Hi there! As an experienced cloud architect, I help companies build sophisticated messaging platforms on AWS. In this comprehensive guide, I‘ll explain everything you need to know about using Amazon Simple Notification Service (SNS) for your application integration and communication needs.
What is Amazon SNS?
Amazon SNS handles all the heavy lifting around queuing, routing, delivery, and retries for publishing messages across services, apps, and end users. Some examples include:
- Sending account registration emails to new customers
- Pushing firmware updates to IoT devices
- Broadcasting price change alerts to retailer apps
- Streaming clicks, codes, and events to data lakes and analytics tools
In other words, SNS takes care of the undifferentiated messiness of messaging so you can focus on your core apps.
Key Capabilities:
|
Now let‘s dig into these key capabilities and features in more detail…
SNS Publishing and Subscribing
SNS uses a publish/subscribe model for sending and receiving messages.
There are two main players:
Publishers – The senders who publish messages to SNS topics. This allows fanning out messages to many recipients.
Subscribers – The receivers who subscribe to topics and consume messages. Subscribers opt-in to receive messages.
This diagram shows the path a message takes:
[SNS architecture diagram]Decoupling publishers from subscribers provides flexibility to evolve consumers without impacting producers.
Comparing SNS Topic Types
SNS supports two types of topics for sending messages:
| Topic Type | Standard | FIFO |
| Ordering | Best effort | Strict order |
| Deduplication | No | Yes |
| Throughput | Unlimited | 300 msg/sec |
| Use Case | High volume broadcasting | Precise sequencing |
As this table shows, Standard topics focus on maximizing throughput while FIFO topics preserve sequencing and prevent duplicates.
Reliability
Messaging is useless if it‘s not reliable. Fortunately, SNS provides durable message storage across multiple Availability Zones. Messages are persisted redundantly to prevent data loss.
SNS leverages automatic scaling capabilities to handle spikes in throughput without delays or timeouts. Geographic replication is also available for disaster recovery needs.
With compute, storage, and networking separated:
[SNS reliability diagram]SNS ensures messages are delivered unless subscribers actively reject them or explicitly filter them out.
Securing SNS Topics
While performance matters, security is also a priority. SNS encrypts messages via HTTPS by default using TLS across public endpoints.
For private connectivity, SNS endpoints can be created inside your VPC keeping data within your virtual network. VPC endpoints connect over your internal IP addressing without an internet gateway.
[SNS VPC endpoint diagram]AWS Key Management Service (KMS) adds another layer of protection with client-side data encryption capabilities too.
Granular access policies can limit access through IAM roles, access control lists, and data encryption policies. Logging and auditing provides visibility into how your data is being accessed.
Application-to-Person vs App-to-App Messaging
There are two primary use cases and topologies for SNS…
A2P – Application-to-person messaging transmits messages to end users at scale via SMS, push, email. This allows broadcasting alerts or promotions to customers.
A2A – Application-to-application messaging enables decoupled integration between distributed services. This allows different apps to respond to events triggered by others.
| Direction | A2P | A2A |
| Communication | App to User | App to App |
| Protocols | SMS, push, email | MQTT, HTTP/S |
| Use Cases | – Account updates – Appointment reminders – Promotional alerts |
– Microservices integration – Event streaming – Data pipeline triggers |
Understanding these two messaging patterns helps direct appropriate SNS topic and subscriber selection.
Now let‘s look at some alternatives…
Alternatives to Amazon SNS
The two most widely-adopted alternatives to consider beyond SNS are:
Azure Service Bus – Microsoft‘s mature and fully-managed messaging service with AMQP/HTTP support. Integrates smoothly across Azure ecosystem.
Google Cloud Pub/Sub – Google‘s globally distributed real-time messaging backed by the same infrastructure Google uses internally.
I‘ve compared the capabilities of each service below:
| SNS | Azure Service Bus | GCP Pub/Sub | |
| Protocols | HTTPS, SMS, Email, SQS | AMQP, MQTT, HTTP/S | HTTP/S |
| Ordering | Both FIFO and standard | First-in-first-out queues | Publisher defines |
| Security | Encryption in transit and at rest | Azure role-based access | Encryption in transit and at rest |
| Pricing | Pay as you go | Pay as you go | Committed usage discounts |
AWS and Azure offer the most mature capabilities given their long history in the space. But Google is catching up quickly.
Ultimately the best fit depends on your specific protocols, workload patterns, security needs and existing cloud investments.
Getting Started Step-by-Step
Here is how to start using SNS in 6 easy steps:
- Sign-up – Create an AWS account if you don‘t already have one
- Create SNS topic – Topics represent communication channels to publish messages
- Create subscriptions – Decide which app or queue will receive messages
- Write publishing app – Write your publisher app to create and push messages
- Write consumer app – Write your consumer app to ingest and process messages
- Publish messages – Send messages and watch them get consumed!
Once you have these basics built, you can start designing more complex, large-scale publish/subscribe architectures.
Advanced Tips for SNS
Here are some more advanced tips for squeezing the most performance, cost savings, and reliability from Amazon SNS:
Message Filtering – Restrict messages to relevant subscribers using filters
Message Batching – Group messages together to optimize throughput and costs
Message Attributes – Categorize messages using attributes for easier processing
Dead-Letter Queues – Capture unprocessed messages for debugging and reprocessing
ASAP Delivery – Prioritize urgent messages to be delivered instantly with high priority
Instance Sizing – Right size SNS topic capacity for cost efficiency
Retention Policies – Set retention duration to balance compliance vs costs
Alarms – Monitor usage metrics and set alarms for overages or anomalies
Estimating SNS Costs
One major advantage of SNS is the affordable pay-as-you-go pricing model. There are no minimum fees or upfront commitments to use it.
You only pay for what you use each month. Here is an overview of the pricing dimensions:
| SNS Usage Metric | Price Per Unit |
| Requests to publish messages | $0.50 per 1 million requests |
| Notification deliveries over HTTP/S | $0.06 per 100,000 deliveries |
| Notification deliveries over SMS | $0.75 per 100 deliveries |
Let‘s calculate a sample SNS bill given 10 million HTTP notification deliveries and 50 SMS messages per month:
- 10M HTTP notifications = $6 per month
- 50 SMS messages = $0.38 per month
- Total = $6.38 per month
As you can see, costs remain reasonable for most typical workloads. But scale equates to higher spend overall.
Now let‘s recap some key pros and cons of SNS…
The Pros and Cons of Amazon SNS
Pros:
- Smooth publish/subscribe capabilities
- Handles security, scalability out of the box
- Cost efficient "pay as you go" model
- Integrates well across AWS
- Flexible support for many protocols
- Durable and reliable delivery
Cons:
- Can get pricey for extremely high usage
- Potential vendor lock-in
- FIFO ordering limitations
- Steep learning curve when extending capabilities
For most integration and messaging use cases, Amazon SNS provides an appealing blend of convenience and sophistication.
The History of Amazon SNS
Amazon launched SNS over 12 years ago in 2010 alongside S3 and other foundational AWS building blocks.
Key milestones:
- 2010 – Amazon SNS launched
- 2012 – Topic subscriptions introduced
- 2014 – Mobile push notification support
- 2017 – SMS message support
- 2021 – FIFO ordering support
Expect Amazon to continue expanding and evolving SNS for years given long-term strategic nature of messaging workloads.
Conclusion and Next Steps
In summary, SNS solves the undifferentiated heavy lifting required for publishing and integrating messages across applications reliably and at scale.
Now that you have a comprehensive overview of SNS capabilities, features, messaging architectures, pricing, and more – you have the knowledge needed to get started.
As next steps, I recommend:
- Review the getting started guide hands-on
- Build sample publisher and subscriber apps
- Analyze your integration requirements
- Model an SNS topology for your workloads
Within an afternoon you can have SNS up and running. Then the real fun begins building production-grade messaging flows across your ecosystem.
I hope this detailed guide provides the perfect starting point for your messaging needs. Don‘t hesitate to reach out if any other questions come up!
