RocketMQ triggers

How it works

After you submit a trigger creation request in the Function Compute console, Function Compute automatically creates an Event stream resource in EventBridge based on the trigger configuration.

After the trigger is created, you can view the trigger information in the Function Compute console and view the automatically created resources in the EventBridge console. When a message is enqueued in the source ApsaraMQ for RocketMQ instance, Function Compute is invoked. During each invocation, one or more message events are pushed to the function as a batch based on your batching configuration. This behavior suits end-to-end streaming data processing scenarios.

Usage notes

• The ApsaraMQ for RocketMQ instance that serves as the event source must reside in the same region as the Function Compute function.

• If the number of created event streams exceeds the upper limit, you can no longer create RocketMQ triggers.

For the limits on the number of resources involved in creating a trigger within a single Alibaba Cloud account in a single region, see Limits.

Prerequisites

• EventBridge

  • Activate EventBridge and grant permissions to a RAM user

• Function Compute

  • Create an event function

• ApsaraMQ for RocketMQ

  • Activate and grant permissions on ApsaraMQ for RocketMQ

  • Create an instance, a topic, and a group ID

Step 1: Create a trigger

1. Log on to the Function Compute console, find the function that you want to manage, and then on the function details page, click the Trigger tab and click Create Trigger.

2. In the Create Trigger panel, set Trigger Type to ApsaraMQ for RocketMQ, configure the parameters described in the following table, and then click OK.

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

Step 2: (Optional) Configure function entry parameters

The ApsaraMQ for RocketMQ event source is passed to the function as an event input parameter. Use your code to parse the event parameter and process it. You can pass an event to the function manually to simulate a trigger event and check whether the function code is correct.

1. On the Code tab of the function details page, click the icon next to Test Function and select Configure Test Parameters from the drop-down list.

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

The event format is as follows.

[
    {
    "id":"94ebc15f-f0db-4bbe-acce-56fb72fb****",
    "source":"RocketMQ-Function-rocketmq-trigger",
    "specversion":"1.0",
    "type":"mq:Topic:SendMessage",
    "datacontenttype":"application/json; charset=utf-8",
    "subject":"acs:mq:cn-hangzhou:164901546557****:MQ_INST_164901546557****_BXhFHryi%TopicName",
    "time":"2021-04-08T06:01:20.766Z",
    "aliyunaccountid":"164901546557****",
    "aliyunpublishtime":"2021-10-15T02:05:16.791Z",
    "aliyunoriginalaccountid":"164901546557****",
    "aliyuneventbusname":"RocketMQ-Function-rocketmq-trigger",
    "aliyunregionid":"cn-chengdu",
    "aliyunpublishaddr":"42.120.XX.XX",
    "data":{
        "topic":"TopicName",
        "systemProperties":{
            "MIN_OFFSET":"0",
            "TRACE_ON":"true",
            "MAX_OFFSET":"8",
            "MSG_REGION":"cn-hangzhou",
            "KEYS":"systemProperties.KEYS",
            "CONSUME_START_TIME":1628577790396,
            "TAGS":"systemProperties.TAGS",
            "INSTANCE_ID":"MQ_INST_164901546557****_BXhFHryi"
        },
        "userProperties":{

        },
        "body":"TEST"
    }
    },
    {
    "id":"94ebc15f-f0db-4bbe-acce-56fb72fb****",
    "source":"RocketMQ-Function-rocketmq-trigger",
    "specversion":"1.0",
    "type":"mq:Topic:SendMessage",
    "datacontenttype":"application/json; charset=utf-8",
    "subject":"acs:mq:cn-hangzhou:164901546557****:MQ_INST_164901546557****_BXhFHryi%TopicName",
    "time":"2021-04-08T06:01:20.766Z",
    "aliyunaccountid":"164901546557****",
    "aliyunpublishtime":"2021-10-15T02:05:16.791Z",
    "aliyunoriginalaccountid":"164901546557****",
    "aliyuneventbusname":"RocketMQ-Function-rocketmq-trigger",
    "aliyunregionid":"cn-chengdu",
    "aliyunpublishaddr":"42.120.XX.XX",
    "data":{
        "topic":"TopicName",
        "systemProperties":{
            "MIN_OFFSET":"0",
            "TRACE_ON":"true",
            "MAX_OFFSET":"8",
            "MSG_REGION":"cn-hangzhou",
            "KEYS":"systemProperties.KEYS",
            "CONSUME_START_TIME":1628577790396,
            "TAGS":"systemProperties.TAGS",
            "INSTANCE_ID":"MQ_INST_164901546557****_BXhFHryi"
        },
        "userProperties":{

        },
        "body":"TEST"
    }
    }
]

The following table describes the parameters contained in the data field. For the parameters defined in the CloudEvents specification, see Overview.

Step 3: Write and test the function code

After you create the trigger, write and test the function code to verify that the code is correct. In practice, when an ApsaraMQ for RocketMQ event is delivered to Function Compute through EventBridge, the trigger automatically invokes the function.

1. On the Code tab of the function details page, write your code in the code editor, and then click Deploy.

   This topic uses Node.js function code as an example.

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

2. Test the function.

   Method 1: If you configured the event function entry parameter to simulate the event source, click Test Function.

   Method 2: Log on to the ApsaraMQ for RocketMQ console, find the topic of the ApsaraMQ for RocketMQ instance that you want to use, click Message Send/Receive Test, and then send a message as prompted.

3. After the run is complete, on the Code tab of the function details page, click Real-time Logs to view the result.