Use an event bus as the event source for an event stream-EventBridge(EventBridge)-阿里云帮助中心

An event bus collects events from multiple sources and routes them to targets based on rules. When you need to filter, transform, or deliver events from a bus through a lightweight pipeline instead of full event rules, configure the event bus as the source of an event stream. The event stream forwards matched events for processing and delivery to a downstream target.

The default event bus automatically receives events from Alibaba Cloud services. Use a custom event bus if your events come from a custom application.

Prerequisites

Before you begin, make sure that you have:

Activated EventBridge and granted the required permissions

Create the event stream

Log on to the EventBridge console. In the left-side navigation pane, click Event Streams.
In the top navigation bar, select a region and click Create Event Stream.
In the top navigation bar, select a region and click Create Event Stream.

In the Create Event Stream panel, enter a Task Name and Description, then complete the following configuration sections.

Configure the event source

In the Source configuration wizard, set Data Provider to Event Bus and configure the following parameters.

Parameter	Description	Example
Region	Select the destination region.	China (Hangzhou)
Name	Select the destination event bus. Select `default` for Alibaba Cloud service events, or select a custom event bus for application events.	default
Subscription Rule	How the event stream subscribes to the bus. Quickly Create Rule (recommended) auto-generates a rule named `EVENTSTREAMING_xxxx`. Use Existing Rule lets you select a rule you already created.	Quickly Create Rule
Messages	Maximum number of messages that can be sent in a batch for a function call. A request is sent only when the number of backlogged messages reaches the specified value. Valid values: 1 to 10,000.	100
Interval (Unit: Seconds)	The interval at which the function is called. The system aggregates messages and sends them to Function Compute at the specified interval. Valid values: 0 to 15. Set to `0` for immediate delivery with no waiting.	3

Click Next Step.
In the Filtering, Transformation, and Sink steps, configure the event filtering and transformation rules and the event target.

Configure retry and dead-letter policies
Set the retry policy and dead-letter queue for the event stream. These policies control how EventBridge handles delivery failures.

Click Save.

Event example

Events delivered through the bus follow the CloudEvents specification. A typical event looks like this:

{
    "id": "ae3gchfi-4b4d-927d-fbj9-516ib2******",
    "type": "ui:Created:PostObject",
    "dataschema": "http://taobao.com/item.json",
    "subject": "my:subject",
    "data": {
        "name": "Eventbridge",
        "number": 100
    }
}

The top-level fields (id, type, dataschema, subject) are standard CloudEvents attributes. For definitions, see Event overview.

The data field carries the event payload. Its contents depend on the event source:

Parameter	Type	Example	Description
name	String	Eventbridge	Identifier for business logic, such as a module name or event source label.
number	Number	100	Numeric value associated with the event, such as a count, version number, or status code.

What's next

Configure retry and dead-letter policies to handle delivery failures.