AWS SNS

Amazon Simple Notification Service (SNS) is a managed messaging service for pub/sub communication, mobile push notifications, and SMS messaging.

Key Concepts

Concept	Description
Topic	A logical channel for messages
Publisher	Sends messages to topics
Subscriber	Receives messages from topics
Message	The content being sent
Subscription	Link between topic and endpoint

Topic Types

Type	Use Case	Features
Standard	High throughput	Best-effort ordering, at-least-once
FIFO	Ordered delivery	Strict ordering, exactly-once

Subscription Protocols

Protocol	Description	Use Case
`HTTP/HTTPS`	Webhook endpoints	API integrations
`Email/Email-JSON`	Email notifications	Human notifications
`SMS`	Text messages	Mobile alerts
`SQS`	Queue integration	Async processing
`Lambda`	Function trigger	Serverless processing
`Kinesis Firehose`	Data streaming	Analytics pipelines
`Application`	Mobile push	iOS/Android notifications

Standard vs FIFO Topics

Feature	Standard	FIFO
Throughput	Unlimited	300 msg/s (3000 with batching)
Ordering	Best-effort	Strict FIFO
Deduplication	No	Yes (5 minute window)
Message groups	No	Yes
Naming	Any name	Must end with `.fifo`

Message Filtering

Filter messages at subscription level:

{
  "eventType": ["order_created", "order_updated"],
  "store": [{"prefix": "store-"}],
  "price": [{"numeric": [">", 100]}],
  "customer": [{"exists": true}]
}

Filter Operators

Operator	Example
Exact match	`["value"]`
Prefix	`[{"prefix": "prod-"}]`
Suffix	`[{"suffix": "-v2"}]`
Numeric	`[{"numeric": [">=", 10, "<", 100]}]`
Exists	`[{"exists": true}]`
NOT	`[{"anything-but": ["ignore"]}]`
OR	`["a", "b", "c"]`

Message Attributes

Add metadata to messages:

await sns.publish({
  TopicArn: 'arn:aws:sns:us-east-1:123456789012:my-topic',
  Message: JSON.stringify({ orderId: '123' }),
  MessageAttributes: {
    eventType: {
      DataType: 'String',
      StringValue: 'order_created'
    },
    priority: {
      DataType: 'Number',
      StringValue: '1'
    }
  }
});

Lambda Integration

SNS can trigger Lambda functions:

export const handler = async (event) => {
  for (const record of event.Records) {
    const snsMessage = record.Sns;
    console.log('Subject:', snsMessage.Subject);
    console.log('Message:', snsMessage.Message);
    console.log('Attributes:', snsMessage.MessageAttributes);
    
    // Process message
    const data = JSON.parse(snsMessage.Message);
    await processMessage(data);
  }
  
  return { statusCode: 200 };
};

SQS Integration (Fan-out)

Distribute messages to multiple queues:

Mobile Push Notifications

Platform Applications

Platform	Service
iOS	APNs (Apple Push Notification service)
Android	FCM (Firebase Cloud Messaging)
Amazon	ADM (Amazon Device Messaging)

Setup Push Notifications

# Create platform application
aws sns create-platform-application \
  --name MyApp-iOS \
  --platform APNS \
  --attributes PlatformCredential=PRIVATE_KEY,PlatformPrincipal=CERT

# Create endpoint for device
aws sns create-platform-endpoint \
  --platform-application-arn arn:aws:sns:us-east-1:123456789012:app/APNS/MyApp-iOS \
  --token DEVICE_TOKEN

# Publish to device
aws sns publish \
  --target-arn arn:aws:sns:us-east-1:123456789012:endpoint/APNS/MyApp/abc123 \
  --message '{"APNS": "{\"aps\": {\"alert\": \"Hello!\"}}"}'

SMS Messaging

Send SMS

aws sns publish \
  --phone-number +12345678901 \
  --message "Your verification code is 123456"

SMS Attributes

aws sns set-sms-attributes \
  --attributes '{
    "DefaultSMSType": "Transactional",
    "DefaultSenderID": "MyApp",
    "MonthlySpendLimit": "100"
  }'

SMS Type	Use Case
Transactional	Critical, time-sensitive (OTP, alerts)
Promotional	Marketing, non-critical

Dead-Letter Queues

Handle failed deliveries:

aws sns set-subscription-attributes \
  --subscription-arn arn:aws:sns:us-east-1:123456789012:my-topic:abc123 \
  --attribute-name RedrivePolicy \
  --attribute-value '{
    "deadLetterTargetArn": "arn:aws:sqs:us-east-1:123456789012:my-dlq"
  }'

Delivery Status Logging

Log message delivery status to CloudWatch:

aws sns set-topic-attributes \
  --topic-arn arn:aws:sns:us-east-1:123456789012:my-topic \
  --attribute-name HTTPSuccessFeedbackRoleArn \
  --attribute-value arn:aws:iam::123456789012:role/SNSLoggingRole

aws sns set-topic-attributes \
  --topic-arn arn:aws:sns:us-east-1:123456789012:my-topic \
  --attribute-name HTTPFailureFeedbackRoleArn \
  --attribute-value arn:aws:iam::123456789012:role/SNSLoggingRole

Access Control

Topic Policy

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {"AWS": "arn:aws:iam::123456789012:role/MyRole"},
      "Action": "sns:Publish",
      "Resource": "arn:aws:sns:us-east-1:123456789012:my-topic"
    },
    {
      "Effect": "Allow",
      "Principal": {"Service": "s3.amazonaws.com"},
      "Action": "sns:Publish",
      "Resource": "arn:aws:sns:us-east-1:123456789012:my-topic",
      "Condition": {
        "ArnLike": {"aws:SourceArn": "arn:aws:s3:::my-bucket"}
      }
    }
  ]
}

Server-Side Encryption

aws sns create-topic \
  --name my-encrypted-topic \
  --attributes KmsMasterKeyId=alias/aws/sns

FIFO Topics

Create FIFO Topic

aws sns create-topic \
  --name my-topic.fifo \
  --attributes FifoTopic=true,ContentBasedDeduplication=true

Publish to FIFO

aws sns publish \
  --topic-arn arn:aws:sns:us-east-1:123456789012:my-topic.fifo \
  --message "Order 123 created" \
  --message-group-id "orders" \
  --message-deduplication-id "order-123-created"

Pricing

Type	Cost
Publish	$0.50 per million requests
HTTP/S delivery	$0.60 per million
SQS/Lambda	Free
SMS	Varies by country
Email	$2.00 per 100,000

Best Practices

Design

Use message filtering to reduce processing
Implement idempotent consumers
Use DLQs for failed messages
Enable delivery status logging

Security

Use topic policies for access control
Enable server-side encryption
Use VPC endpoints for private access
Validate message signatures

Performance

Use FIFO only when ordering is critical
Batch publishes when possible
Use message attributes for filtering
Monitor delivery metrics

Next Steps

SNS CLI Reference

Complete CLI commands

SQS

Simple Queue Service

SNS CLI Reference

SQS

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