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EventBridge supports the transformation of event content. EventBridge can transform events in the standard CloudEvents format to the event type that an event target can receive before the events are routed to the event target. This topic describes the event transformation methods provided by EventBridge.

Background information

EventBridge supports the following event transformation methods:

Complete Event
Partial Event
Fixed Value
Template

Complete Event

If you specify Complete Event as the transformation method, EventBridge does not transform an event and routes the complete event in the CloudEvents format to the event target. The following table describes a sample event for which the Complete Event transformation method is used.

Note

For information about CloudEvents, see CloudEvents 1.0.

Event before transformation

Transformation method

Event after transformation

{
    "id":"7adc8c1a-645d-4476-bdef-5d6fb57f****",
    "source":"acs.oss",
    "specversion":"1.0",
    "type":"oss:ObjectCreated:PostObject",
    "datacontenttype":"application/json",
    "dataschema":"http://example.com/test.json",
    "subject":"acs:oss:cn-hangzhou:1234567:xls-papk/game_apk/123.jpg",
    "time":"2020-08-17T16:04:46.149Asia/Shanghai",
    "aliyuneventbusname":"demo-bus",
    "aliyunregionid":"Shanghai",
    "data":{
        "name":"test",
        "scope":100
    }
}

Complete Event

{
    "id":"7adc8c1a-645d-4476-bdef-5d6fb57f****",
    "source":"acs.oss",
    "specversion":"1.0",
    "type":"oss:ObjectCreated:PostObject",
    "datacontenttype":"application/json",
    "dataschema":"http://example.com/test.json",
    "subject":"acs:oss:cn-hangzhou:1234567:xls-papk/game_apk/123.jpg",
    "time":"2020-08-17T16:04:46.149Asia/Shanghai",
    "aliyuneventbusname":"demo-bus",
    "aliyunregionid":"Shanghai",
    "data":{
        "name":"test",
        "scope":100
    }
}

Partial Event

If you specify Partial Event as the transformation method, EventBridge extracts fields from an event in the CloudEvents format by using JSONPath and routes the specified content of the event to the event target. The following table describes a sample event for which the Partial Event transformation method is used.

Event before transformation

Transformation method

Event after transformation

{
    "id":"7adc8c1a-645d-4476-bdef-5d6fb57f****",
    "source":"acs.oss",
    "specversion":"1.0",
    "type":"oss:ObjectCreated:PostObject",
    "datacontenttype":"application/json",
    "dataschema":"http://example.com/test.json",
    "subject":"acs:oss:cn-hangzhou:1234567:xls-papk/game_apk/123.jpg",
    "time":"2020-08-17T16:04:46.149Asia/Shanghai",
    "aliyuneventbusname":"demo-bus",
    "aliyunregionid":"Shanghai",
    "data":{
        "name":"test",
        "scope":100
    }
}

Partial Event

$.data.name

Note

You can define only one variable if you use the Partial Event transformation method.
value: The value can be up to 10,240 characters in length.

test

Fixed Value

If you specify Fixed Value as the transformation method, an event only serves as a trigger. EventBridge routes fixed values in an event to the event target, regardless of the event content. The following table describes a sample event for which the Fixed Value transformation method is used.

Event before transformation

Transformation method

Event after transformation

{
    "id":"7adc8c1a-645d-4476-bdef-5d6fb57f****",
    "source":"acs.oss",
    "specversion":"1.0",
    "type":"oss:ObjectCreated:PostObject",
    "datacontenttype":"application/json",
    "dataschema":"http://example.com/test.json",
    "subject":"acs:oss:cn-hangzhou:1234567:xls-papk/game_apk/123.jpg",
    "time":"2020-08-17T16:04:46.149Asia/Shanghai",
    "aliyuneventbusname":"demo-bus",
    "aliyunregionid":"Shanghai",
    "data":{
        "name":"test",
        "scope":100
    }
}

Fixed Value

test1

Note

value: The value can be up to 10,240 characters in length.

test1

Template

If you specify Template as the transformation method, EventBridge extracts fields from an event in the CloudEvents format by using JSONPath, stores the values in variables, and then routes the event in the format that is defined in the template to the event target. The following table describes a sample event for which the Template transformation method is used.

Event before transformation

Transformation method

Event after transformation

{
    "id":"7adc8c1a-645d-4476-bdef-5d6fb57f****",
    "source":"acs.oss",
    "specversion":"1.0",
    "type":"oss:ObjectCreated:PostObject",
    "datacontenttype":"application/json",
    "dataschema":"http://example.com/test.json",
    "subject":"acs:oss:cn-hangzhou:1234567:xls-papk/game_apk/123.jpg",
    "time":"2020-08-17T16:04:46.149Asia/Shanghai",
    "aliyuneventbusname":"demo-bus",
    "aliyunregionid":"Shanghai",
    "data":{
        "name":"test",
        "scope":100
    }
}

Template

Variable
```
{
    "name":"$.data.name",
    "constant":"Please deal with it timely."
}
```
Note
- The value extracted by JSONPath can be a variable or a fixed value.
- Nested structures are not supported when you define variables.
- value: The value can be up to 10,240 characters in length.
Template
```
The instance is broken, which name is ${name}, ${constant}
```
Note
template: The value can be up to 10,240 characters in length.

The instance is broken, which name is test, Please deal with it timely.

You can specify a custom template in the string or JSON format, transform an event based on the template, and route the event to an event target. EventBridge supports the following types of templates:

Simple string
Simple JSON
JSON that includes parameters and fixed values

Table 1. Simple string
Event before transformation	Transformation method	Event after transformation
`{ "id":"7adc8c1a-645d-4476-bdef-5d6fb57f****", "source":"acs.oss", "specversion":"1.0", "type":"oss:ObjectCreated:PostObject", "datacontenttype":"application/json", "dataschema":"http://example.com/test.json", "subject":"acs:oss:cn-hangzhou:1234567:xls-papk/game_apk/123.jpg", "time":"2020-08-17T16:04:46.149Asia/Shanghai", "aliyuneventbusname":"demo-bus", "aliyunregionid":"Shanghai", "data":{ "name":"test", "state":"RUNNING" } }`	Template Variable `{ "name":"$.data.name", "state":"$.data.state" }` Template `"name ${name} is in ${state}"`	`"name test is in RUNNING"`

Event before transformation

Transformation method

Event after transformation

{
    "id":"7adc8c1a-645d-4476-bdef-5d6fb57f****",
    "source":"acs.oss",
    "specversion":"1.0",
    "type":"oss:ObjectCreated:PostObject",
    "datacontenttype":"application/json",
    "dataschema":"http://example.com/test.json",
    "subject":"acs:oss:cn-hangzhou:1234567:xls-papk/game_apk/123.jpg",
    "time":"2020-08-17T16:04:46.149Asia/Shanghai",
    "aliyuneventbusname":"demo-bus",
    "aliyunregionid":"Shanghai",
    "data":{
        "name":"test",
        "state":"RUNNING"
    }
}

Template

Variable

{
    "name":"$.data.name",
    "state":"$.data.state"
}

Template
```
"name ${name} is in ${state}"
```

"name test is in RUNNING"

Table 2. Simple JSON
Event before transformation	Transformation method	Event after transformation
`{ "id":"7adc8c1a-645d-4476-bdef-5d6fb57f****", "source":"acs.oss", "specversion":"1.0", "type":"oss:ObjectCreated:PostObject", "datacontenttype":"application/json", "dataschema":"http://example.com/test.json", "subject":"acs:oss:cn-hangzhou:1234567:xls-papk/game_apk/123.jpg", "time":"2020-08-17T16:04:46.149Asia/Shanghai", "aliyuneventbusname":"demo-bus", "aliyunregionid":"Shanghai", "data":{ "name":"test", "state":"RUNNING" } }`	Template Variable `{ "name":"$.data.name", "state":"$.data.state" }` Template `{ "name":"${name}", "state":"${state}" }`	`{ "name":"test", "state":"RUNNING" }`

Event before transformation

Transformation method

Event after transformation

{
    "id":"7adc8c1a-645d-4476-bdef-5d6fb57f****",
    "source":"acs.oss",
    "specversion":"1.0",
    "type":"oss:ObjectCreated:PostObject",
    "datacontenttype":"application/json",
    "dataschema":"http://example.com/test.json",
    "subject":"acs:oss:cn-hangzhou:1234567:xls-papk/game_apk/123.jpg",
    "time":"2020-08-17T16:04:46.149Asia/Shanghai",
    "aliyuneventbusname":"demo-bus",
    "aliyunregionid":"Shanghai",
    "data":{
        "name":"test",
        "state":"RUNNING"
    }
}

Template

Variable

{
    "name":"$.data.name",
    "state":"$.data.state"
}

Template

{
    "name":"${name}",
    "state":"${state}"
}

{
    "name":"test",
    "state":"RUNNING"
}

Table 3. JSON that includes variables and fixed values
Event before transformation	Transformation method	Event after transformation
`{ "id":"7adc8c1a-645d-4476-bdef-5d6fb57f****", "source":"acs.oss", "specversion":"1.0", "type":"oss:ObjectCreated:PostObject", "datacontenttype":"application/json", "dataschema":"http://example.com/test.json", "subject":"acs:oss:cn-hangzhou:1234567:xls-papk/game_apk/123.jpg", "time":"2020-08-17T16:04:46.149Asia/Shanghai", "aliyuneventbusname":"demo-bus", "aliyunregionid":"Shanghai", "data":{ "name":"test", "state":"RUNNING" } }`	Template Variable `{ "name":"$.data.name", "state":"$.data.state" }` Template `{ "name":"${name}", "state":[ 9, "${state}", true ], "Transformed":"Yes" }`	`{ "name":"test", "state":[ 9, "RUNNING", true ], "Transformed":"Yes" }`

Event before transformation

Transformation method

Event after transformation

{
    "id":"7adc8c1a-645d-4476-bdef-5d6fb57f****",
    "source":"acs.oss",
    "specversion":"1.0",
    "type":"oss:ObjectCreated:PostObject",
    "datacontenttype":"application/json",
    "dataschema":"http://example.com/test.json",
    "subject":"acs:oss:cn-hangzhou:1234567:xls-papk/game_apk/123.jpg",
    "time":"2020-08-17T16:04:46.149Asia/Shanghai",
    "aliyuneventbusname":"demo-bus",
    "aliyunregionid":"Shanghai",
    "data":{
        "name":"test",
        "state":"RUNNING"
    }
}

Template

Variable

{
    "name":"$.data.name",
    "state":"$.data.state"
}

Template

{
    "name":"${name}",
    "state":[
        9,
        "${state}",
        true
    ],
    "Transformed":"Yes"
}

{
    "name":"test",
    "state":[
        9,
        "RUNNING",
        true
    ],
    "Transformed":"Yes"
}