What is the best solution to multipart upload video to Amazon S3 by using realm app service

i try to use realm’s http endpoint and functions to do multipart upload video to AWS S3. there are few problems i have, hope somebody can suggest a better solution if using function feature is not possible to do it.

multipart upload to AWS S3 include three step
initializeMultipartUpload ()

  1. how to do this kind of sequential request by using realm functions, and they all share the same S3 instance.
  2. function only support JSON or EJSON format, it will not work for raw content response when loading videos
  3. in nodejs, express setting, we can use ‘body parser’ and ‘cors’ package as helper, how to do it if using realm function by itself.