Configuring Asynchronous Execution Notification

Overview

Functions can be invoked synchronously or asynchronously. In asynchronous mode, FunctionGraph sends a response immediately after persisting a request. The request result cannot be known in real time. To retry when an asynchronous request fails or obtain asynchronous processing results, configure asynchronous settings.

Applications Scenarios

Retry: By default, FunctionGraph does not retry if a function fails due to a code error. If your function needs retry, for example, if third-party services often fail to be invoked, configure retry to improve the success rate.
Result notifications: FunctionGraph automatically notifies downstream services of the asynchronous execution result of a function for further processing. For example, storing execution failure information in OBS for cause analysis, or pushing execution success information to DIS or triggering the function again.

Note

Set an agency that allows FunctionGraph to access the target service.
To avoid cyclic invocation, do not set two functions as asynchronous execution targets of each other.

Procedure

Log in to the FunctionGraph console, and choose Functions > Function List in the navigation pane.
Click the name of the created function.
Choose Configuration > Configure Async Notification. On the displayed page, click Edit next to Asynchronous Notification Policy.
Figure 1 Configuring an asynchronous notification policy

Set parameters by referring to Table 1. For example, specify FunctionGraph for Target Service, as shown in the following figure.

Figure 2 Setting parameters

Table 1 Parameter description
Parameter	Description
Asynchronous Notification Policy	Max. Retries: maximum number of retries when asynchronous invocation fails. Value range: 0–3. Default value: 1. Max. Validity Period (s): maximum lifetime of a message in seconds. Value range: 1–86,400.
Success Notification	Target Service: to which a notification will be sent if a function is executed successfully. FunctionGraph OBS
Failure Notification	Target Service: to which a notification will be sent if a function fails to be executed. FunctionGraph OBS

Click OK to complete the configuration.

Configuration Description

For details about how to set the target for asynchronous invocation, see Table 2. The following shows an example:

{
        "timestamp": "2020-08-20T12:00:00.000Z",
	"request_context": {
	        "request_id": "1167bf8c-87b0-43ab-8f5f-26b16c64f252",
	        "function_urn": "urn:fss:xx-xxxx-x:xxxxxxx:function:xxxx:xxxx:latest",
	        "condition": "",
	        "approximate_invoke_count": 0
	 },
	    "request_payload": "",
	    "response_context": {
	        "status_code": 200,
	        "function_error": ""
	  },
	 "response_payload": "hello world!"
}

Table 2 Parameter description
Parameter	Description
timestamp	Time when the invocation starts.
request_context	Request context.
request_context.request_id	ID of an asynchronous invocation request.
request_context. function_urn	URN of the function that is to be executed asynchronously.
request_context.condition	Invocation error type.
request_context. approximate_invoke_count	Number of asynchronous invocation times. If the value is greater than 1, function execution has been retried.
request_payload	Original request payload.
response_context	Response context.
response_context.statusCode	Code returned after function invocation. If the code is not 200, a system error occurred.
response_context.function_error	Invocation error information.
response_payload	Payload returned after function execution.

Parent topic: Getting Started

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Creating and Initializing a Function

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Configuring VPC Access

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