Amazon nodejs Aws-Sdk S3 signedUrl “callback”

Question

At the moment, I develop a little image-uploader for my nodejs-webapp. Every user has the right to upload 10 images(for example).

The upload should be performed on the client side to reduce the server workload.

For this reason, I generate a signed url on the server-side and send it to the client:

let request:S3.PutObjectRequest = {
   Key:filename,
   Bucket: "image-proxy",
   Expires:new Date(20000),
   ContentType:"jpg",ACL:"public-read" 
}
this.s3.getSignedUrl("putObject",request,cb);

This works well, but how can I control the max of 10 Images and the general status of the upload? One possibility would be to send a callback from the client to the server, after the upload is completed.

But "never trust the client", what if a "hacker" block this callback.

Is it possible, to get a callback server-side from the "putObject", after the upload is finished?

Thanks.

Answer 1

Micheal had the solution:

AmazonS3 NotificationHowTo