title: Allow full synchronized filesystem read/write access over a subdirectory of an S3 bucket?
body: <p>I have a web service involving the attachment of multiple documents to one of many "objects". To simplify this process and make it easier to edit each file individually if the user so desires, I want the user to be able to synchronise all of these files onto a directory on his/her computer (much like that of Google Drive or Dropbox). If the user were to change one of these files, remove a file, or add a file, this would reflect on my web service, and hence affect the files that are attached to this "object".</p>
  
  <p>What would be the best choice of services to do this? I am currently using a Node.JS back-end, although I suspect this will do little to influence the choice of storage. I'm looking for a service that allows the user the flexibility of full filesystem-level CRUD, whilst synchronising the files in a secure manner to a subset of a larger object storage collection, much like synchronising (and only providing access to) a subdirectory of an AWS S3 bucket, hence the title of this question.</p>
  
  <p>I'm currently looking into (somehow) doing this with AWS S3, although I am open to using another storage service.</p>
  
  <p>Thanks in advance.</p>