Overview

This document describes how to access CKafka to send/receive messages with the SDK for Node.js in a VPC.

Prerequisites

• Install GCC
• Install Node.js
• Download the demo

Directions

Preparations

1. Upload the nodejskafkademo in the downloaded demo to the Linux server.
2. Log in to the Linux server and enter the nodejskafkademo directory.

Step 1. Install the C++ dependency library

1. Run the following command to switch to the yum source configuration directory /etc/yum.repos.d/.

   cd /etc/yum.repos.d/
   

2. Create the yum source configuration file confluent.repo.

   [Confluent.dist]
   name=Confluent repository (dist)
   baseurl=https://packages.confluent.io/rpm/5.1/7
   gpgcheck=1
   gpgkey=https://packages.confluent.io/rpm/5.1/archive.key
   enabled=1   
   [Confluent]
   name=Confluent repository
   baseurl=https://packages.confluent.io/rpm/5.1
   gpgcheck=1
   gpgkey=https://packages.confluent.io/rpm/5.1/archive.key
   enabled=1
   

3. Run the following command to install the C++ dependency library.

   yum install librdkafka-devel
   

Step 2. Install the Node.js dependency library

1. Run the following command to specify the OpenSSL header file path for the preprocessor.

   export CPPFLAGS=-I/usr/local/opt/openssl/include
   

2. Run the following command to specify the OpenSSL library path for the connector.

   export LDFLAGS=-L/usr/local/opt/openssl/lib
   

3. Run the following command to install the Node.js dependency library.

   npm install i --unsafe-perm node-rdkafka
   

Step 3. Prepare the configurations

Create the CKafka configuration file setting.js.

module.exports = {
  'bootstrap_servers': ["xxx.ckafka.tencentcloudmq.com:6018"],
  'topic_name': 'xxx',
  'group_id': 'xxx'
}

Parameter	Description
bootstrap_servers	Accessed network, which can be copied from the Network column in the Access Mode section on the Instance Details page in the console.
topic_name	Topic name, which can be copied from the Topic Management page in the console.
group_id	You can customize it. After the demo runs successfully, you can see the consumer on the Consumer Group page.

Step 4. Send a message

1. Write the message production program producer.js.

   const Kafka = require('node-rdkafka');
     const config = require('./setting');
     console.log("features:" + Kafka.features);
     console.log(Kafka.librdkafkaVersion);
   
     var producer = new Kafka.Producer({
         'api.version.request': 'true',
         // To set the entry service, please get the corresponding service address in the console
         'bootstrap.servers': config['bootstrap_servers'],
         'dr_cb': true,
         'dr_msg_cb': true,
   
         // Number of retries upon request error. We recommend you set the value to be greater than 0. Retries can ensure as much as possible that the message will not be lost
         'retries': '0',
         // The time between when a request fails and the next time the request is retried
         "retry.backoff.ms": 100,
         // Timeout period of the producer network request
         'socket.timeout.ms': 6000,
     });
   
     var connected = false
   
     producer.setPollInterval(100);
   
     producer.connect();
   
     producer.on('ready', function() {
     connected = true
     console.log("connect ok")
     });
   
     producer.on("disconnected", function() {
     connected = false;
     producer.connect();
     })
   
     producer.on('event.log', function(event) {
         console.log("event.log", event);
     });
   
     producer.on("error", function(error) {
         console.log("error:" + error);
     });
   
     function produce() {
         try {
             producer.produce(
             config['topic_name'],   
             null,      
             new Buffer('Hello CKafka Default'),      
             null,   
             Date.now()
             );
         } catch (err) {
             console.error('Error occurred when sending message(s)');
             console.error(err);
         }
   
     }
   
     producer.on('delivery-report', function(err, report) {
         console.log("delivery-report: producer ok");
     });
   
     producer.on('event.error', function(err) {
         console.error('event.error:' + err);
     })
   
     setInterval(produce, 1000, "Interval");
   

2. Run the following command to send the message.

   node producer.js
   

3. View the operation result.
   

4. On the Topic Management page in the CKafka console, select the corresponding topic and click More > Message Query to view the just sent message.
   

Step 5. Subscribe to a message

1. Create the message consumer program consumer.js.

   const Kafka = require('node-rdkafka');
     const config = require('./setting');
     console.log(Kafka.features);
     console.log(Kafka.librdkafkaVersion);
     console.log(config)
   
     var consumer = new Kafka.KafkaConsumer({
         'api.version.request': 'true',
         // To set the entry service, please get the corresponding service address in the console
         'bootstrap.servers': config['bootstrap_servers'],
         'group.id' : config['group_id'],
   
         // Consumer timeout period when the Kafka consumer grouping mechanism is used. If the broker does not receive the heartbeat of the consumer within this period,
         // the consumer will be considered to have failed and the broker will initiate rebalance
         'session.timeout.ms': 10000,
         // Client request timeout period. If no response is received after this time elapses, the request will time out and fail
         'metadata.request.timeout.ms': 305000,
         // Set the internal retry interval of the client
         'reconnect.backoff.max.ms': 3000
   
     });
   
     consumer.connect();
   
     consumer.on('ready', function() {
     console.log("connect ok");
     consumer.subscribe([config['topic_name']]);
     consumer.consume();
     })
   
     consumer.on('data', function(data) {
     console.log(data);
     });
   
     consumer.on('event.log', function(event) {
         console.log("event.log", event);
     });
   
     consumer.on('error', function(error) {
         console.log("error:" + error);
     });
   
     consumer.on('event', function(event) {
             console.log("event:" + event);
     });
   

2. Run the following command to consume the message.

   node consumer.js
   

3. View the operation result.
   

4. On the Consumer Group page in the CKafka console, select the corresponding consumer group, enter the topic name in Topic Name, and click Query Details to view the consumption details.