This article describes how to edit the topic category of a product. Each topic category of a product is used by all devices of the product.

Procedure

  1. Log on to the IoT Platform console.
  2. In the left-side navigation pane, choose Devices > Products.
  3. On the Products page, find the product for which you want to edit a topic category, and click View.
  4. On the Product Details page, choose Topic Categories > Topic Category > Edit Topic Category.
  5. Set the required parameters, and click OK.
    Edit a topic category
    Parameter Description
    Device Operation Authorizations The permission of the device for the topic category. Valid values: Publish, Subscribe, and Publish and Subscribe.
    Topic Category The name of the topic category. The name can contain letters, digits, and underscores (_). Each field of the topic category cannot be empty.
    Note If you set the Device Operation Authorizations parameter of a topic category to Subscribe, you can specify the + and # wildcards in the topic category. These wildcards allow devices to subscribe to multiple topics at a time. For more information about how to use wildcards, see A topic that includes one or more wildcards.
    Description The description.

A topic that includes one or more wildcards

If you set the Device Operation Authorizations parameter to Subscribe, IoT Platform allows you to specify two wildcards in a topic. This feature allows a device to subscribe to multiple topics at a time.

Wildcard Description
# This wildcard must be specified for the last field in a topic and can match all field values at the current level and sub-levels.

For example, you create the /a1aycMA****/${deviceName}/user/# topic category. If Device 1 subscribes to the /a1aycMA****/device1/user/# topic, the device subscribes to all topics that start with /a1aycMA****/device1/user/, for example, /a1aycMA****/device1/user/update and /a1aycMA****/device1/user/update/error.

+ This wildcard can match all field values at the current level.

For example, you create the /a1aycMA****/${deviceName}/user/+/error topic category. If Device 1 subscribes to the /a1aycMA****/device1/user/+/error topic, the device subscribes to multiple topics, such as /a1aycMA****/device1/user/get/error and /a1aycMA****/device1/user/update/error.

A topic that includes one or more wildcards represents a set of topics. A device can subscribe to the topic. However, on the Topic List page of the device, the Post Message action is unavailable for the topic. You cannot send messages to the device by using the topic.

Topic-based communication

IoT Platform calls the Pub API operation to publish messages to a specified topic. Devices receive messages from IoT Platform by subscribing to the topic.

For more information about topic-based communication, see Use custom topics for communication.