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mqtt_subscribe
Subscribes the client to a topic.
C Language
int mqtt_subscribe( MQTT handle, const char* topic);
| Example | MQTT Vuser Functions |
Arguments
| Name | Comments |
|---|---|
| handle | The MQTT client handle returned by mqtt_create. |
| topic | The destination topic as a null-terminated string. The topic can contain wildcards. Examples: |
General
mqtt_subscribe subscribes the client to a topic or a set of topics that match the wildcard. The broker sends messages published on these topics automatically.
If the connection is lost during mqtt_subscribe, the client tries to subscribe again after reconnection.
If invalid arguments are passed, the Vuser aborts, even if Continue on error is set.
Return Values
MQTT_SUCCESS or MQTT_FAIL
Parameterization
Standard parameterization is available for this function.
Example
/* Subscribe to the topics matching the wildcard "sensors/temperature/#"*/
mqtt_subscribe(client, "sensors/temperature/#");
/* Now the client will receive messages to subscribed topics */
/* Unsubscribe from the topic "sensors/temperature/surface/3" */
mqtt_unsubscribe(client, "sensors/temperature/surface/3");
/* Now the client will receive messages from all subscriptions except for "sensors/temperature/surface/3" */
