I am trying to create an iOS app, which will transfer the files from an iPhone to a server, process them there, and return the result to the app instantly.
I have noticed that AWS offers an SDK to transfer files from iOS app to S3, but not to EC2 (or at least to EBS which can be attached to EC2). I wonder why I have to go through S3, when my business logic doesn't warrant storage of files. I have used file system softwares such as s3cmd and s3fs to connect to S3 from EC2, but they are very slow at transferring files to EC2. I am concerned that the route through S3 will kill time, especially when the users expect result in a split second.
Could you please guide me on how can I bypass the S3 route to transfer files in real time from iOS app to EC2 (or EBS)?
Allowing an app to write directly to an instance file system is a non starter, short of treating it as a network drive which would be pretty convoluted, not to mention the security issues youll almost certainly have. This really is what s3 is there for. You say you are seeing bad performance between ec2 and s3, this does not sound at all right, this will be an internal datacenter connection which would be at the very least several orders of magnitude faster than a connection from a mobile device to the amazon datacentre. Are you sure you created your bucket and instance in the same region? Alternatively it might be the clients you're using, dont try and setup file system access, just use the aws cli.
If you are really tied to the idea of going direct to the ec2 instance you will need to do it via some network connection, either by running a web server or perhaps using some variety of copy over ssh if that is available on ios. It does seem pointless to set this up when s3 has already done it for you. Finally depending on how big the files are you may be able to get away with sqs or some kind of database store.