April 2017
Intermediate to advanced
280 pages
6h 18m
English
Content preview from MQTT Essentials - A Lightweight IoT ProtocolBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Subscribing to topics in JavaScript
After a connection has been successfully established with the MQTT server, the specified callback in the this.mqttConnectOptions.onSuccess attribute will be executed, that is, the onConnectSuccess function. This function receives an invocationContext object as an argument. The code can access the object we assigned to this.mqttConnectOptions.invocationContext in invocationContext.invocationContext. Thus, the code can retrieve the instance of Paho.MQTT.Client, which established the connection with the MQTT server in the invocationContext.invocationContext.client attribute.
First, the onSuccess function updates the status text to indicate that the client is connected with the MQTT server. Then, the code saves ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.