Store results in S3
I need to generate images from HTML then store the resulting image in S3 while the user is waiting. To do this with the Batch API I'd have to make the request, poll for it to finish, pull the image and send it to S3 then let the user know it's done. If I could have the service store the image in S3 I could just poll for the S3 URL until it has a 200.
This can also be done simpler with single page requests, but I may need to do a lot of these and it seems you'd prefer the batch API. With the single page request I can call the API, wait for the response, download the image, then push to S3, then return to the user. That's still a complicated process though.