> For the complete documentation index, see [llms.txt](https://doc.sysdevmobile.com/kalipso/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.sysdevmobile.com/kalipso/documentation/controls/events/mqtt-message-received.md).

# MQTT Message received

This event is triggered when a message is received on a topic that was subscribed to with the [MQTT Subscribe](/kalipso/documentation/actions/group-communications/mqtt-subscribe.md) action.

When this event fires, the target variables defined in the [MQTT Connect](/kalipso/documentation/actions/group-communications/mqtt-connect.md) action are automatically updated with the details of the received message:

* **Target Notification MQTT ID** - The identifier of the MQTT connection that received the message. Useful to distinguish between messages when multiple MQTT connections are open at the same time.
* **Target Notification Topic** - The topic the message was published to. Useful when the subscription uses a wildcard (`+` or `#`) and you need to know which specific topic the message came from.
* **Target Notification Payload** - The content of the message.

Use this event to handle the incoming message — for example, parse the payload, update the UI, or store the data locally.

{% hint style="info" %}
To use this event, you must first open a connection with [MQTT Connect](/kalipso/documentation/actions/group-communications/mqtt-connect.md) and subscribe to at least one topic with [MQTT Subscribe](/kalipso/documentation/actions/group-communications/mqtt-subscribe.md).
{% endhint %}

## Supported operating systems

<figure><img src="https://1614058754-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FJ5vDGuBZwhJDeu5Rq7Wt%2Fuploads%2Fgit-blob-7a7ab3f3fc74afcaab1e0810f419316203cc49e1%2F01_Supported_OS.png?alt=media" alt="OS Supported: Android, iOS, Win, Win32"><figcaption></figcaption></figure>