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AWS High Availability SQS

This library makes it easy to write SQS messages with high availability. It includes the following features:

• Send any size message to SQS. If a message is too large, it will be stored in S3 and a reference to it will be stored in SQS.
• Send a message to one of multiple backup queues if the primary queue is unavailable.

Setup

You should set up at least 2 SQS queues and 2 S3 buckets in separate regions. The SQS queues are the messages you want to process. The S3 buckets will be used for oversized queue messages that are sent.

S3 Lifecycle Rules

When deleting SQS messages that were backed by an S3 file, the code will attempt to delete the S3 file as well. However, in some cases, that S3 files may not be deleted. For example, it it advised to catch and ignore AwsHighAvailabilitySqsDeleteS3FileDeletionFailureException exceptions when calling AwsHighAvailabilitySqsReceiver::deleteMessage. Also, any messages that expire from the queue or end up going to the dead letter queue will note have the file deleted. Therefore, it is advised to set up lifecycle rules on the S3 bucket. You can find instructions on setting up object expiration at https://docs.aws.amazon.com/AmazonS3/latest/userguide/lifecycle-expire-general-considerations.html. 30 days is a safe bet.

Usage

The APIs require you to pass in an \Aws\Sdk object. In the examples below, $awsSdk is used for this object.

Sending an SQS Message

1. Create a list of available SQS queues to send to.
   • This is an SqsAvailableQueues object, which includes a primary queue and optional alternative queues.
2. Create a list of S3 buckets to back large messages.
   • This is and S3AvailableUploadFileBucketAndKeyLocations object.
   • You can add anything that implements S3FileBucketAndKeyProviderInterface to the list of locations.
   • The simplest option is to use S3FileBucketAndKey, which implements this interface.
3. Set up SqsMessageSendingMetadata with metadata for the message to be sent.
4. Create an AwsHighAvailabilitySqsSender object and call sendMessageWithS3LargeMessageBacking.
   • You can use the returned object to get the queue used and the message ID

SqsMessageSendingMetadata Options

The SqsMessageSendingMetadata class allows you to customize the following when sending messages:

• SQS delivery delay.
• SQS message attributes.

Receiving SQS Messages

1. Create an SqsAvailableQueue object with the queue you want to receive from.
2. Set up SqsMessageReceivingMetadata with metadata for receiving messages.
3. Create an AwsHighAvailabilitySqsReceiver object and call receivedMessagesWithS3LargeMessageBacking.
   • The returned object includes the SQS messages, which you can get using getSqsMessages.

SqsMessageReceivingMetadata Options

The SqsMessageReceivingMetadata class allows you to customize the following when receiving messages:

• Maximum number of messages to received (default: 10)
• SQS visibility timeout for messages received.
• SQS wait time when receiving messages.

Deleting SQS Messages

1. Create an SqsAvailableQueue object with the queue you want to delete from.
2. Create an AwsHighAvailabilitySqsReceiver object and call deleteMessage.
   • For any failures, a AwsHighAvailabilitySqsDeleteException will be thrown.
   • However, if a AwsHighAvailabilitySqsDeleteS3FileDeletionFailureException exception is thrown, the SQS message will have been successfully deleted, so it's advisable to ignore the exception besides possibly logging it.