sqs-consumer

What is sqs-consumer?

The sqs-consumer npm package is a simple to use library for building Amazon Simple Queue Service (SQS) based applications. It allows you to create consumers that process messages from SQS queues with ease, handling message polling, error handling, and visibility timeout extensions.

What are sqs-consumer's main functionalities?

Creating a Consumer

This code sample demonstrates how to create a basic consumer that reads messages from an SQS queue and logs the message body to the console.

const { Consumer } = require('sqs-consumer');
const AWS = require('aws-sdk');

const app = Consumer.create({
  queueUrl: 'https://sqs.us-east-1.amazonaws.com/account-id/queue-name',
  handleMessage: async (message) => {
    console.log(message.Body);
  },
  sqs: new AWS.SQS()
});

app.on('error', (err) => {
  console.error(err.message);
});

app.start();

Error Handling

This code sample shows how to handle errors that occur during message processing. The 'error' event is emitted for general errors, while the 'processing_error' event is specifically for errors that occur during message handling.

const { Consumer } = require('sqs-consumer');
const AWS = require('aws-sdk');

const app = Consumer.create({
  queueUrl: 'https://sqs.us-east-1.amazonaws.com/account-id/queue-name',
  handleMessage: async (message) => {
    throw new Error('Processing error');
  },
  sqs: new AWS.SQS()
});

app.on('error', (err) => {
  console.error('Error occurred:', err.message);
});

app.on('processing_error', (err) => {
  console.error('Processing error:', err.message);
});

app.start();

Batch Processing

This code sample demonstrates how to process messages in batches. The 'handleMessageBatch' function receives an array of messages, allowing for more efficient processing.

const { Consumer } = require('sqs-consumer');
const AWS = require('aws-sdk');

const app = Consumer.create({
  queueUrl: 'https://sqs.us-east-1.amazonaws.com/account-id/queue-name',
  handleMessageBatch: async (messages) => {
    messages.forEach(message => console.log(message.Body));
  },
  sqs: new AWS.SQS()
});

app.on('error', (err) => {
  console.error(err.message);
});

app.start();

Other packages similar to sqs-consumer

aws-sdk

The aws-sdk package is the official AWS SDK for JavaScript, which includes support for SQS. It provides a more comprehensive set of tools for interacting with AWS services, including SQS. However, it requires more boilerplate code to achieve the same functionality as sqs-consumer.

sqs-producer

The sqs-producer package is designed for sending messages to SQS queues, complementing the sqs-consumer package. While sqs-consumer focuses on consuming messages, sqs-producer is used for producing messages, making them a good pair for full SQS queue management.

node-sqs

The node-sqs package is another library for interacting with SQS. It provides both producing and consuming capabilities but is less specialized and streamlined compared to sqs-consumer, which is focused solely on consuming messages.

README

sqs-consumer

Build SQS-based applications without the boilerplate. Just define a function that receives an SQS message and call a callback when the message has been processed.

Installation

npm install sqs-consumer

Usage

var Consumer = require('sqs-consumer');

var app = new Consumer({
  queueUrl: 'https://sqs.eu-west-1.amazonaws.com/account-id/queue-name',
  region: 'eu-west-1',
  handleMessage: function (message, done) {
    // do some work with `message`
    done();
  }
});

app.on('error', function (err) {
  console.log(err.message);
});

app.start();

• The queue is polled continuously for messages using long polling.
• Messages are deleted from the queue once done() is called.
• Calling done(err) with an error object will cause the message to be left on the queue. An SQS redrive policy can be used to move messages that cannot be processed to a dead letter queue.

API

new Consumer(options)

Creates a new SQS consumer.

Options

• queueUrl - String - The SQS queue URL
• region - String - The AWS region
• handleMessage - Function - A function to be called whenever a message is receieved. Receives an SQS message object as its first argument and a function to call when the message has been handled as its second argument (i.e. handleMessage(message, done)).
• waitTime - Number - An optional time in milliseconds to wait after recieving a message before requesting another one. This enables you to throttle the rate at which messages will be received. (default 100);
• sqs - Object - An optional AWS SQS object to use if you need to configure the client manually

consumer.start()

Start polling the queue for messages.

Events

Each consumer is an EventEmitter and emits the following events:

Event	Params	Description
error	err	Fired when an error occurs interacting with the queue or processing the message.
message_received	message	Fired when a message is received.
message_processed	message	Fired when a message is successfully processed and removed from the queue.