sqs-readable-stream

SQSReadableStream
=========


Create a Readable Node.JS stream from an Amazon Simple Queue Service
(AWS SQS) queue.

By default it will carry on waiting for items on the queue forever, it
will retry on errors and backpreasure is handled appropriately.

Written by Thomas Parslow
(almostobsolete.net and
tomparslow.co.uk) as part of Active Inbox
(activeinboxhq.com).


Install
-------

``bash
npm install --save sqs-readable-stream
`

Example
-------

`javascript
var AWS = require('aws-sdk');
var SQSReadableStream = require('sqs-readable-stream');
var sqs = new AWS.SQS({
apiVersion: '2012-11-05',
region: 'us-east-1',
accessKeyId: 'YOUR AMAZON ACCESS KEY',

});

var sqsStream = new SQSReadableStream({
sqsClient: this.sqsClient,
queueUrl: queueUrl
});

sqsStream.on('data', function (message) {
console.log('New message:', message.Body);
message.deleteMessage(function (err) {
if (err) {
console.log('Failed to delete message')
} else (
console.log('Deleted message');
}
});
});

sqsStream.on('error', function (error) {
console.log('Error receiving messages:', error);
});
`

If you want to process the messages asynchronously while avoiding
overload you might consider using this library with my
through2-concurrent
library. Here's a gist
with some example code.

Messages
--------

The messages passed through the stream are as returned from aws-sdk
with the addition of a deleteMessage method which can be used as a
shortcut to delete the message from the queue.

Constructor Options
-------

The following options can be passed into the constructor.

- sqsClient (required) :: An instance of the SQS class from the
AWS SDK (or something else that acts like one)
- queueUrl (required) :: The URL of the SQS Queue to read from
- receiveMessageOptions :: Options to pass into the calls to
receiveMessage. Defaults to:

`javascript
{
AttributeNames: [ 'All' ],
MaxNumberOfMessages: 10,
WaitTimeSeconds: 20
}
`

- retryOnErrors (default: true) :: Controls whether it will retry
after receiving errors from SQS.
- initialBackoff (default: 100) :: Time (ms) to wait for first retry
(will increase by doubling for each consecutive error)
- maxBackoff (default: 15000) :: Maximum time (ms) to wait for a retry
- stopOnQueueEmpty (default: false) :: Controls whether it will stop
(eg emit and end` event and stop requesting new messages) when the
Queue is empty. The default behaviour is to wait for new items
forever.

Contributing
------------

Fixed or improved stuff? Great! Send me a pull request through GitHub or get in touch on Twitter [@almostobsolete][#tom-twitter] or email at tom@almostobsolete.net

[#tom]: http://www.almostobsolete.net
[#tom-twitter]: https://twitter.com/almostobsolete