sqs

SQS Bindings

This document defines how to describe SQS-specific information on AsyncAPI.

SQS can be used both stand-alone as a point-to-point and paired with SNS and as a publish-subscribe channel (where SQS is the endpoint that SNS delivers messages to). For this reason we define a Queue schema, and reference that schema from both a Channel Binding Object and a publish Operation Binding Object.

For point-to-point scenarios, use the Channel Binding Object, as producers send to the queue and consumers receive from it directly.

For publish-subscribe scenarios, use as a publish Operation Binding Object, as the producer sends to SNS and the consumer receives via SQS.

Version

Current version is 0.3.0.

Server Binding Object

This object MUST NOT contain any properties. Its name is reserved for future use.

Channel Binding Object

Use the Channel Binding Operation for Point-to-Point SQS channels.

There are three likely scenarios for use of the Channel Binding Object:

• One file defines both publish and subscribe operations, for example if we were implementing the work queue pattern to offload work from an HTTP API endpoint to a worker process. In this case the channel would be defined on the Channel Object in that single file.
• The producer and consumer both have an AsyncAPI specification file, and the producer is raising an event, for example interop between microservices, and the producer 'owns' the channel definition and thus has the SQS Binding on its Channel Object.
• The producer and consumer both have an AsyncAPI specification file, and the consumer receives commands, for example interop between microservices, and the consumer 'owns' the channel definition and thus has the SQS Binding on its Channel Object.

An SQS queue can set up a Dead Letter Queue as part of a Redelivery Policy. To support this requirement, the Channel Binding Object allows you to define both a Queue Object to use as the Channel or target in a publish Operation and a Dead Letter Queue. You can then refer to the Dead letter Queue in the Redrive Policy using the Identifier Object and setting the name field to match the name field of your Dead Letter Queue Object. (If you define the DLQ externally, the Identifier also supports an ARN).

Fields

Field Name	Type	Description
queue	Queue	Required. A definition of the queue that will be used as the channel.
deadLetterQueue	Queue	Optional. A definition of the queue that will be used for un-processable messages.
bindingVersion	string	Optional, defaults to latest. The version of this binding.

Schemas

Queue

Field Name	Type	Description
name	string	Required. The name of the queue. When an SNS Operation Binding Object references an SQS queue by name, the identifier should be the one in this field.
fifoQueue	boolean	Required. Is this a FIFO queue?
deduplicationScope	string	Optional. Specifies whether message deduplication occurs at the message group or queue level. Valid values are messageGroup and queue. This property applies only to high throughput for FIFO queues.
fifoThroughputLimit	string	Optional. Specifies whether the FIFO queue throughput quota applies to the entire queue or per message group. Valid values are perQueue and perMessageGroupId. The perMessageGroupId value is allowed only when the value for DeduplicationScope is messageGroup. Setting both these values as such will enable high throughput on a FIFO queue. As above, this property applies only to high throughput for FIFO queues.
deliveryDelay	integer	Optional. The number of seconds to delay before a message sent to the queue can be received. Used to create a delay queue. Range is 0 to 15 minutes. Defaults to 0.
visibilityTimeout	integer	Optional. The length of time, in seconds, that a consumer locks a message - hiding it from reads - before it is unlocked and can be read again. Range from 0 to 12 hours (43200 seconds). Defaults to 30 seconds.
receiveMessageWaitTime	integer	Optional. Determines if the queue uses short polling or long polling. Set to zero (the default) the queue reads available messages and returns immediately. Set to a non-zero integer, long polling waits the specified number of seconds for messages to arrive before returning.
messageRetentionPeriod	integer	Optional. How long to retain a message on the queue in seconds, unless deleted. The range is 60 (1 minute) to 1,209,600 (14 days). The default is 345,600 (4 days).
redrivePolicy	Redrive Policy	Optional. Prevent poison pill messages by moving un-processable messages to an SQS dead letter queue.
policy	Policy	Optional. The security policy for the SQS Queue
tags	Object	Optional. Key-value pairs that represent AWS tags on the queue.

Identifier

Field Name	Type	Description
arn	string	Optional. The target is an ARN. For example, for SQS, the identifier may be an ARN, which will be of the form: "arn:aws:sqs:{region}:{account-id}:{queueName}"
name	string	Optional. The endpoint is identified by a name, which corresponds to an identifying field called 'name' of a binding for that protocol on this publish Operation Object. For example, if the protocol is 'sqs' then the name refers to the name field sqs binding

Policy

Field Name	Type	Description
Statements	Statement	Required. An array of Statement objects, each of which controls a permission for this queue.

Redrive Policy

Field Name	Type	Description
deadLetterQueue	Identifier	The SQS queue to use as a dead letter queue (DLQ)
maxReceiveCount	integer	Optional. The number of times a message is delivered to the source queue before being moved to the dead-letter queue. Default is 10.

Statement

Field Name	Type	Description
effect	string	Required. Either "Allow" or "Deny"
principal	string or AWS principal property containing a string or string array	Required. The AWS account(s) or resource ARN(s) that the statement applies to
action	string or array of string	Required. The SNS permission being allowed or denied e.g. sns:Publish
resource	string or array of string	Optional. The resource(s) that this policy applies to
condition	object or list of objects	Optional. Specific circumstances under which the policy grants permission

Operation Binding Object

SQS Point-To-Point

Because we have defined Queue as part of the Channel Binding Binding object, we do not require Binding information for the publish Operation Object of the subscribe Operation Object. You can use an empty Queue object ({}) to denote the Binding on the Operation Object, if you want to indicate the protocol used to send or receive for generation purposes such as Infrastructure As Code.

SNS to SQS Pub-Sub

Use the Operation Binding Object when SQS is listening to an SNS Topic. In this case we need to define both an SQS Operation Binding Objects on the receiver publish Operation Object to represent the queue definition and we need to define an SNS Operation Binding Object to define the Subscription to SNS that makes your queue a receiver of that endpoint.

Assuming you have separate AsyncAPI specifications for the producer and the consumer, we would assume the following bindings would appear for an SNS producer and an SQS consumer.

Producer: SNS Channel Binding Object, SNS subscribe Operation Binding Object [if required] Consumer: SNS publish Operation Binding Object, SQS publish Operation Binding Object

• We assume that the SNS binding information only needs to be present in the producer file (although defining it in both is allowable) and any infrastructure as code dependencies can recognize this.

On an Operation Binding Object we support an array of Queue objects. Members of this array may be Queue Objects that define the endpoint field required by an SNS Operation Object delivering by the SQS protocol or Queue Objects that define the Dead Letter Queue used by either the Redrive Policy of the SNS Subscription (see the SNS Binding Object) or the Redrive Policy of the SQS Queue. The name of the Queue Object is used by an Identifier field on either the endpoint field of the SNS Operation Object of deadLetterQueue on the Redrive Policy to identify the required member of this array.

Fields

Field Name	Type	Description
queues	[Queue]	Required. Queue objects that are either the endpoint for an SNS Operation Binding Object, or the deadLetterQueue of the SQS Operation Binding Object
bindingVersion	string	Optional, defaults to latest. The version of this binding.

Examples

SQS Point-To-Point

In this example, we are using SQS for a point-to-point channel. For this example, we assume that we are defining two microservices that communicate over a shared SQS channel, with the consumer receiving events over that channel and the producer owning the channel definition.

The producer file would look like this:

channels:
  user-signedup:
    bindings:
      sqs:
        queue:
          name: user-signedup-queue
          fifoQueue: false
          receiveMessageWaitTime: 4
          redrivePolicy:
            deadLetterQueue:
              name: user-signedup-dlq
          policy:
            statements: 
            - effect : Allow
              principal: *
              action: Sqs:SendMessage
            - effect : Allow
              principal: *
              action: Sqs:ReceiveMessage
        deadLetterQueue: 
          name: user-signedup-dlq 
          messageRetentionPeriod: 1209600 
	        fifoQueue: false
    subscribe:
      operationId: sendMessage
      description: sends messages when a user has signed up
      bindings:
        sqs: {}

In this case we can minimize duplicated information by omitting the binding in our specification, and assume it is picked up from the producer file. We can use an empty object to indicate the SQS Binding on the publish Operation Object, if need a marker for generation, otherwise we could omit the Operation Binding Object.

channels:
  user-signedup:
   publish:
      operationId: receiveMessage
      description: receives a messages when a user has signed up
      bindings:
        sqs: {}

SNS to SQS Pub-Sub

In this example, we are using SNS for the channel, and SQS to receive from SNS.

The producer files looks like this (see the SNS Binding for more).

channels:
  user-signedup:
    description:  A user has signed up for our service
    binding :
      sns: {}     # Indicates that the channel is an SNS Topic
    subscribe:
      operationId: sendMessage
      description: send messages to the topic
      bindings:
        sns:
          policy:
            statements: 
            - effect : Allow
              principal: *
              action: SNS:Publish

And the consumer file would look like this. Note that for simplicity, we choose not to repeat the SNS Binding on the Consumer as it does not 'own' the channel.

channels:
  user-signedup:
    description:  A user has signed up for our service
    publish:
      operationId: receiveMessage
      description: receive messages from the topic
      bindings:
        sns:
          consumers:
          - protocol: sqs
            endpoint:
            name: user-signedup-queue
            rawMessageDelivery: true  
            filterPolicy:
              attributes:
                reason: 
                  anything-but: password-reset
            redrivePolicy:
              deadLetterQueue:
              name: user-signedup-queue-dlq
        sqs:
          queues:
          - name: user-signedup-queue
            fifoQueue: false
            receiveMessageWaitTime: 4
            policy:
              statements: 
              - effect : Allow
                principal: *
                action: Sqs:SendMessage
              - effect : Allow
                principal: *
                action: Sqs:ReceiveMessage 
          - name: user-signedup-dlq 
            messageRetentionPeriod: 1209600 
            fifoQueue: false

Message Binding Object

This object MUST NOT contain any properties. Its name is reserved for future use.