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Stage 6 of 7 · Change it

Dropbox-Style File Sync Service: Sharing is an authorization check on every path

A file can be reached through a namespace path, a version manifest and many content blocks. Removing a user from the shared folder must not leave a permanent capability to keep downloading those blocks.

System so far· 3 parts
12CLIENTDesktop andmobile clientsDATABASEMetadatadatabaseSERVICEChange notifier

Select a component to see what it is responsible for and which state it owns.

  1. 1Metadata database → Change notifier: Journal advanced
  2. 2Change notifier → Desktop and mobile clients: Wake, then page from cursor
  • Asynchronous
  • Server push

What you need to know

0 of 1 checks done

  1. Check authorization at the metadata operation and at block retrieval. A signed URL is a bearer capability: anyone who has it can use it until it expires. Short lifetimes reduce revocation delay; proxying reads through an authorization service gives faster revocation but adds bandwidth, cost and a dependency on the hot path.

  2. Check

    The requirement says revocation takes effect within one minute. What must be true of cached download grants?