Help Center/ IoT Device Access/ Getting Started/ Quick Device Access - Message Sending and Receiving/ Using MQTT.fx to Send and Receive Messages
Updated on 2026-09-30 GMT+08:00
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Using MQTT.fx to Send and Receive Messages

Overview

MQTT.fx is an MQTT client written in Java based on Eclipse Paho. It supports Windows, macOS, and Linux OSs. It can be used to simulate the connection of devices to IoTDA through MQTTS/MQTT, and the publishing and subscription of messages through topics. This section uses Windows as an example to describe how to use MQTT.fx to access IoTDA and send and receive messages.

Figure 1 Message exchange process between MQTT.fx and IoTDA

Prerequisites

  • You have registered a Huawei Cloud account in this page.

Using MQTT.fx to Connect to IoTDA

  1. Download MQTT.fx (64-bit OS) or MQTT.fx (32-bit OS) and install it.
  2. Open the MQTT.fx client and choose Extras > Edit Connection Profiles from the menu bar.
  3. On the Edit Connection Profiles page, set related parameters and click OK.
    Figure 2 MQTT.fx connection parameters

    Parameter

    Description

    Example Value

    Profile Name

    Name of the configuration file.

    Enter MQTT Test.

    Profile Type

    Type of the connection to be configured.

    The value is fixed at MQTT Broker, indicating that the MQTT server is to be connected.

    Broker Address

    Access address of the MQTT server.

    Access your instance, choose Overview, click Access Details, and obtain the MQTTS access address. For details, see Obtaining Resources.

    Broker Port

    Access port of the MQTT server.

    Enter 8883.

    Client ID

    IoTDA can send and receive messages only after device access authentication is successful. For details about device authentication parameters, see

    MQTT Device Connection Authentication.

    Go to the device details page, find MQTT Connection Parameter, and click View to check the client ID, username, and password.

    User Name

    Password

    SSL/TLS

    Enable SSL/TLS

    Whether to use the SSL or TLS encryption protocol.

    Yes

    Protocol

    Protocol version.

    Select TLSv1.2.

    CA certificate file

    CA certificate file.

    Obtain the CA certificate of the corresponding region by referring to Certificates.
  4. After setting the parameters, click Connect. If the icon in the upper right corner turns green, MQTT.fx has been connected to IoTDA. If the icon in the upper right corner turns red, the connection fails. Click the Log tab to check logs, modify the configuration based on the log information, and try again.
    Figure 3 MQTT.fx connection
  1. Access IoT Device Access and click Access Console. Click the target instance card.
  2. In the navigation pane, choose Devices > All Devices to check the device status. The device status is expected to be online.
    Figure 4 Device list - Device online status

Using MQTT.fx to Send Messages

  1. Click the Publish tab on the MQTT.fx client.
  2. On the displayed tab page, enter the topic name in the Topic text box on the left, for example, /test/deviceToCloud. Enter the message content in the Message text box, for example, hello. Click Publish to send the message.
    Figure 5 MQTT.fx message sending
  3. Access IoT Device Access and click Access Console. Click the target instance card.
  4. In the navigation pane, choose Devices > All Devices. On the displayed page, click View. On the Message Trace tab page, check the messages sent by MQTT.fx.
    Figure 6 Message tracing - Viewing results
  1. After MQTT.fx sends messages to the platform, configure data forwarding rules (see Data Forwarding Process) to forward the messages to message middleware, storage, data analysis, or service applications.

Using MQTT.fx to Receive Messages

  1. Click the Subscribe tab on the MQTT.fx client.
  2. On the displayed tab page, enter the topic name in the Topic text box on the left and click Subscribe. /test/cloudToDevice is used as an example. After the topic is subscribed to, check the topic in the subscription list.
    Figure 7 MQTT.fx subscription topic
  3. Access IoT Device Access and click Access Console. Click the target instance card.
  4. In the navigation pane, choose Devices > All Devices. On the device list, click a device to access its details page.
  5. Click the Cloud Delivery tab. On the Message Delivery tab page, click Deliver Message. In the displayed dialog box, configure the content and the parameters for the message to deliver.
    Figure 8 Delivering a message - Custom topic
  6. On the MQTT.fx client, click the Subscribe tab. The message received from the subscribed topic is displayed.
    Figure 9 Checking messages using MQTT.fx