AWS SNS workaround for 100,000 topics limit

Question

I am developing an architecture for push notifications using AWS SNS with APNS and GCM. The model that I am following is

• Each user (not device) will have an SNS topic corresponding to it
• Each user can have multiple devices
• Create an platform application endpoint for each device
• Subscribe the platform application endpoint to the topic belonging to the device's user

This way, when we have to send a notification to all the devices of a user, we need to call the publish method using the user's topicArn and all its devices should get the message.

However, by default AWS has a limit of 100,000 topics. If we are anticipating higher number of users like 1 million or say 10 million to be optimistic, is there any workaround for this approach?

Should I ask AWS to raise the limit beforehand? Do they raise limit to a number like 100 million easily? Is there any cost implication of most of them are not used in the beginning few months?

Answer 1

disclosure: I used to work on Amazon SNS

The architecture you propose is a common pattern within Amazon SNS and is sound.

You should ask for a topic limit increase. There is no cost implication for having a higher topic limit, even if you create the topics and don't use them. However, you will pay $0.50/million requests for each CreateTopic call, with the first 1 million requests being free per month.

When you submit the support ticket, please document your use case. It helps the team expedite your limit increase request.

Answer 2

We followed a similar model to OP's with one exception - as the number of users grew, so did the number of dead accounts. Face it, user retention poses a challenge. So you may want to come up with a topic recycling strategy. Hint: Don't permanently bind a topic to a user but allow ARNs to expire, similar to a DHCP lease. Your app may periodically ask your web service what ARN it needs to subscribe to and expect to be re-assigned. If you build this into the client protocol early on, you won't need as many ARNs. After all, 100k active users is entirely different than 100k enrolled users :)

Answer 3

With Amazon SNS, there is no minimum fee and you pay only for what you use. Users pay $0.50 per 1 million Amazon SNS Requests, $0.06 per 100,000 Notification deliveries over HTTP, $0.75 per 100 Notification deliveries over SMS and $2.00 per 100,000 Notification deliveries over Email.

Amazon SNS also includes a Free Tier, where users can get started with Amazon SNS for free. Each month, Amazon SNS customers pay no charges for the first 1 million Amazon SNS Requests, no charges for the first 100,000 Notifications over HTTP, no charges for the first 100 Notifications over SMS and no charges for the first 1,000 Notifications over Email.

So I will suggest increase the limit before hand if that is anticipated by you. you don't get charged for increasing the limits. They will definitely increase to 100 Million.