Android sync adapter by Anatoliy Kaverin

1. DEVELOPING ANDROID CLIENT
APPS VIA SYNCADAPTER
Anatoliy Kaverin
Lohika @ 2013

2. SESSION AGENDA
 Why?
 SyncAdapter!? LOLWUT?
 The big picture
 Puzzles
 Does anybody use it?
 Code samples, documentation
 Q&A
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3. IMAGINE…
SIMPLE CLIENT-SERVER APP
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4. SYNC CACHE: ISSUES TO CONSIDER
Are we done?
 Global Sync setting
 Bandwidth starvation
 YES, queued
 YES, even duplicates
 YES, even if app is off
 YES, built in support
Hand-made  SyncAdapter framework
 Network availability
 Pending queue
 Refresh on network
 Periodic update
 YES, manual override
 YES! YES! YES!
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5. SYNCADAPTER!? LOLWUT?
 Well, you probably use it everyday…
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6. THE BIG PICTURE – BASIC FLOW
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7. THE BIG PICTURE – PUZZLES
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8. PREREQUISITES TO CONSIDER
 Network layer separation
 Plain implementation
 Sync status field for synced entities
 Usually NOOP, Created, Updated & Deleted
 Consider the field in UI flows
 Consider partial sync
 For better performance to sync only local delta
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9. PUZZLES – ACCOUNT (1)
 Key Features
 Manage credentials;
 Safe system store;
 Multitenant support
 Sync related
 Token caching and invalidation
 Alternative flow to login or sign in
 Store extra data with account
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10. PUZZLES – ACCOUNT (2)
 Checklist:
 Implement Authenticator
 Implement Authentication Service
 Define configuration in XML
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11. PUZZLES – ACCOUNT (3)
 Checklist:
 Register Authentication Service in AndroidManifest
 Add permissions
 APIs to use:
 android.accounts.AccountManager to work with accounts
 android.accounts.Account to store credentials
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12. PUZZLES – CONTENT PROVIDER (1)
 Key features
 Heart of DAO
 Resource effective
 Cursor, resource-effective scalability
 Power of Joins
 Built-in ListView refresh via ContentObserver &
Cursor
 Sync related
 Acts as mediator for sync and UI layers
 Supports automatic delta upload sync
 NOTE: Can be fake one, but you’ll lose a lot of magic
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13. PUZZLES – CONTENT PROVIDER (2)
 Minimal implementation based on
https://github.com/novoda/SQLiteProvider
 Supports all CRUD
 Supports DB versioning
 And even more…
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14. PUZZLES – SYNCADAPTER (1)
 Key features
 Plugin to Android SyncManager
 SyncManager manages queue of execution
 Adapter is executed in background thread & when
network is available
 Sync related
 Scheduling & automated mode
 Respects system settings
 Can be overridden by manual request
 Partial sync supported
 Upload only local delta
 Any other criteria (Bundle) 14

15. PUZZLES – SYNCADAPTER (2)
 Checklist
 Implement SyncAdapter class
 Implement Sync Service
 Define configuration xml
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16. PUZZLES – SYNCADAPTER (3)
 Checklist
 Register Sync Service in AndroidManifest
 Add permissions
 APIs to use
 android.content.ContentResolver to reach SyncManager
programmatically
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17. PUZZLES – SYNCADAPTER (4)
 How to trigger sync?
 Upload delta
 ContentResolver.notifyChange
 Be aware of cyclic calls if used in ContentProvider
 Scheduling
 ContentResolver.addPeriodicSync
 Automated
 ContentResolver.setSyncAutomatically
 Manual
 ContentResolver.requestSync
 Manual forced
 ContentResolver.requestSync
 Pass SYNC_EXTRAS_MANUAL in bundle
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18. THE BIG PICTURE – OPTIONAL PUZZLES
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19. PROS & CONS
 Pros
 Simplify server interaction
 A lot of work handled by framework
 Resource effective – the Android way
 Cons
 A lot of puzzles, hard to start…
 Lack of documentation
 Error handling
 Bugs 
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20. DOESANYBODYUSEIT?
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21. DOCUMENTATION
 Official docs
 Great tutorial added in August ’13
http://developer.android.com/training/sync-
adapters/index.html + code sample
 Stackoverflow, use tags below
 [android-syncadapter]
 [sync] + [android]
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22. BONUS: CODE SAMPLES
 Repo on GitHub
https://github.com/springbyexample/spring-by-
example
 Toy client-server app (both parties supplied )
 Shows all puzzles implemented:
 Accounts – fake one, there is no authentication
 Content Provider based on novoda library
 SyncAdapter logics
 All wrapping XML configuration
 Built via Maven
 Follow README and be happy 
 Got questions?
 a.kaverin@gmail.com 22

23. Q & A
Thanks for your attention!23