Upload a remote file without downloading first

Question

Our company has some Old Legacy Online Inventory Management systems (OLOIMs) where we have to individually upload thousands of PDFs to specific service tickets each day. The only way to get the files into the OLOIMs right now is to click the "Upload" button, then the "Open" box appears and you select the PDF on your computer to upload that corresponds to that service ticket. All of these PDFs are stored in an online storage location (Google Drive right now, but we could use any online storage). Right now, we download or sync all of these files locally before uploading them, which takes a long time. Is there a way to upload the file directly from the online storage, so it goes straight from the online storage to the OLOIM server without routing through my computer, using that upload button? We can't change anything on the OLOIM server, so we have to use that "Upload" button, but we can change all the other parts of the process before that point.

I tried copying the link to download the file from Google Drive and pasting this into the "Open" window as the filename. This kind of worked in that the file appeared on the OLOIM server successfully, but it downloaded to a temporary folder on my computer first. I would like to find a way to avoid having to download it to my computer first, and just go straight from the online storage to the OLOIM server. Again, we don't have to use Google Drive for the online storage, we can use anything.

We also considered copying the links to the files stored on Google Drive and just posting these on the server, instead of attaching them on the server, but then we have access and permissions problems. We don't want the links to be public, but everyone who can access the server needs to access these files, but not everyone who can access the server can also access the Google Drive folder, and it isn't feasible to give them all permission to access the Google Drive folder because there are hundreds or thousands of these users who have access.

Other things we have considered:

1. Set up a server that has all of the files on it, and have everyone who needs to attach files start a session on this server, open a browser window, and upload the files. The drawbacks are that we then have to maintain a server, which is Hard.
2. Find some kind of browser extension or program that makes the remote files appear local, and cleverly re-routes the upload request to the remote file server. It seems like this would break SSH or TLS or something.
3. Build a better system to replace the OLOIMs. We're working on it, but we need an interim solution if it exists.
4. Figure out what sort of command the Upload button sends to the OLOIM, and figure out how to re-create this in Google Apps Script so they can just open Google Drive online and click some button that will post the file to the server. Unfortunately, I'm not clever enough to figure out how to do this.

Answer 1

It is possible your OLOIM is using a basic HTML file upload, which means the upload is entirely up to your browser implementation and your browser will only know how to upload from a logical drive. No matter what you do with Google, that will mean the files go to your workstation first.

To your point 4, it seems like a decent solution. You would emulate your browser's interface to the OLOIM in your Google Apps Script and go direct to your OLOIM that way. It is not too hard to figure out what your browser is sending to/from your OLOIM using a tool like WireShark or Fiddler. You will need some one skilled enough to interpret the HTTP messages exchanged and implement the same with Google Apps Script.