MQTT Client

the mqtt client is a built in client for the message broker in litmus unify you subscribe to topics, watch messages arrive, and publish test messages without installing a separate mqtt tool use mqtt client to confirm that a broker is receiving messages when a device is not reporting, subscribing here tells you whether the data reaches the broker at all, which separates a device problem from a downstream one when you set up a topic, publishing a test message confirms the path first access mqtt client ui to access the mqtt client pane navigate to mqtt client interface element description connection status whether the client is connected to the broker nothing arrives in the feed and nothing can be published while it reads disconnected add subscription subscribes to a topic wildcards are supported, so + matches one topic level and # matches all remaining levels filter narrows what the feed displays by topic or content it filters the view only and does not change what you are subscribed to auto scroll keeps the newest message in view turn it off to read one message on a busy topic message feed messages arriving on your subscribed topics in ascending order publish message panel sends a message to a topic see field description in publish message fields publish message fields field description topic topic to publish to message payload to send retain tells the broker to keep this message and publish it to new subscribing clients qos delivery guarantee 0 at most once, 1 at least once, 2 exactly once send publishes the message troubleshooting symptom what to check no messages arrive confirm that the subscription topic path matches the publisher's topic and check if wildcard usage is appropriate a message will not publish validate that the topic and message payload format are correct considerations the feed starts empty and fills as messages arrive it is not a history, so subscribing after an event does not show past messages retain has a lasting effect that the other fields do not a retained test message stays on the topic and is delivered to every later subscriber until something overwrites it