MQTT Keep Alive And Client Takeover | MQTT Essentials Part 11

Welcome to the MQTT Essentials Video Series Part 11.
In the new episode of MQTT Essentials Series, we will talk about MQTT Keep Alive and Client Takeover.

MQTT Keep Alive and Client Takeover are two concepts to circumvent the "half-open TCP Connection" state.

Although MQTT is a very reliable and secure way to transfer data, it still can happen that the transfer between communication parties gets out of sync. If an MQTT client disconnects ungracefully and the MQTT broker is not notified, and is still under the impression of an existing TCP connection, the half-open TCP connection scenario occurs: one client disconnected, the other client is not aware of this.

👉 What is the Keep Alive mechanism?
Keep Alive defines the maximum length of time a broker and a client may have no communication between each other. When this specified length of time is exceeded, the broker will close the connection. To prevent this, the client can send a PINGREQ message within the Keep Alive period, to indicate the connection is still alive. When the broker receives the PINGREQ message, it responds with a PINGRESP package for confirmation. PINGREQ and PINGRESP do not contain a payload.

👉 What is Client Takeover?
When a client disconnects it will most likely try to reconnect. For example: a car driving into a tunnel will try to reconnect to the broker after it comes out of the tunnel. If the broker detects the half-open TCP connection and receives packets with the same ClientId, it will perform a Client Takeover. It will connect to the "new" client using this ClientId, and disconnect the "old" client. This procedure is called Client Takeover.

👉 Best practices
always use unique ClientIds
authenticate clients to prevent unwanted Client Takeover

** Chapters / Table of Contents **
00:00 Introduction to Keep Alive and Client Takeover in MQTT
01:26 Keep Alive in MQTT
03:05 Client Takeover in MQTT
04:10 Best Practices of Keep Alive and Client Takeover in MQTT
05:38 End of MQTT Essentials series - Announcing MQTT 5 Essentials

👉 If you missed Part 1 - What is MQTT, watch it now:    • What is MQTT | MQTT Essentials Part 1  

👉 We also explain the Keep Alive and Client Takeover in MQTT in detail in the HiveMQ blog here: https://bit.ly/3gcq88U

👉 If you would like to know more about MQTT security in particular we recommend our MQTT Security Fundamentals: https://www.hivemq.com/mqtt-security-...

👉 We also explain the core of MQTT concepts, its features, and other essential information on the HiveMQ blog: https://bit.ly/3F7l2pm

👉 Get your own MQTT Essentials in a comprehensive, free E-Book: https://bit.ly/3D17jhJ

👉 To know about HiveMQ: https://bit.ly/3ooK4uc

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👉 This was the last part of our MQTT Essentials. Watch out for our next video series on MQTT Monday focussing on MQTT 5:    • What is MQTT 5 and How Does It Work? | MQT...  

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