How Does Amazon Simple Queue Service (SQS) Work?

Zeeshan Riaz April 26, 2022

Amazon simple queue service, (SQS), allows you to send, store and retrieve multiple messages asynchronously of various sizes.

It permits users to decouple their applications, distributed systems, and serverless microservices from one another. As well as scaling them, they do not require their users to maintain and establish their message queues.

amazon simple queue service

What does Amazon Simple Queue Service (SQS) do?

Developers can exchange messages between components of software securely using Amazon SQS. The Amazon Simple Queue Service (SQS) interface enables users to access the service through any common programming language.

Amazon SQS supports asynchronous tasks. In a nutshell, this means that rather than a single application calling another directly, the app can spend time waiting in a queue while it sends a message. These messages will then be made available to other applications.

SQS’s key features

Amazon Simple Queue Service (SQS) offers queue functionality as an independent cloud service. Through a connection, the software communicates with SQS without using the credentials or the queue name. Applications can also create custom queues and delete them in SQL.

In Amazon SQS, two queue types are available to meet the needs of different applications:

Standard Queues

  • Unlimited Throughput. A queue of standard actions is capable of supporting nearly unlimited transactions per second.
  • At-Least-Once Delivery. There is usually at least one copy of each message, but there may be multiple copies.
  • Best-Effort Ordering. On occasion, messages may arrive in an order other than the one they were sent.

Queues with FIFO

  • High Throughput. FIFO queues operate by default at a maximum rate of 300 messages per second (300 sends, receives, or deletes per second). FIFO queues can accommodate up to 3,000 messages per second when you batch 10 messages per operation (maximum). 

FIFO’s high throughput mode can be enabled through the Amazon SQS console if you require higher throughput. With batching, it will be possible to process up to 30,000 messages per second.

  • Exactly-Once Processing. The message is sent once and remains available until it is processed and deleted by the recipient. No duplicate messages are introduced.
  • First-In-First-Out Delivery. There is strict ordering applied to the flow of messages (i.e., First-In-First-Out).

The Amazon Simple Queue Service provides the following functionality

  • Messages and queues are unlimited. You can easily create a wide range of Amazon SQS queues to store a large number of messages in any region you like
  • The size of the payload. There is no restriction on the size or format of message payloads, they can contain as much text as they like. It is considered necessary to bill each 64 KB chunk of the payload as a separate request. One API call that contains a 256 KB payload, for instance, will be billed as four requests. 

Amazon SQS provides an extended Java client library that uses Amazon Simple Storage Service (S3) to store messages larger than 256 KB. Payload references are sent via Amazon SQS.

  • Batches. Enable the sending, receiving, or deletion of messages in batches of up to ten or 256 KB in size. SQS can be even more cost-effective for customers who use batching since it costs the same as single messages.
  • Long-term polling. In order to minimize cost and receive messages as quickly as possible, reduce the number of unnecessary polls. The time it takes for a long-poll request to arrive when your queue is empty is approximately 20 seconds. Both long poll requests and regular poll requests are charged at the same rate.
  • Messages can be held in the queue for up to 14 days.
  • You can read and send messages at the same time.
  • Locking of messages. Upon receiving a message, it becomes “locked” and cannot be accessed until it has been processed. This lock prevents the subsequent processing of other messages. A message processing failure will result in the lock expiring, allowing the message to be accessed again.
  • Shared queueing. Provide anonymous or specific AWS account access to Amazon SQS queues. It is also possible to restrict queue sharing by IP address and time of day.
  • Encryption on the server-side (SSE). AWS Key Management Service (AWS KMS) provides security for messages in Amazon SQS queues. Upon receiving messages from Amazon SQS, SSE encrypts the messages. Amazon SQS stores messages in encrypted form, and it decrypts them only after an authorized subscriber receives them.
  • The Dead Letter Queue (DLQ). DLQs are used to handle messages that consumers have not been able to process. If an Amazon SQS message receives more than its maximum receive count, it is moved to the DLQ for that queue. 

There must be a similar queue type to the queue used for the source (standard or FIFO). To understand why your consumer has not been able to receive the message, you can inspect the messages in DLQs. The messages can be moved from the DLQ to the corresponding source queues if the issues have been resolved.

The advantages of Amazon SQS over other message queueing systems

It requires advanced skills to develop software to manage message queues. Depending on the custom requirements and the configuration required, there may be some prepackaged options available. As well as constant investment in hardware maintenance and admin resources, these alternatives also require redundant storage. In this regard, Amazon Simple Queue Service (SQS) can avoid such problems since it eliminates the need for additional time and resources.

Because Amazon SQS allows its components to be decoupled, it delivers high-performance standards. Individual components are independent of each other, and they fail independently. Therefore, the system is more reliable and fault-tolerant as a whole.

It is not necessary to have the same queues on Amazon SQS. A user may, for instance, define a default delay for a particular queue. 

Amazon Simple Storage Service and Amazon DynamoDB allow users to store messages over a certain size or split larger ones into smaller ones.

Can messages in Amazon SQS message queues be retained for a long time?

It is possible to retain Amazon SQS messages for a long period of time. Therefore, messages are produced for a longer period of time before they are ultimately picked up from the queue and consumed.

You can choose from a range of message retention periods with Amazon SQS. By default, the system retains messages for four days. When the message retention quota is reached, messages are automatically deleted.

How large can a message queue in Amazon SQS be?

Amazon Simple Queue Service (SQS) message queues do not have an upper limit on the number of messages sent. When a consuming component has been in receipt of a message but has not yet deleted the message from the queue, the message is considered in-flight. It is worth noting that the system has different limits for in-flight messages depending on the type of queue. 

Amazon SQS allows 120,000 messages per minute for the FIFO queue, and for the standard queue, 120,000. A user may create an unlimited number of message queues, but the queue name must not exceed 80 characters in length.

Security and compliance for Amazon SQS messages

It is possible for developers to encrypt data sent or received between applications on the server to ensure that the information is secure. Every time encryption keys are used, AWS Key Management Service automatically logs the event in AWS CloudTrail. Compliance with data management regulations can be ensured through this process.

Pricing information for Amazon Simple Queue Service

No upfront costs are associated with Amazon SQS, and no infrastructure needs to be purchased, deployed, built, or maintained. SQS’ pricing structure is based on usage so that it can be significantly cheaper than the always-on pricing of self-managed messaging middlewares.

In the Free Tier of AWS, Amazon SQS users are permitted to send and receive up to 1 million Amazon SQS messages per month for free.

Compatibility with Amazon SQS

Several other AWS products are compatible with Amazon’s Simple Queue Service (SQS). This includes Amazon Relational Database Service, Amazon Elastic Compute Cloud, etc.

Where can I access Amazon SQS?

Using the console:

Logging into your Amazon Web Services account will enable you to access the Amazon Simple Queue Service (SQS) 

  • You can find Amazon SQS under the Application Integration section of My Account -> AWS Management Console -> Click on Services.
  • You will be directed to the Amazon SQS Create Queue page by clicking this button.

How to use CLI (Command Line Interface):

The AWS CLI can be used to launch tasks on a whim, for example, launching a queue. As well as embedding Amazon SQS functionality into utilities, it can be used as a command-line tool.

Obtaining an access key ID and secret access key is required before you can use the AWS CLI with Amazon SQS. 

API usage:

Amazon SQS can be utilized by using AWS SDKs. These SDKs support Java, JavaScript, Node.js, Ruby, C++, Python, PHP, etc.


What is SQS used for?

Amazon Simple Queue Service (SQS) allows distributed applications to send and receive messages through a polling model. By decoupling sending and receiving, applications can improve performance and efficiency.

What is SQS, and how does it work?

Message queues are in their simplest form, SQS. An exchange of messages between two components of a distributed system requires a temporary repository. As long as a service does not process these messages, they will remain in the queue.

What is an SQS example?

Here is an example of a website that generates Memes. Suppose a user uploads a photograph and wishes to make it into a meme. In the case that a user uploads a photo to a website, that photo might be stored in S3. 

The moment the upload has been completed, a Lambda function is invoked. Lambda transmits the data about the particular image to SQS, which can include “what a meme should say at the top,” “what a meme should say at the bottom,” and the location of the S3 bucket, etc. 

As a message, the data resides in the SQS. This message is examined by an EC2 instance. A Meme is created and stored in S3 by an EC2 instance. As soon as the EC2 instance has completed its tasks, it is returned to the SQS. If your EC2 instance was lost, you would not lose your job as it would reside within your S3 bucket.


Therefore, we found that AWS SQS provides the possibility to send unlimited numbers of messages in any geographical region. There is a maximum of 256 KB of text in a message payload. This extended client library for Java Programming will not be able to handle large text files.

It is possible to share Simple Queue Service (SQS) queries anonymously with some AWS accounts or specific accounts. You can send and read messages at the same time. IP addresses and periods of time can be specified for the sharing process.

With the AWS Key Management Service, the contents of AWS SQS messages can be secured. SQS users are able to use SQS more effectively with this feature.

Leave a Reply

Your email address will not be published. Required fields are marked *