MQTTClient.unsubscribe()

Overview

Unsubscribes from a topic filter on a connected MQTT broker.

Added in version 2.1.13

Format

var mqttClient = new MQTTClient(options);

//...

mqttClient.unsubscribe(subscription, onSuccess, onFailure);

Value Description Type Required Notes
subscription An object or a string describing the subscription. String or Object Required If a string than the string represents the filter. Subscription object properties are described below.
onComplete A callback function that is called asynchronously if the subscribe completes. Function Optional When called, the first parameter is a Complete object as described below.
onError A callback function that is called asynchronously if the subscribe errors. Function Optional When called, the first parameter is an Error object as described below.

Subscription object properties

Value Description Type Required Notes
filter The topic filter. String Required May contain + symbol to represent a single intermediate level wildcard. May end with the # symbol to indicate a match with any further levels.

Complete object properties

Value Description Type

Notes
result A result code. Integer

Possible values:

•0 – Success

•17 – No subscription existed

•128 – Unspecified error

•131 – Implementation specific error

•135 – Not authorized

•143 – Topic filter invalid

•145 – Packet identifier in use

Error object properties

Value Description Type

Notes
message A message that describes the failure. String May be undefined.
type A category for the type of failure. String  

Example

Copy 
/* Displays a toast when a message is received on the "velocity/popup/toast" topic.
 * Unsubscribes after first toast.
 */

mqttClient = new MQTTClient({
    broker: "mqtt://mymqtt.example.com",
    subscribeTo: [
        {
            filter: "velocity/popup/toast",
            qos: 0,
            callback: function(message) {
                View.toast(message.payloadAsString, true);

                mqttClient.unsubscribe("velocity/popup/toast", function(complete) {
                    Logger.debug("unsubscribed: " + complete.result);
                }, function(error) {
                    Logger.warning("failed unsubscribing: " + (error.message || error.type));
                });
            }
        }
    ]
});

mqttClient.connect();