AWS SQS vs SNS vs EventBridge: How to Choose a Messaging Service Provider?

Applications in today’s cloud architecture are separated into smaller, independent building parts that are simpler to create, deploy, and manage. Messaging services, when implemented properly, can increase an application’s resilience, availability, and scalability. They can also give your apps extensibility for upcoming service features and versions, allowing them to interface with resources outside of your workload or even the AWS Cloud.   

 AWS messaging services allow various software programmes and endpoints to exchange data while operating on a variety of platforms and programming languages. With these services, you can transmit and receive data in your cloud apps. To support the dependability of your applications, the underlying infrastructure is automatically provided for high availability and message durability. Three services for message orchestration are provided by AWS namely AWS SQS, SNS, and EventBridge. Each of these services offers a variety of extremely diverse features despite having names that are fairly similar.  

 In this blog post, we are going to compare the primary messaging services offered by Amazon Web Services– The AWS SQS, AWS SNS, and AWS EventBridge.     

About AWS Messaging Services    

Event buses, publish/subscribe queues, and publish/subscribe events are all useful messaging patterns for serverless developers. These services are offered in AWS respectively via, Amazon SQS, Amazon SNS, and Amazon EventBridge. Using any of them can help you publish messages using the AWS SDK and call functions as targets. In serverless architectures, each of these services has a significant function to play.  

A combination of several AWS services, microservices, and AWS Lambda functions is used in the majority of serverless application architectures. The majority of production serverless workloads depend on messaging services, which are crucial for enabling distributed applications to communicate with one another.   

These services can initially appear to be relatively similar since they essentially decouple the producer from the consumer, which is what they both accomplish. The design of these messaging services is loosely linked and asynchronous. But if you look closely, these services offer various capacities.  

Now let’s examine three major Amazon messaging offerings, SQS, SNS, and EventBridge. After reviewing each product’s features and services independently, we will compare which messaging service offers the best solutions for serverless applications.  

 What is AWS SQS?   

SQS, or simple queue service, is one of the earliest services created and introduced by AWS. SQS wasn’t launched until S3 (Simple Storage Service) was released in July 2006. 

Your serverless apps can use queues provided by SQS. In your workload, you can leverage a queue to send, store, and receive messages between various services. Queues serve to decouple various components of your application and are a key mechanism for distributed systems fault tolerance. With SQS, there is no upper limit on the number of messages that can be stored in a queue. Until they are processed by a downstream customer, the service persistently holds onto messages. 

SQS is primarily used to provide asynchronous communication between services and to help with application separation. Developers can publish messages to a queue using SQS, which the consuming application can then handle immediately or later. 

SQS provides two different message queue types. Standard queues deliver maximum throughput, best-effort ordering, and at least once delivery. In SQS FIFO queues, messages are processed exactly once the order is sent. 

Key features offered by SQS 

• processing of the events in order 
• only one consumer can view a single message when using long-polling by the consumer 
• scaling that is economical and automatic 
• message-based consumer invokes cannot be made (needs SNS message filtering for this) 
• available KMS message encryption at rest 
• compliant with HIPAA   

AWS SQS Core Concepts 

• Queues  

Queues are highly prioritized by AWS. They are things that you, the user, will construct using the console, CLI, or IaC. Queues are the place where you, the owner of the application, will post messages. Until a consuming application gets and processes the messages, content pushed to the queue will remain available. When a thread attempts to process a message in a queue, that message is said to have been “claimed” and becomes unavailable to other threads until it has been successfully processed (and has thus been erased) or a timeout has occurred (timeout duration is configurable).  

• Messages 

The content of the queue is known as a message. A JSON object particular to your application is typically contained in each message, which is the single point of entry in the queue.   

• Polling 

The consumer of the queue will process the messages by polling. It is possible to poll a queue for one or more messages. After a consuming application polls the queue and acquires messages, they become invisible to all other consuming applications. There is a short polling option as well as a long polling option in SQS. 

SQS can receive messages from numerous producers, and the consumers will be able to remove them from the queue. Although there may be numerous consumers, each message will only be read by one of them. Because of this, the standard strategy is to have a single application read from the queue. With many application instances, such as a number of Lambda function contexts or an army of EC2 computers, you can parallelize processing, though. 

The long-polling option lets the consumer wait until there is a message or the polling time has expired before calling the SQS. Moreover, SQS is highly scalable, you don’t need to set its throughput capacity. All you need to do is send what you need. 

Benefits of AWS SQS 

• Reduce administrative costs 

The infrastructure and continuous operations required to deliver a highly available and scalable message queuing service are managed by AWS. With SQS, there are no up-front costs, no need for purchasing, setting up, and configuring messaging software, and no time-consuming infrastructure build-out and upkeep. SQS queues are automatically scaled and formed dynamically, allowing for speedy and effective application development. 

• Deliver messages consistently 

Send any amount of data through Amazon SQS without missing messages or needing to use another service. SQS enables you to decouple application components so that they function and fail separately, enhancing the system’s overall fault tolerance. Every communication is redundantly stored in several Availability Zones in order to have multiple copies available at all times. 

• Secure sensitive data. 

Server-side encryption (SSE) can be used to encrypt each message body while sending and receiving private information between applications utilizing Amazon SQS. You can centrally manage the keys that safeguard SQS messages as well as the keys that protect your other AWS resources thanks to the integration of Amazon SQS SSE with AWS Key Management Service (KMS). To assist you in meeting your regulatory and compliance demands, AWS KMS logs each usage of your encryption keys to AWS CloudTrail. 

• Highly scalable at a reasonable price 

To scale up and down according to demand, Amazon SQS uses AWS. Because SQS scales elastically with your application, you won’t need to bother about capacity planning or pre-provisioning. The maximum number of messages that may be stored in a queue is indefinite, and typical queues offer virtually infinite throughput. The “always-on” approach of self-managed messaging middleware is replaced with usage-based pricing, which results in a large cost decrease.   

What is Amazon SNS ?

Simple Notification Service (Amazon SNS) is a managed service designed to deliver messages from publishers to subscribers. By sending messages to a topic—a logical access point and communication channel—publishers engage in asynchronous conversation with subscribers. Clients can subscribe to the SNS topic and subscribe to published messages using a supported endpoint type, such as Amazon Kinesis Data Firehose, Amazon SQS, AWS Lambda, HTTP, email, push notifications, and text messages. 

Multiple recipients who are interested in receiving notifications from publishers are a problem that SNS attempts to address. With this solution, we can notify multiple apps at once when a change is made to a given entity, resolving the one-by-one issue presented by SQS.   

Core Concepts of AWS SNS   

• Topic   

The topics are of main value in SNS. In the sense that messages are published to them, they are similar to queues, but they do not retain state. They merely serve as an endpoint for publishing applications to write to, and then rely on SNS to disseminate a copy of that message out to all receivers. They do not “keep” messages. To put it another way, Topics enable fan-out notifications to numerous clients. Typically, topics are developed with a specific theme in mind.    

• Messages   

Messages are simply JSON chunks with data in the payload. The downstream subscribers receive identical messages during the publishing process.   

• Publish/Subscribe   

The terms “publish/subscribe” and “pubsub” are used to refer to the interactions between data owners and consumers. The publisher or topic owner would be the program or person who is the owner of the data. Additionally, a customer or subscriber is an application or a person that wants to use the data. 

The publisher-subscriber structure is the foundation of the AWS Simple Notification Service (SNS), a notification service. Below are some of the important functionalities offered by AWS SNS,    

• can have numerous consumers, including Lambda, HTTP, SQS, and others. 
• Message Asynchronous event alerts provided by Fanout enable parallel processing. 
• the message may be used to call the subscriber 
• when using KMS, messages can be encrypted at rest
• SNS complies with HIPAA regulations.

Benefits offered by AWS SNS  

• Utilize batching and message filtering to simplify processes and cut costs. 

You may simplify your application design and cut costs with the aid of Amazon SNS. Publisher systems can send up to 10 messages with message batching in a single API call. Subscriber systems only receive the messages they are interested in thanks to message filtering. See Message Filtering and Message Batching for further information.   

• Message deduplication and sorting help to ensure accuracy 

When used with Amazon SQS FIFO queues, Amazon SNS FIFO topics make sure that messages are delivered strictly in order and are only processed once. As a result, you can continue to perform transactions accurately and consistently when using a single or a number of independent services. See Message Ordering and Message Deduplication for further information.   

• Boost security with message privacy and encryption 

To prevent unauthorized access to your messages, Amazon SNS offers encrypted topics. 256-bit AES-GCM is used for encryption, and a customer master key (CMK) supplied by AWS Key Management Service is used (KMS). As a result, you can securely publish messages to Amazon SNS topics from an Amazon Virtual Private Cloud (VPC) subnet without going through the Internet thanks to Amazon SNS’s support for VPC endpoints via AWS PrivateLink.   

• DLQ, delivery retries, and message archiving can all be used to increase durability 

Each communication posted across multiple, geographically distinct data centers is stored by Amazon SNS. Amazon SNS implements a message delivery retry strategy in the absence of a subscribed system. Amazon SNS can transfer messages to dead-letter queues in order to preserve any messages that cannot be delivered before the delivery retry policy expires (DLQ). By using Amazon Kinesis Data Firehose subscriptions, Amazon SNS can also archive communications in Amazon S3.     

 What is AWS EventBridge?   

Using Amazon EventBridge, you can build event-driven applications at scale using events generated by your applications, Software-as-a-Service (SaaS) integrations, and AWS services. Targets like AWS Lambda and other SaaS applications receive a stream of real-time data from event sources like Zendesk or Shopify. You can create application architectures that respond instantly to your data sources using routing rules, entirely decoupling the event publisher and consumer. 

Similar to SNS, EventBridge enables the broadcasting of messages to subscribers for independent processing. Let’s examine the key concepts included in the EventBridge ecosystem. 

Launched in July 2019, EventBridge is a more recent service in the AWS ecosystem. It has many traits with AWS SNS and offers a variety of other value-added features that simplify the life of developers. The following are a few of this service’s important attributes: 

• offers excellent SaaS application integration options with third-party applications. 
• capable of changing events before transmitting 
• message-based event filtering and routing 
• KMS doesn’t use any at-rest encryption. 
• it is not kept in message order. 
• it has a feature called Schema Registry/Discovery 
• message archiving is possible   

Core Concepts of EventBridge 

• Message Bus 

Message Buses accept events that need to be disseminated to downstream users, just like SNS topics do. 

• Events 

In the context of SNS and SQS, events are comparable to messages but have a better moniker. They are JSON blobs that contain information about the event’s source and payload. A cron expression can be used to “schedule” events such that they run on a regular schedule. For those of you wishing to run timed batch jobs on a regular basis at a specific time of day, this is helpful. 

• Targets 

Events that are published to the message bus are received downstream by targets. extremely comparable to SNS users. 

• Rules 

Routing logic for Message Buses is provided via rules. In essence, you can set up rules so that a message won’t be broadcast to a specified target until a specific circumstance (inside the message data itself) is met. You define an Event Pattern when you want to align the message’s content with a specific destination. There are a maximum of 5 targets per rule, however, you can have several rules that match various patterns. If you want more, you must construct a new rule using the same event pattern and various defined targets. 

Benefits of Using EventBridge   

• Create event-driven architectural designs. 

EventBridge makes it easier to create event-driven systems. Because you may filter and publish straight to EventBridge, your event targets don’t need to be aware of the event sources. No setup is necessary. Increase application resilience and developer agility using loosely linked event-driven architectures. 

• Sync SaaS applications 

Without building bespoke integration code, EventBridge ingests data from supported SaaS applications and directs it to AWS services and SaaS targets (via API destinations – an HTTP invocation endpoint target for events). You may link your SaaS apps with EventBridge, or you can use events from your SaaS apps to start workflows for customer service, business operations, and other purposes.   

• Fewer custom codes 

Application connectivity is facilitated via EventBridge. With no special code needed, events may be ingested, filtered, transformed, and sent. You can download code bindings for these event schemas in your IDE and save events as strongly-typed objects in your code by using the EventBridge schema registry, which keeps a collection of easily-located event schemas. Utilize the feature of the schema discovery to automatically add schemas found from your event bus to the registry.   

• Lower operational costs 

There are no servers to set up, patch, or maintain with EventBridge. There isn’t any extra software to set up, maintain or use. EventBridge scale automatically based on the volume of events ingested, and you only pay for events broadcast by your AWS or SaaS apps. Distributed availability and fault tolerance are features that come with EventBridge. It is also simpler to recover from errors or create a new application state using historical events thanks to EventBridge’s native event archive and replay functionality.   

AWS SQS vs SNS vs EventBridge: Which One To Go For? 

Now comes the million-dollar question, which messaging service is the best? Which one to go for? The answer is- it depends. In this article, we have covered a variety of features and benefits these services offer. It is clear that each of them offers functionalities that serve a certain set of requirements. So, to leverage any one of the above services depends on your applications’ needs and requirements. But let us do a final review before we conclude.   

You should go for SQS if, 

• You’re trying to separate your applications from one another by using dependable 1:1 asynchronous communication. 
• Due to a database bottleneck or another reason, you want to rate-limit the number of texts you read. 
• It is important that vent messages are processed in an organized manner.   

You should choose SNS, if

• With just one step, you want to publish messages to a variety of subscribers. 
• For publishing and delivering content to customers, high throughput and dependability are required. 
• have a significant audience   

Choose Eventbridge if, 

• You want to distribute communications to a large number of subscribers, and you want to leverage event data to match targets with similar interests. 
• You desire integration with other SaaS companies, like Shopify, Datadog, Pagerduty, and others. 
• If you want to quickly find schemas produced by other teams and include them in your application. 
• You wish to employ recurring events with a cron-like expression to deliver messages to your event bus on a regular basis.   

Final Thoughts 

Serverless apps heavily rely on messaging, and AWS services include queues, publish/subscribe, and event routing functionality. This article examines the key characteristics of SNS, SQS, and EventBridge as well as how each of them offers distinctive capabilities for your workloads.  

Do you still have questions? Great! Cos we would love to answer them. Learn more about decoupled architectures and messaging services best suited for your serverless application at Webuters.