Using the MQTT client utility
Use one or more MQTT client utilities to test your telemetry setup. Within the scope of this task, one client utility is used to publish and subscribe to messages.
Before you begin
- Make sure that the telemetry (MQXR) service is running.
- You need at least one running telemetry channel to successfully use the MQTT client utility.
About this task
PlainText
telemetry
channel created with the Define sample configuration wizard.By
default, the MCA user ID of the PlainText
channel
is set to guest
on Windows,
and nobody
on Linux®.
You need these default values in order to subscribe to topics.
Procedure
- Right-click the
PlainText
telemetry channel, then click Run MQTT Client Utility. The client utility window opens. The Host and Port fields are automatically set using values from the selected telemetry channel. - Type a client ID in the Client identifier field. A new client identifier is generated each time you launch an MQTT client utility from a telemetry channel. You can either use the generated identifier or type a name of your choice. If you run more than one client utility on a telemetry channel, ensure that you use different client IDs for each client utility. If two MQTT client utilities have the same client ID, the most recent one to connect forcefully disconnects the previous one. When you run more than one MQTT client utility from a telemetry channel, the generated client identifier has a numeric suffix that is incremented every time a new client utility is started.
- Click Options to open the Connection Options window. You can start the client utility with a clean session, or configure the last will and testament options.
- Click Connect to establish a connection
with the
PlainText
telemetry channel. A new event entry ofConnected
is displayed in the Client history. - Type a topic name in the Subscription Topic field.
The default topic name is
testTopic
and this name is used throughout this task. - Select the subscription quality of service from the Request QoS menu.
- Click Subscribe to subscribe to
the topic
testTopic
. A new event entry ofSubscribed
is displayed in the Client history, along with the topic name, QoS, and the time of subscription. - Accept the default topic name,
testTopic
, in the Publication Topic field. In general, ensure that the subscription and publication topics match so that the MQTT client receives messages from the correct topic. - Type a message in the Message field.
The default message test is
Test Message
. - Select the publication quality of service from the Request QoS menu.
- Select Retained to forward the most recent retained publication on this topic to new subscribers.
- Click Publish to publish the message
on the
testTopic
topic for interested subscribers. A new event entry ofPublished
is displayed in the Client history, along with the topic name, QoS, whether the message is retained, and the time of subscription. On the receiving client utility, a new event entry ofReceived
is displayed in the Client history. - Select the received message in the Client history, then click View message to view the full message in the Message Viewer window. Alternatively, select the message and press Enter, or double-click the received message.
Results
Publishing messages and viewing the messages from topics subscribed to, shows that you have correctly set up your queue manager for Telemetry.