How to handle disabled endpoint in SNS

Question

I'm using AWS SNS for send a push notification to mobile app by subscribe all the device under a single SNS Topic. Then to send notification I just send to that topic.However if some endpoint could not receive a message for whatever reason, SNS will mark that endpoint as disabled.

This could be good if SNS only mark a permanent invalid endpoint, but it's not. Since if I re-enable it, then after next push notification sent its might not back to disable again which mean in the next push it can receive a message properly.

The process to re-enable was quite pain, I have to schedule a batch process to loop all the endpoint under each SNS application and re-enable each device endpoint 1 by 1. This take hours and increasing as device number grow.

How can I know which endpoint was really no longer valid due to user already uninstall an app so I don't have to bother re-enable it? Or, is there any better way to handle this?

Answer 1

I believe the right solution of the problem is to stop the endpoints from getting disabled in the first place. The strategy should be such that SNS only disable the permanently invalid endpoints such as app uninstalled cases and avoid/recover from other cases.

I was in contact with the AWS support. I came to know about a case where the device token for a device can become invalid and in my case, I had a logic where I was re-enabling the endpoint of the device but using the same invalid token as before. Because of this the endpoint will become enabled but as soon as there is a push done to it, SNS will mark it disabled again since the underlying token is invalid. The right thing to do is to check if the token has changed or not from the device side and when it has pass the token for SNS registration again.

Below is the pseudo code for this strategy:

///////////////////////
retrieve the latest token from the mobile OS
if (endpoint arn not stored)
 # first time registration
 call CreatePlatformEndpoint
 store returned endpoint arn
endif

call GetEndpointAttributes on the endpoint arn

if (getting attributes encountered NotFound exception)
 #endpoint was deleted
 call CreatePlatformEndpoint
 store returned endpoint arn
else
 if (token in endpoint does not match latest) or
  (GetEndpointAttributes shows endpoint as disabled)
  call SetEndpointAttributes to set the
                     latest token and enable the endpoint
 endif
endif
//////////////////////