Simple Message Queue (formerly MNS) queue triggers

Constraints

• The Simple Message Queue (formerly MNS) queue and the Function Compute function must be in the same region.

• If your Alibaba Cloud account reaches the EventBridge event-stream limit, you cannot create additional Simple Message Queue (formerly MNS) queue triggers. For current limits, see Limits.

Prerequisites

Before you begin, ensure that you have:

• EventBridge activated and permissions granted: Activate EventBridge and grant permissions to a RAM user

• A Function Compute event function: Create an event function

• Simple Message Queue (formerly MNS) activated and RAM user access granted: Activate SMQ and authorize RAM users to access SMQ

• A queue created in Simple Message Queue (formerly MNS): Create a queue

Step 1: Create a trigger

1. Log on to the Function Compute console and click the function you want to use.

2. On the function details page, click the Configurations tab, then go to Triggers and click Create Trigger.

3. Fill in the trigger settings. The key field is Invocation Method: For details, see Synchronous invocation and Asynchronous invocation.

   Invocation method	Behavior	Max payload	When to use
   Sync Invocation	Function Compute waits for the function to return before delivering the next event or batch	32 MB	Order or sequential processing matters
   Async Invocation	Function Compute delivers the event and immediately moves to the next one; the function runs in the background	128 KB	High-throughput scenarios where you want to consume events quickly

4. Click OK.

For advanced settings such as push settings, retry policies, and dead-letter queues, see Advanced features of triggers.

After the trigger is created, it appears on the Triggers tab. To modify or delete it, see Manage triggers.

Step 2: (Optional) Configure test parameters

The function receives Simple Message Queue (formerly MNS) events as an event parameter — an array of CloudEvents-formatted objects. To test your function code without sending a real message, simulate the event manually.

1. On the Code tab, click the icon next to Test Function and select Configure Test Parameters.

2. In the Configure Test Parameters panel, click Create New Test Event or Modify Existing Test Event, enter an event name and the event content below, then click OK.

Sample event payload:

[
  {
    "id": "c2g71017-6f65-fhcf-a814-a396fc8d****",
    "source": "MNS-Function-mnstrigger",
    "specversion": "1.0",
    "type": "mns:Queue:SendMessage",
    "datacontenttype": "application/json; charset=utf-8",
    "subject": "acs:mns:cn-hangzhou:164901546557****:queues/zeus",
    "time": "2021-04-08T06:28:17.093Z",
    "aliyunaccountid": "164901546557****",
    "aliyunpublishtime": "2021-10-15T07:06:34.028Z",
    "aliyunoriginalaccountid": "164901546557****",
    "aliyuneventbusname": "MNS-Function-mnstrigger",
    "aliyunregionid": "cn-chengdu",
    "aliyunpublishaddr": "42.120.XX.XX",
    "data": {
      "requestId": "606EA3074344430D4C81****",
      "messageId": "C6DB60D1574661357FA227277445****",
      "messageBody": "TEST"
    }
  },
  {
    "id": "d2g71017-6f65-fhcf-a814-a396fc8d****",
    "source": "MNS-Function-mnstrigger",
    "specversion": "1.0",
    "type": "mns:Queue:SendMessage",
    "datacontenttype": "application/json; charset=utf-8",
    "subject": "acs:mns:cn-hangzhou:164901546557****:queues/zeus",
    "time": "2021-04-08T06:28:17.093Z",
    "aliyunaccountid": "164901546557****",
    "aliyunpublishtime": "2021-10-15T07:06:34.028Z",
    "aliyunoriginalaccountid": "164901546557****",
    "aliyuneventbusname": "MNS-Function-mnstrigger",
    "aliyunregionid": "cn-chengdu",
    "aliyunpublishaddr": "42.120.XX.XX",
    "data": {
      "requestId": "606EA3074344430D4C81****",
      "messageId": "C6DB60D1574661357FA227277445****",
      "messageBody": "TEST"
    }
  }
]

Step 3: Write and test the function

After the trigger is created, write your function code, deploy it, then verify that the trigger works end-to-end.

'use strict';
/*
To enable the initializer feature
please implement the initializer function as below:
exports.initializer = (context, callback) => {
  console.log('initializing');
  callback(null, '');
};
*/
exports.handler = (event, context, callback) => {
  console.log("event: %s", event);
  // Parse and process event.
  callback(null, 'return result');
}

Test the function

Use either method:

• Simulated event: If you configured a test event in Step 2, click Test Function on the Code tab.

• Real message: Log on to the Simple Message Queue (formerly MNS) console, select the source queue, and click Send Message.

After the function executes, view the output in Real-time Logs.

What's next

• Modify or delete a trigger: Manage triggers

• Configure retry policies and dead-letter queues: Advanced features of triggers