ApsaraMQ for RocketMQ:Envie e receba mensagens agendadas e com atraso

Informações básicas

• As mensagens com atraso são aquelas que os brokers do ApsaraMQ for RocketMQ entregam aos consumidores após um período específico.

• As mensagens agendadas são aquelas que os brokers do ApsaraMQ for RocketMQ entregam aos consumidores em um momento específico.

A configuração de código para mensagens agendadas é igual à de mensagens com atraso via HTTP. O broker entrega ambos os tipos de mensagem aos consumidores após um período determinado, com base nos atributos das mensagens.

Para mais informações, consulte Scheduled messages and delayed messages.

Pré-requisitos

Antes de começar, conclua as seguintes etapas:

• Instale o SDK para Node.js. Para mais informações, consulte Set up the Node.js environment.

• Crie os recursos no console do ApsaraMQ for RocketMQ e especifique esses recursos no código. Esses recursos incluem instâncias, tópicos e grupos de consumidores. Para mais informações, consulte Create resources.

• Obtenha o par de AccessKey da sua conta Alibaba Cloud. Para mais informações, consulte Create an AccessKey.

Envie mensagens agendadas e com atraso

O código de exemplo a seguir demonstra como enviar mensagens agendadas e com atraso usando o SDK de cliente HTTP para Node.js:

const {
  MQClient,
  MessageProperties
} = require('@aliyunmq/mq-http-sdk');

// The HTTP endpoint. You can obtain the endpoint in the HTTP Endpoint section of the Instance Details page in the ApsaraMQ for RocketMQ console. 
const endpoint = "${HTTP_ENDPOINT}";
// Make sure that the environment variables ALIBABA_CLOUD_ACCESS_KEY_ID and ALIBABA_CLOUD_ACCESS_KEY_SECRET are configured. 
// The AccessKey ID that is used for authentication. 
const accessKeyId = process.env['ALIBABA_CLOUD_ACCESS_KEY_ID'];
// The AccessKey secret that is used for authentication. 
const accessKeySecret = process.env['ALIBABA_CLOUD_ACCESS_KEY_SECRET'];// The AccessKey ID that is used for authentication. 
const accessKeyId = "${ACCESS_KEY}";
// The AccessKey secret that is used for authentication. 
const accessKeySecret = "${SECRET_KEY}";

var client = new MQClient(endpoint, accessKeyId, accessKeySecret);

// The topic in which the message is produced. You must create the topic in the ApsaraMQ for RocketMQ console. 
const topic = "${TOPIC}";
// The ID of the instance to which the topic belongs. You must create the instance in the ApsaraMQ for RocketMQ console. 
// If the instance has a namespace, specify the ID of the instance. If the instance does not have a namespace, set the instanceId parameter to null or an empty string. You can obtain the namespace of the instance on the Instance Details page in the ApsaraMQ for RocketMQ console. 
const instanceId = "${INSTANCE_ID}";

const producer = client.getProducer(instanceId, topic);

(async function(){
  try {
    // Cyclically send four messages. 
    for(var i = 0; i < 4; i++) {
      let res;
      msgProps = new MessageProperties();
      // The custom attributes of the message. 
      msgProps.putProperty("a", i);
      // The message key. 
      msgProps.messageKey("MessageKey");
      // The period of time after which the broker delivers the message to the consumer. In this example, the broker delivers the message to the consumer after a delay of 10 seconds. Set this parameter to a timestamp in milliseconds. 
      // If you want to send a scheduled message, set the parameter to the time difference between the scheduled point in time and the current point in time. 
      msgProps.startDeliverTime(Date.now() + 10 * 1000);
      // The body and tag of the message. 
      res = await producer.publishMessage("hello mq. timer msg!", "TagA", msgProps);
      console.log("Publish message: MessageID:%s,BodyMD5:%s", res.body.MessageId, res.body.MessageBodyMD5);
    }

  } catch(e) {
    // Specify the logic that you want to use to resend or persist the message if the message fails to be sent and needs to be sent again. 
    console.log(e)
  }
})();

Assine mensagens agendadas e com atraso

O código de exemplo a seguir demonstra como assinar mensagens agendadas e com atraso usando o SDK de cliente HTTP para Node.js:

   const {
     MQClient
   } = require('@aliyunmq/mq-http-sdk');

   // HTTP endpoint of your ApsaraMQ for RocketMQ instance.
   const endpoint = "<http-endpoint>";
   // Read credentials from environment variables.
   const accessKeyId = process.env['ALIBABA_CLOUD_ACCESS_KEY_ID'];
   const accessKeySecret = process.env['ALIBABA_CLOUD_ACCESS_KEY_SECRET'];

   const client = new MQClient(endpoint, accessKeyId, accessKeySecret);

   // Topic to consume from.
   const topic = "<topic>";
   // Consumer group ID. Create this in the console first.
   const groupId = "<group-id>";
   // Instance ID. Set to null or "" if the instance has no namespace.
   const instanceId = "<instance-id>";

   const consumer = client.getConsumer(instanceId, topic, groupId);

   (async function () {
     while (true) {
       try {
         // consumeMessage(batchSize, pollingSeconds)
         //   batchSize:      max messages per request (1-16)
         //   pollingSeconds: long-polling timeout in seconds (max 30)
         const res = await consumer.consumeMessage(3, 3);

         if (res.code === 200) {
           console.log("Consume messages, requestId: %s", res.requestId);

           const handles = res.body.map((message) => {
             console.log(
               "\tMessageId:%s, Tag:%s, PublishTime:%d, NextConsumeTime:%d, " +
               "FirstConsumeTime:%d, ConsumedTimes:%d, Body:%s, Props:%j, MessageKey:%s, Prop-A:%s",
               message.MessageId,
               message.MessageTag,
               message.PublishTime,
               message.NextConsumeTime,
               message.FirstConsumeTime,
               message.ConsumedTimes,
               message.MessageBody,
               message.Properties,
               message.MessageKey,
               message.Properties.a
             );
             return message.ReceiptHandle;
           });

           // Acknowledge consumed messages. If the broker does not receive
           // an ACK before NextConsumeTime, the message is delivered again.
           const ackRes = await consumer.ackMessage(handles);
           if (ackRes.code !== 204) {
             // If the handle of the message times out, the broker fails to receive an ACK.
             console.log("Ack failed:");
             const failHandles = ackRes.body.map((error) => {
               console.log(
                 "\tErrorHandle:%s, Code:%s, Reason:%s",
                 error.ReceiptHandle, error.ErrorCode, error.ErrorMessage
               );
               return error.ReceiptHandle;
             });
             handles.forEach((handle) => {
               if (failHandles.indexOf(handle) < 0) {
                 console.log("\tSucHandle:%s", handle);
               }
             });
           } else {
             console.log("Ack succeeded, requestId: %s\n\t", ackRes.requestId, handles.join(','));
           }
         }
       } catch (e) {
         if (e.Code && e.Code.indexOf("MessageNotExist") > -1) {
           // No messages available -- long polling continues on next iteration.
           console.log("No new messages. requestId: %s, Code: %s", e.RequestId, e.Code);
         } else {
           console.log(e);
         }
       }
     }
   })();