azure-queue-consumer

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

Installation

npm install azure-queue-consumer --save

Usage

const Consumer = require('azure-queue-consumer');

const app = Consumer.create({
  queueUrl: 'https://account-name.queue.core.windows.net/queue-name',
  handleMessage: (message, done) => {
    // do some work with `message`
    done();
  }
});

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

app.start();

• The queue is polled every second by default.
• Messages are deleted from the queue once done() is called.
• Messages are processed one at a time.

Credentials

By default the consumer will look for Azure credentials in the places specified by the Azure Storage SDK. The simplest option is to export your credentials as environment variables:

export AZURE_STORAGE_CONNECTION_STRING=...

If you need to specify your credentials manually, you can use a pre-configured instance of the Azure QueueService:

const Consumer = require('azure-queue-consumer');
const azureStorage = require('azure-storage');

const app = Consumer.create({
  queueUrl: 'https://account-name.queue.core.windows.net/queue-name',
  handleMessage: (message, done) => {
    // ...
    done();
  },
  queueService: azureStorage.createQueueServiceWithSas(
    'https://account-name.queue.core.windows.net/queue-name',
    '<SAS Token>'
  );
});

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

app.start();

API

Consumer.create(options)

Creates a new Azure data queue consumer.

Options

• queueUrl - String - The Azure data queue URL
• handleMessage - Function - A function to be called whenever a message is received. Receives a queue 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)).
• pollDelaySeconds - Number - The delay (in seconds) between queue polling attempts while the queue is empty.
• waitTimeSeconds - Number - maximum execution time across all potential retries, for requests made via the Queue service.
• authenticationErrorTimeout - Number - The duration (in milliseconds) to wait before retrying after an authentication error (defaults to 10000).
• queueService - Object - An optional Azure QueueService instance to use if you need to configure the client manually

consumer.start()

Start polling the queue for messages.

consumer.stop()

Stop polling the queue for messages.

Events

Each consumer is an EventEmitter and emits the following events:

|Event|Params|Description| |-----|------|-----------| |error|err, [message]|Fired when an error occurs interacting with the queue. If the error correlates to a message, that error is included in Params| |processing_error|err, message|Fired when an error occurs 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.| |response_processed|None|Fired after one batch of items (up to batchSize) has been successfully processed.| |stopped|None|Fired when the consumer finally stops its work.| |empty|None|Fired when the queue is empty (All messages have been consumed).|

Credits

Inspired by SQS Consumer