> 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/actions/group-communications/mqtt-publish.md).

# MQTT Publish

Publish a message to a topic on an MQTT broker using a connection previously opened with **MQTT Connect**.

Action available for the following 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>

<figure><img src="https://1614058754-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FJ5vDGuBZwhJDeu5Rq7Wt%2Fuploads%2FSqYIMdIONVJOZzcjVjgf%2Fimage.png?alt=media&amp;token=82fad50a-66f8-45dd-8be1-6d92a7448138" alt=""><figcaption></figcaption></figure>

## Parameters

* **MQTT ID** *\<numeric> -* The identifier of the MQTT connection to use. This must match the **Target MQTT ID** used in **MQTT Connect**.
* **Topic** *\<string> -* The topic to publish the message to (e.g. `sensors/temperature`).
* **Coded** *\<unquoted string> -* Defines whether the payload is a Base64 encoded binary value:
  * **Yes** - **Publish Data** is treated as Base64 encoded binary content and decoded before being sent.
  * **No** - **Publish Data** is sent as a plain text payload.
* **Publish Data** *\<string> -* The content of the message to publish.
* **Quality of Service** *\<unquoted string> -* The QoS level used to deliver the message:
  * **At most once** (QoS 0) - Message is sent once with no acknowledgment. It may be lost if the client or network fails.
  * **At least once** (QoS 1) - Message is delivered at least once. Duplicates are possible.
  * **Exactly once** (QoS 2) - Message is delivered exactly once. Slowest option but guarantees no loss or duplication.
* **Retain** *\<unquoted string> -* Defines whether the broker keeps the message as the last known good value for the topic:
  * **Yes** - The broker stores the message and delivers it to any new subscriber to this topic.
  * **No** - The message is delivered only to currently subscribed clients.