File Sync. One of the most talked about and underestimated integration patterns.

Here is a little checklist of questions to answer before you start building.

• What systems are we syncing?
• Which system is your single source of truth?
• One time or ongoing?
• What is the scope of the sync (which folders, subfolders and file types)?
• What is the scale (how many and how large folders, subfolders and files)?
• How close to a real-time sync does it need to get?
• Which direction (one way, two way, partial — e.g. metadata only)?
• If both sides change one file, who wins?
• Which events (create, update, delete, move)?
• What does "update" mean (new full version, file replaced without versioning, both files remain but are name-versioned)?
• How should user permissions be handled?

(Would you add another one?)

When these get answered, then we know if we are building a kite, or a rocket ship.