All about AWS SNS: Simple Notification Service

All about AWS SNS: Simple Notification Service


6 min read

Introduction to AWS SNS

AWS SNS, or Amazon Simple Notification Service, is a fully managed messaging service provided by Amazon Web Services. It enables the sending and receiving of messages between various software components and distributed systems, as well as the delivery of messages to multiple recipients or subscribers. SNS supports a range of messaging protocols such as SMS, email, HTTP, and HTTPS, and can be integrated with other AWS services such as Amazon SQS, AWS Lambda, and AWS CloudFormation. SNS is a highly scalable and reliable service that provides publishers with the ability to send messages to large numbers of subscribers simultaneously, making it a popular choice for applications requiring high throughput, fanout, and real-time notifications.

SNS Architecture

The architecture of AWS SNS includes three main components: publishers, topics, and subscribers.

  1. Publishers: Publishers are the entities that generate messages and send them to the SNS topic. Publishers can be any AWS service, such as EC2 instances, Lambda functions, or any application running on-premises or on the cloud. Publishers can also be third-party applications or services.

  2. Topics: Topics are the channels through which messages are distributed to subscribers. Topics can be thought of as endpoints to which publishers send messages. Each topic has a unique Amazon Resource Name (ARN), which serves as a globally unique identifier.

  3. Subscribers: Subscribers are the entities that receive messages from the topics to which they have subscribed. Subscribers can be any endpoint that can receive messages, such as email addresses, SMS text messages, mobile push notifications, AWS Lambda functions, HTTP endpoints, or even other SNS topics.

SNS architecture is designed to be highly available, fault-tolerant, and scalable. When a publisher sends a message to a topic, the message is automatically distributed to all the subscribers who have subscribed to that topic. SNS supports multiple message delivery protocols, including HTTP, HTTPS, email, SMS, and mobile push notifications, which makes it flexible and versatile.

SNS Use Cases

  1. Notification services: SNS can be used as a notification service to send alerts, notifications, and updates to users, administrators, and applications. This can include system events, user activities, billing alerts, and more.

  2. Mobile push notifications: SNS can be used to deliver push notifications to mobile devices, including Android and iOS devices. This can be useful for sending personalized messages to users based on their preferences and activities.

  3. Fan-out scenarios: SNS can be used to fan-out messages to multiple subscribers in parallel. For example, if you have multiple subscribers to a topic, SNS can distribute the message to all subscribers at the same time.

  4. Event-driven architectures: SNS can be used to build event-driven architectures where multiple services can subscribe to events and act on them. This can include Lambda functions, EC2 instances, and other AWS services.

  5. SMS messaging: SNS can be used to send SMS messages to mobile devices. This can be useful for sending messages to users who don't have a smartphone or mobile data connection.

  6. Email notifications: SNS can be used to send email notifications to users or administrators. This can include system alerts, billing alerts, and more.

  7. IoT applications: SNS can be used to send notifications to IoT devices, including sensors and other connected devices. This can be useful for real-time monitoring and control of IoT applications.

Creating an SNS Topic

  1. Open the Amazon SNS console.

  2. Click on the "Create topic" button.

  3. Enter a name for the topic and an optional display name.

  4. Select a delivery protocol for the messages that will be sent to this topic. You can choose from various protocols like HTTP, HTTPS, email, SMS, Lambda function, mobile push notification, etc.

  5. Click on the "Create topic" button to create the topic.

Once the topic is created, you can add subscribers to it who will receive the messages that are published to this topic.

Adding Subscribers

After creating a topic, the next step is to add subscribers who will receive messages from the topic. SNS supports several types of subscribers, including:

  1. Email endpoints: Email addresses that will receive messages in their email inbox.

  2. SMS endpoints: Mobile phone numbers that will receive text messages.

  3. HTTP/HTTPS endpoints: Web servers that will receive messages via HTTP/HTTPS protocols.

  4. Lambda functions: AWS Lambda functions that will be triggered by messages sent to the topic.

  5. Mobile push endpoints: Endpoints for mobile devices that will receive push notifications.

To add a subscriber to a topic, you first need to create a subscription. When you create a subscription, SNS sends a confirmation message to the endpoint that you specified. The endpoint must confirm the subscription request by sending a confirmation message back to SNS.

Once the subscription is confirmed, the endpoint is added as a subscriber to the topic. You can add multiple subscribers to a topic, and each subscriber can have a different endpoint type.

Publishing Messages

Once you have created a topic and subscribed the endpoints, the next step is to publish messages to the topic. This can be done in several ways:

  1. AWS Management Console: Go to the SNS service page, select the topic you want to publish the message to, and click on the "Publish message" button. Type the message you want to send and click on "Publish".

  2. AWS SDKs: You can use the AWS SDKs to publish messages to the SNS topic. You need to first configure the SDK with your AWS credentials and then use the appropriate SDK method to publish messages.

  3. AWS CLI: The AWS CLI provides a simple command-line interface to publish messages to SNS topics. You can use the aws sns publish command to publish a message. You need to specify the topic ARN and the message text.

  4. HTTP/HTTPS APIs: SNS also provides HTTP/HTTPS APIs to publish messages. You can use the POST method to publish a message. You need to specify the topic ARN, the message text, and the message attributes in the request body.

Once the message is published to the topic, SNS will deliver the message to all the subscribed endpoints for that topic.

Monitoring and Logging

AWS SNS provides several monitoring and logging features to help you track the performance and health of your SNS topics and messages.

  1. CloudWatch Metrics: SNS publishes several metrics to Amazon CloudWatch, such as the number of messages published, the number of messages delivered, and the number of messages rejected. These metrics can be used to create alarms, set up automatic scaling, and troubleshoot issues.

  2. CloudTrail: SNS is integrated with AWS CloudTrail, which provides a history of API calls made to the service. This can be used for auditing and compliance purposes, as well as troubleshooting issues.

  3. SNS Delivery Status: SNS also provides delivery status for messages, which includes information such as the message ID, the destination ARN, the status of the delivery, and the timestamp of the delivery.

  4. SNS Mobile Push: If you're using SNS to send push notifications to mobile devices, you can use the SNS Mobile Push console to monitor the number of messages sent, the number of messages delivered, and the number of errors.

  5. SNS Delivery Logs: SNS also provides delivery logs, which include detailed information about each delivery attempt, such as the message ID, the destination ARN, the status of the delivery, and the reason for any failures. These logs can be used for debugging and troubleshooting purposes.


AWS SNS is a highly versatile and scalable messaging service that can be used for a variety of use cases, such as sending notifications, alerts, and updates to users and applications. Its architecture is based on topics and subscribers, which allows for flexible message routing and filtering. Additionally, it provides robust monitoring and logging capabilities to ensure reliable message delivery. Overall, AWS SNS is a powerful tool for building modern, event-driven architectures that can handle large volumes of messages and users.

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