Signed URL
A signed URL is a URL that encodes a short-lived authorisation (who can read the file, and for how long) in its query string. Private files in cloud storage are not publicly readable; the server generates a signed URL on demand when a specific viewer is allowed to see the file.
Syndik8 uses signed URLs in two places:
- Usage-log photos. When a viewer opens a booking and is entitled to see the photo, the app generates a URL that is valid for 15 minutes.
- Documents. Every fetch from the document viewer or Share action (every document, every time) is via a fresh signed URL, also valid for 15 minutes.
After the window the URL stops working. The signed URL cannot usefully be shared because it expires too fast, which is the point. If a viewer is not entitled to see the file, no URL is generated at all.