MQTT

Message Queue for telemetry transport

Created by Disk_91 / @disk_91

You know Facebook Messenger ?

Do you know what is hapening when you click on send ?

What are mobile and IoT challenges ?

small bandwith networks (3G,Edge,GPRS)
not reliable network (tunnel, building)
filtering equipements (Nat, firewalls)
push notification (incoming messages, config)
small and portable (arm, x86, java, C, C#, js)

Why Mqtt is a solution ?

Network efficient - 10KB / hour
Reliable - Manage QoS
Build over TCP
Manage publish & subscribe
Implemented on every platform and languages

MQTT architecture

One on many Architecture

Broker is the central communication point

OpenSource server : Mosquitto
SaaS server : CloudMqtt.com based on mosquitto
Appliances : Datapower message sight to process 13M message / sec

Run the server !

# ./mosquitto

Client side

Client is maintaining open communication with broker
Client is publishing messages over topics
Client is subscribing to topics
Client implementations :

Eclipse Paho

Java, C, Javascript

dotNET, Objective-C, C++
Ruby, tcl, perl, rexx, pyhton, php, lua, dart, actionscript
Platform - Arduino, mbed, android, raspberry ...

Communication mode

One to One
One to Many
Many to One
Many to Many

Client sample code

				
void on_message(struct mosquitto *m, void *user_data, const struct mosquitto_message *msg) {
    fprintf(stderr, "Message from %s is %s\n", msg->topic, (char*)msg->payload);
}

int main(int argc, char **argv) {
    struct mosquitto *client;  int ret;
    mosquitto_lib_init();
    client = mosquitto_new("client-id", true, NULL);
    ret = mosquitto_connect(client, "127.0.0.1", 1883, 60);
    ret = mosquitto_subscribe(client, NULL, "my/topic/to/subscribe", 0);
    mosquitto_message_callback_set(client, on_message);
    while (MOSQ_ERR_SUCCESS == mosquitto_loop(client, -1, 1));
}

Let's talk a little bit more about MQTT

Mqtt has been developped by IBM and Arcom/Eurotech in the late 90's
Since 2011 adopted by Eclipse Fundation as part of M2M strategy.
Mqtt is now becoming an OASIS standard.

Now take a look to some details

Message format
Topics
QoS
Security

Message format

Messages are plain text... use what you want!

				
#!/usr/bin/python
import mosquitto
client = mosquitto.Mosquitto("test-client")
client.connect("127.0.0.1")
client.publish("my/topic", "{\"type\":\"integer\",\"value\":\"5\"}", 1)
client.publish("my/topic", "Hello world", 1)

Maximum message size is 256MB

Topics

Basically a topic is a queue
Tree organization of group of sensors
Like house / floor / room / sensor
Allows to design filter easily with Wildcard "+" and "#"
Anyone can publish in one topic or more
Anyone can subscribe to a topic or more

QoS

QoS0 - At most one delivery, message can be lost
QoS1 - At least one delivery
QoS2 - Exactly one delivery
Means MQTT stack manages resubmission regarding QoS

Security

Security is made at topic level - rights & Authentification
Level 0 - no security
Level 1 - Simple user / password security
Level 2 - SLL communication / authentication

Demo time

Why choosing MQTT

Questions