---
alias: user-guide-automation-task-core-messagebus-send
tags:
- automation tasks
description: "This task sends a message to a message bus subject, either as a notification or as a request that waits for a reply"
---

# Send Message Bus Message

:iot-messagebus-send-lg:

The Send Message Bus Message task sends a message to a message bus subject. The message is either a notification (fire and forget) or a request that waits for a reply.

![Screenshot showing the Send Message Bus Message task with its inputs and outputs.](../images/messagebus_send.png)

## Details

| Fields            | Details                                                                            |
| ----------------- | ---------------------------------------------------------------------------------- |
| Scope             | Connect IoT <br> Data Platform <br> Enterprise Integration <br> Factory Automation |
| Workflow          | Data flow <br> Control flow                                                        |
| `IsProtocol` flag | :material-close:{style="color:#EF5350"}                                            |

## Inputs

| Name        | Data Type | Description                                                                                            |
| ----------- | --------- | ------------------------------------------------------------------------------------------------------ |
| MessageType | `String`  | Type of message to send: `Notification` or `Request`. Overrides the **Message Type** setting.          |
| Subject     | `String`  | Message bus subject to send the message to. Overrides the **Subject** setting.                         |
| Message     | `Object`  | Message to send. Overrides the **Message** setting.                                                    |
| Timeout     | `Integer` | Maximum time, in milliseconds, to wait for a reply. Only available when the message type is `Request`. |
| Activate    | `any`     | Activates the task.                                                                                    |

## Outputs

| Name    | Data Type | Description                                                                         |
| ------- | --------- | ----------------------------------------------------------------------------------- |
| Reply   | `Object`  | Reply received for the request. Only available when the message type is `Request`. |
| Success | `Boolean` | Emits `true` when the message is sent or, for a request, when the reply arrives.    |
| Error   | `Error`   | Error that occurred during the processing of this task.                             |

## Settings

On the `General` tab, the `Message` section has the following settings:

| Name         | Data Type | Default        | Description                                                                                                     |
| ------------ | --------- | -------------- | --------------------------------------------------------------------------------------------------------------- |
| Message Type | `Enum`    | `Notification` | `Notification` sends the message without waiting for a reply. `Request` sends the message and waits for a reply. |
| Subject      | `String`  |                | Message bus subject to send the message to.                                                                     |
| Message      | `Object`  | `{}`           | Message to send using the message bus.                                                                          |
| Timeout      | `Integer` | `60000`        | Maximum time, in milliseconds, to wait for a reply. Only available when the message type is `Request`.          |

## Behavior

When activated, the task sends the message to the configured subject. Values received on the inputs take precedence over the settings.

- With the `Notification` message type, the task publishes the message and emits `true` on the **Success** output. It does not wait for a reply.
- With the `Request` message type, the task sends the message and waits for a reply for up to **Timeout** milliseconds. When the reply arrives, the task emits it on the **Reply** output and then emits `true` on the **Success** output. If no reply arrives in time or the request fails, the task emits the error on the **Error** output.

## Remarks

To answer a request inside another workflow, subscribe to the subject with the [[user-guide-automation-task-core-messagebus-listener]] task and reply with the [[user-guide-automation-task-core-messagebus-reply]] task.

Text received on `Message` together with the activation is parsed as JSON: text that is not JSON is sent as `{}`, and numeric text is sent as a number, which loses the last digits of a 19-digit MES `Id`.

A `MessageType` other than `Notification` or `Request` sends nothing and emits neither `Success` nor `Error`.