Broadcast Communication Overview

Introduction

Broadcast communication is often used for one-to-many message communication. If multiple devices subscribe to the same broadcast topic, applications can call the broadcast message delivery API to publish messages to these devices when they are online. You can use broadcast to send notifications to devices of specific types.

For example, the Earthquake Administration sends earthquake warning information to all citizens in a specified area.

Figure 1 Example broadcast communication scenario

Scenarios

• Broadcast messages are sent to devices in a specified group.
• Broadcast messages are sent to all online devices in a specified area for earthquake warning.

Constraints

• The prefix of a broadcast topic subscribed by devices must be $oc/broadcast/.
• The length of a broadcast topic subscribed by devices cannot exceed 128 bytes.
• A maximum of seven slashes (/) can be used in a broadcast topic subscribed by devices.
• A single device can subscribe to a maximum of 50 broadcast topics.
• A topic can be subscribed to by a maximum of 1000 devices.
• The broadcast communication API on the application side can be called only once per minute.
• Currently, this function is available for standard instances in the CN North-Beijing4 region.