订阅MQTT使用node-red在bluemix中不起作用

Question

I am having trouble in MQTT communication. I am new to MQTT and IOT. I am using IBM Bluemix as a cloud service. I can publish the data using node-red MQTT node on the device type. But I am not able to subscribe to that device and topic. Whenever I try to subscribe, it gets disconnected. Thanks

In this picture, I am publishing the status event to the device

In this picture, I am getting the published data in the cloud

However, as shown below, when i try to subscribe, it gets disconnected

PS: I am using the same client ID. I don't know how to use a different client ID for the same device type.

Answer 1

When you publish, you are publishing as a device and connecting with the device client ID. A device can not subscribe to a status event, so you should be subscribing as an application. It will connect with an ID such as A:orgId:appId https://console.ng.bluemix.net/docs/services/IoT/applications/mqtt.html#mqtt

Answer 2

I am adding this info as answer because it was too long to put as comment. You generate the API key from your Watson IOT Platform service dashboard.

When connecting an Application you need 3 properties:

Organization ($org)

API Key ($key)

API Token ($token)

Applications require an API Key to connect into an Organization. When an API Key is registered a token will be generated that must be used with that API key.

To generate your API Key and token, launch your Watson IoT service dashboard. Select “Apps” from the left sidebar, then “API Keys” in the top menu, and choose “Generate API Key” Button on top right. The platform will provide you with a pair of “API Key” and “Authentication Token”, that you need to note down.
See screenshot.

The API key will look something like this: a:$org:a84ps90Ajs

The token will look something like this: MP$08VKz!8rXwnR-Q*

When making an MQTT connection using an API key the following applies:

MQTT client ID: a:$org:$appId MQTT username must be the API key: a:$org:a84ps90Ajs MQTT password must be the authentication token: MP$08VKz!8rXwnR-Q*