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Which is true for MQTT topic?
In MQTT, the word topic refers to an UTF-8 string that the broker uses to filter messages for each connected client. The topic consists of one or more topic levels. Note that each topic must contain at least 1 character and that the topic string permits empty spaces. Topics are case-sensitive.
What is MQTT full form?
MQTT (MQ Telemetry Transport) is a lightweight open messaging protocol that provides resource-constrained network clients with a simple way to distribute telemetry information in low-bandwidth environments. While the TT in MQTT stands for Telemetry Transport, the MQ is in reference to a product called IBM MQ.
What makes a topic a topic in MQTT?
A topic only exists if a client has subscribed to it, or a broker has a retained or last will messages stored for that topic. This is a reserved topic and is used by most MQTT brokers to publish information about the broker. They are read-only topics for the MQTT clients.
How does the MQTT broker decide which message to send?
As we have already mentioned, the MQTT broker uses the topic of a message to decide which client receives which message. We also look at SYS-topics, which are special topics that reveal information about the broker itself. Be sure to watch our video about MQTT topics at the end of this blog post. Let’s get started.
Do you have to subscribe to all MQTT messages?
Do not subscribe to all messages on a broker by using an MQTT client and subscribing to a multi-level wildcard. Frequently, the subscribing client is not able to process the load of messages that results from this method (especially if you have a massive throughput).
How does the publish message work in MQTT V5?
Messages are acknowledged but not by the final receiver. In MQTTv5 the ability to publish a response topic was added in the publish message which allows you to implement the request/response pattern between clients that is common in Web applications.