mqtt intro short
- 2. What is MQTT(S) ? • Very popular in IoT devices for pub/sub data • Open protocol and Standard ( no fees ) • Very Simple to implement as a socket TCP service – Small devices and IoT ready sensors uses this protocol (mainly) – Low overhead, low bandwidth use • Robustness – Suitable for mobile devices / unreliable connections ( QoS selectable ,Retained messages , Last will…) MQTT: Message Queuing Telemetry Transport
- 3. About MQTT… • MQTT Server ( usually called “Broker”) is a service that may run in a cloud or in your local infrastructure. • The server is responsible for receiving all messages, filtering them, manage the client connections and delivering the message to all subscribed clients. • The server may handle thousands of concurrently connected MQTT clients. The capacity depends of the service / network capacity you hire . MQTT Server
- 4. MQTT Server About MQTT… • MQTT Servers can be bridged each other in order to exchange and grow easily. • Devices that are connected to MQTT server hosted in a Cloud server may include extra integrated services • Big Data Storage • Analytics • Dashboards, Reports, etc • Notifications, alarms, events • Machine learning • Decisions • Predictions… MQTT Server
- 5. MQTT Main feature M2M “unlimited*” connections Just one connection (to Server) ..is shared to hundreds or thousands* MQTT Server *Depends of the Server/ cloud server clients capacity
- 6. Some MQTT brokers • Mosquitto (popular) • Apache ActiveMQ • Apollo MQTT • JoramMQ • RabbitMQ • VerneMQ • … Performance & features comparison: http://www.scalagent.com/IMG/pdf/Benchmark_MQTT_servers-v1-1.pdf
- 7. MQTT Basic Concepts Find a very handful tutorial to learn about MQTT at https://www.hivemq.com/blog/mqtt-essentials/
- 8. How does it share the data? • All data in MQTT has to be published under a TOPIC* in order to address to the subscribers Tank/Pressure/#Tank/Temperature/ Publisher Tank/Temperature/# Subscribers MQTT Server
- 9. MQTT pub/sub concept *MQTT Server Publish: Temperature Humidity Subscribe: Temperature Humidity Publish: Air Pressure Subscribe: Fan Control Air Pressure Subscribe: Fan Control Fan Status Temperature Humidity Air Pressure Publish: Fan Control Publish: Fan Status *Server can be local or remote (i.e. cloud service)
- 10. Quality of Service What is Quality of Service? • A Sender and Receiver agrees a Quality of Service level during publish and subscription, that guarantees delivering / receiving a message. • MQTT offers 3 QoS levels : • At most once (QoS0) • At least once (QoS1) • Exactly once (QoS2) MQTT Server Qualityofservice
- 11. Last Will / Testament Message • When a MQTT client connects to MQTT server, it may deliver a Last Will message (LWT) that is delivered to the other clients, when it disconnects from the server. • LWT message is set by the client when it connects to server. It is specified by a <LWT Topic> & <LWT message>. In order to receive a LWT message , a client has to be subscribed to the LWT topic • It may be used to notice to interested subscribers a MQTT client connection loss. LWT/Is_gone MQTT Server LWT/Is_gone LWT/Is_gone LWT/Is_gone Subs.LWT/ Subs.LWT/ Bye!
- 12. Retained messages <retained>Temp/23 MQTT Server <retained>Temp/23 23 SUSBSCRIBE Temp/ • A retained message will be stored by the MQTT server, even without subscribers listening. • The server will store the last retained message , only one retained message per topic. New retained message will overwrite the last one. • In this way , the receiver will get the message immediately after subscribing, without waiting to publisher to send the last value
- 13. Persistent Session ( clean session) • When a persistent session starts ,the MQTT server stores* relevant information for the session such: • Existence of a session , even if there are no subscriptions • All existing subscriptions • All messages in QoS1 /2, not confirmed by the client • All new QoS1/2 messages, while the client missed while it was offline • All received QoS2 messages, which are not yet confirmed from the client • A MQTTclient may use a Persistent session to agree to the Server that has to store the undelivered/ unconfirmed messages (in QoS1 and QoS2 only) MQTT Server
- 14. Keep Alive • A Keep Alive is a of timeout agreed from Client to Server, when client connects to MQTT server. • If the Server doesn’t receive any message from a client within the Keepalive time , server will drop the connection to the client . • In this case , Client should connect again in order to publish data. • This feature helps to close automatically inactive connections, releasing resources at the server MQTT Server
- 15. MQTT library
- 16. Library structure • It can be used a regular Internet Connection or a Local network • 3 FBs ( so far) to Connect, Publish & Subscribe to a MQTT broker
- 17. Message queue / buffer Operation concept MQTT ServerPublish instances Subscribe Instances MQTT Client This method allow to queue several messages from different datasources ( devices, variables, etc.. ) that are updated at different timing.
- 18. MQTTPublish Topic/Message Publish Example • By using a library to collect NJ data in a string variable , then calling to a MQTTpublish instance Message:SlaveData SlaveData= { "Temperature": 98.7, "Pressure": 1568, "PH": 7, "Pump": true, "Heater": false } MQTT Server Topic:Variables • Temperature • Pressure • PH • Pump • heater
- 19. Subscription example • NJ is subscribed to the topic Meteo/temperature/# from a sensor at home: MQTT Server Subscriber Publisher Meteo/temperature/ Meteo/temperature/21.8
- 20. JSON data format
- 21. The JSON data format • JSON (JavaScript Object Notation) is a popular data format at IoT used for data exchange. • Compared to XML : – Lightweight – Structured for natural reading and easy parsing
- 22. The JSON data format { "TimeStamp":"2017-11-08T15:37:58.926Z", "Temperature": 98.7, "Pressure": 1568, "Pump": true, } • A JSON data structure consist on one or more pairs of names and values, separated by comma ; and delimited by keys {..}. • It may include several types such numeric, boolean, text, date,.. as an structure • A JSON may include a Object definition for a key, and it may nest objects and arrays . {“Sensors”: {“location”:”Bathroom”,”Measure”:88.5,”Status”:TRUE}; {“location”:”Livingroom”,”Measure”:44.5,”Status”:FALSE}; {“location”:”Bedroom”,”Measure”:32.8,”Status”:FALSE}; {“location”:”Garage”,”Measure”:66.1,”Status”:TRUE} } {“Process”: { "TimeStamp":"2017-11-08T15:37:58.926Z", "Temperature": 98.7, "Pressure": 1568, "Pump": true } } { Machine: { Production: 55604, Rejected: 34, ProductionSpeed: 134, Status: { OEE: 91,2, OnProdution: TRUE, Hours: 1255.3 } } }
- 23. JSON library : use it with MQTT • MQTT protocol accept any type of data format • However , JSON is convenient format and compatible for IoT devices • We made a library to convert Sysmac variables to JSON string { "TimeStamp":"2017-11-08T15:37:58.926Z", "Stage":"On Preparation", "Temperature": 98.7, "Pressure": 1568, "PH": 7, "Pump": true, "Heater": false }
- 24. Collect data in structured way (JSON)… …and send it by MQTT !
- 25. MQTT + JSON: Application example • Machine / process supervision from a dashboard
- 26. The example below shows a conversion from variables to JSON strings , from different datasources ( at different locations), that are sent under MQTT Topics , and finally are shown in a dashboard:
- 27. Movie
- 28. Other application examples for MQTT library
- 29. Application example (1) • Single client is connected to a remote MQTT broker, by using a 4G modem/router trough VPN connection • Typical application for monitoring, alarm triggering, maintenance… MQTT Server MQTTPublish Topic/Message VPN MQTTSubscribe Topic/Message 3G/4G
- 30. Application example (2) • The clients are connected to a local MQTT broker • The broker manages the connections and published messages, and delivers to the subscribers
- 31. Application example (3) • In a Factory, MQTT clients shares messages between them across the local MQTT broker • In addition, the broker bridges to a external Cloud Service • The bridged connection can be secured from the local broker
- 32. TLS/SSL Bridged connection • Two or more factories can be connected from bridged connections to a global remote MQTT broker ( cloud service). • The global MQTT broker can deliver a message from any station to another, bridging both networks • On the Cloud Service, we can use the received data for analysis, storage, etc
- 33. Questions?
- 34. Thank You !
Editor's Notes
- #3: MC + PLC All in one