQTTEthernet();
icraggs 17:0811bdbdd78a 63 float version = 0.5;
icraggs 2:638c854c0695 64 char* topic = "mbed-sample";
icraggs 2:638c854c0695 65
icraggs 17:0811bdbdd78a 66 lcd.cls();
icraggs 17:0811bdbdd78a 67 lcd.printf("HelloMQTT: version is %f\n", version);
icraggs 2:638c854c0695 68
icraggs 8:a3e3113054a1 69 MQTT::Client<MQTTEthernet, Countdown> client = MQTT::Client<MQTTEthernet, Countdown>(ipstack);
icraggs 3:7a6a899de7cc 70
icraggs 6:e4c690c45021 71 char* hostname = "m2m.eclipse.org";
icraggs 6:e4c690c45021 72 int port = 1883;
icraggs 17:0811bdbdd78a 73 lcd.cls();
icraggs 6:e4c690c45021 74 lcd.printf("Connecting to %s:%d\n", hostname, port);
icraggs 6:e4c690c45021 75 int rc = ipstack.connect(hostname, port);
icraggs 6:e4c690c45021 76 if (rc != 0)
icraggs 17:0811bdbdd78a 77 {
icraggs 17:0811bdbdd78a 78 lcd.cls();
icraggs 6:e4c690c45021 79 lcd.printf("rc from TCP connect is %d\n", rc);
icraggs 17:0811bdbdd78a 80 }
icraggs 6:e4c690c45021 81
icraggs 6:e4c690c45021 82 MQTTPacket_connectData data = MQTTPacket_connectData_initializer;
icraggs 6:e4c690c45021 83 data.MQTTVersion = 3;
icraggs 8:a3e3113054a1 84 data.clientID.cstring = "mbed-sample";
icraggs 12:086a9314e8a5 85 data.username.cstring = "testuser";
icraggs 12:086a9314e8a5 86 data.password.cstring = "testpassword";
icraggs 16:28d062c5522b 87 if ((rc = client.connect(data)) != 0)
icraggs 17:0811bdbdd78a 88 {
icraggs 17:0811bdbdd78a 89 lcd.cls();
icraggs 6:e4c690c45021 90 lcd.printf("rc from MQTT connect is %d\n", rc);
icraggs 17:0811bdbdd78a 91 }
icraggs 2:638c854c0695 92
icraggs 8:a3e3113054a1 93 if ((rc = client.subscribe(topic, MQTT::QOS1, messageArrived)) != 0)
icraggs 17:0811bdbdd78a 94 {
icraggs 17:0811bdbdd78a 95 lcd.cls();
icraggs 8:a3e3113054a1 96 lcd.printf("rc from MQTT subscribe is %d\n", rc);
icraggs 17:0811bdbdd78a 97 }
icraggs 2:638c854c0695 98
icraggs 2:638c854c0695 99 MQTT::Message message;
icraggs 0:0cae29831d01 100
icraggs 2:638c854c0695 101 // QoS 0
icraggs 2:638c854c0695 102 char buf[100];
icraggs 2:638c854c0695 103 sprintf(buf, "Hello World! QoS 0 message from app version %f\n", version);
icraggs 2:638c854c0695 104 message.qos = MQTT::QOS0;
icraggs 2:638c854c0695 105 message.retained = false;
icraggs 2:638c854c0695 106 message.dup = false;
icraggs 2:638c854c0695 107 message.payload = (void*)buf;
icraggs 2:638c854c0695 108 message.payloadlen = strlen(buf)+1;
icraggs 16:28d062c5522b 109 rc = client.publish(topic, message);
icraggs 12:086a9314e8a5 110 while (arrivedcount < 1)
icraggs 2:638c854c0695 111 client.yield(100);
icraggs 2:638c854c0695 112
icraggs 2:638c854c0695 113 // QoS 1
icraggs 2:638c854c0695 114 sprintf(buf, "Hello World! QoS 1 message from app version %f\n", version);
icraggs 2:638c854c0695 115 message.qos = MQTT::QOS1;
icraggs 2:638c854c0695 116 message.payloadlen = strlen(buf)+1;
icraggs 16:28d062c5522b 117 rc = client.publish(topic, message);
icraggs 12:086a9314e8a5 118 while (arrivedcount < 2)
icraggs 2:638c854c0695 119 client.yield(100);
icraggs 2:638c854c0695 120
icraggs 2:638c854c0695 121 // QoS 2
icraggs 2:638c854c0695 122 sprintf(buf, "Hello World! QoS 2 message from app version %f\n", version);
icraggs 2:638c854c0695 123 message.qos = MQTT::QOS2;
icraggs 2:638c854c0695 124 message.payloadlen = strlen(buf)+1;
icraggs 16:28d062c5522b 125 rc = client.publish(topic, message);
icraggs 12:086a9314e8a5 126 while (arrivedcount < 3)
icraggs 2:638c854c0695 127 client.yield(100);
icraggs 17:0811bdbdd78a 128
icraggs 17:0811bdbdd78a 129 if ((rc = client.unsubscribe(topic)) != 0)
icraggs 12:086a9314e8a5 130 {
icraggs 17:0811bdbdd78a 131 lcd.cls();
icraggs 17:0811bdbdd78a 132 lcd.printf("rc from unsubscribe was %d\n", rc);
icraggs 12:086a9314e8a5 133 }
icraggs 2:638c854c0695 134
icraggs 8:a3e3113054a1 135 if ((rc = client.disconnect()) != 0)
icraggs 17:0811bdbdd78a 136 {
icraggs 17:0811bdbdd78a 137 lcd.cls();
icraggs 17:0811bdbdd78a 138 lcd.printf("rc from disconnect was %d\n", rc);
icraggs 17:0811bdbdd78a 139 }
icraggs 2:638c854c0695 140
icraggs 2:638c854c0695 141 ipstack.disconnect();
icraggs 2:638c854c0695 142
sam_grove 5:4a257f6ac09a 143 lcd.cls();
icraggs 8:a3e3113054a1 144 lcd.printf("Version %.2f: finish %d msgs\n", version, arrivedcount);
icraggs 2:638c854c0695 145
icraggs 0:0cae29831d01 146 return 0;
icraggs 0:0cae29831d01 147 }