Background : Due to quick development we have our servers in PHP and implementing services like Pusher and Socket.io is not an option.
So, we are planning on using AWS S3 bucket files and the data content, to update them and to poll them and see if there are new messages or not.
Would like to know how many requests/second can an S3 file or an S3 Bucket handle ?
You can make pretty much as many requests per second as you want, but beware your bill at the end of the month as you are charged per API call.
Further more, depending on the region you are using there may be no "read after write consistency", which could make your application unreliable.
Bottom line: can you do it? Yes. Do I recommend it? Considering your use case: no.