Direct MQTT vs MQTT over WebSocket [closed]

Question

What are merits of MQTT over WebSocket compared to direct MQTT?

I'm considering using MQTT in my project and so I want to know why some people choose MQTT over WebSocket instead of direct MQTT.

Answer 1

You should only need to run MQTT over websockets if you intend to publish/subscribe to messages directly from within webapps (in page).

Basically I would run pure MQTT for everything and only add the websockets if you actually need it.

For all the non-browser languages the MQTT client libraries only use native MQTT. For Javascript there is both a pure MQTT library and the Paho in page library that uses websockets.

Edit: The firewall tunnelling use case is a valid reason to use MQTT over websockets and since writing this answer more of the none web/JavaScript client libraries have added support

Answer 2

Two main reasons for using MQTT over Websockets (which effectively means going over HTTP/HTTPS):

• Web apps (those running in a browser - e.g. written in JavaScript)
• Any other applications that don't want to use the 1883/8883 port and want to go over HTTP/HTTPS instead - this could be so that there is less of a chance of being blocked by a firewall (e.g. in a corporate network), as most firewalls will let HTTP traffic through

If you don't need or worry about the above, use "direct" MQTT:

• it is more efficient
• there are more client libraries for various languages that work with "direct" MQTT