• Filesystem that just works
• “The magic folder”
Then
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• Multi-device world
• Apps
• Mobile storage and sync
Now
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• Cross-platform support
• Store data
• User auth and permissions
• Sync across devices
• Offline access
Mobile backend challenges
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Write your own backend API
Solution
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Mobile backend service
(Parse, iCloud, Dropbox, etc.)
Solution
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Dropbox for your mobile apps
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Store data in user’s own Dropbox
• Free for developers
• Access to files outside your app
• User owns their data
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How can I use Dropbox in my app?
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Core API
• REST-ish, OAuth 2.0, JSON
• Android, iOS, OS X, Python,
Ruby, Java, PHP
• Community-supported libraries
for C#, JavaScript, Perl, etc.
HTTP API for files
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• List files
/metadata//
• Upload file
/files_put//
• Get a thumbnail
/thumbnails//
• Share via a link
/shares//
Core API
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Authentication and permissions
• Connect with Dropbox
• Full or limited access
• Only request permissions that
your app needs
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Permissions
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Permissions
App folder
Permission to a specific folder
!
File types
Permission to a class of files (e.g. images)
!
Full Dropbox
Permission to everything
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Core API is great. So what now?
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Sync across devices
• Files available everywhere
• Syncs across devices
• Offline access
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Sync API
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Sync API (like Core API)
• Files for your app in your user’s Dropbox
• Store and sync photos, videos, files, etc.
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• Handles offline caching and syncing
• Notifications of changes
Sync API
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Image Grid Sample
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No content
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Image Grid Sample code
iOS
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Initialize the filesystem
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Listen for changes
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Display thumbnail
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Great for files… but what about data?
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Sync API
file system-like interface
Datastore API
structured data
Mobile APIs
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Bundled together for Android, iOS, OS X
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Datastore API
• Storage for structured data
• Like a NoSQL database
• Stored in the user’s Dropbox
• Not files!
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account→datastore→table→record→field→value
Datastore API
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Why not files?
Monolithic → inefficient syncing
Opaque → conflicts
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Why not files?
• Clearly defined structure
• More efficient syncing
• Advanced conflict resolution
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Similar to Sync API …
• Handles offline caching and syncing
• Notifications of changes
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Click the Box
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No content
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Click the Box code
JavaScript
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Initialize datastore
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Click listener
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Listen for changes
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Display level
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Take it offline!
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No content
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• Local changes cached when offline
• Syncs changes with server when online
• Automatically merge changes
Offline / online syncing
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• List of changes - “delta”
• Client sends delta with “parent revision”
on sync
• Server rejects a delta if parent revision
doesn’t match
• Server sends list of deltas to catch up
• Client resolves conflict, sends new delta
Conflict resolution
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Device A
Server
Device B
Visually
2
r: 2
2
r: 2
2
r: 2
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Device A
Server
Device B
Visually
2
r: 2
2
r: 2
2
r: 2
2
r: 2
2
r: 2
3
r: 2
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Device A
Server
Device B
Visually
2
r: 2
2
r: 2
2
r: 2
3
r: 3
3
r: 3
2
r: 2
2
r: 2
3
r: 2
• Server rejects delta
• Server sends delta to catch up
• Client resolves conflict
• Client sends new delta
• Server accepts new delta
Conflict resolution
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• Changes to different records commute
• Deletions win
• Changes to the same field are merged
Conflict resolution rules
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Customizable per-field:
• Remote (default) - server wins
• Local - client wins
• Max - greater value wins
• Min - lesser value wins
• Sum - adds differences together
Conflict resolution
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Custom resolution rule
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Powerful stuff…
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• Cross-platform SDKs
• Both files and data
• Users’ own Dropbox
• Handles offline access, sync,
and conflict resolution
Sync and Datastore APIs