This document provides an overview of developing Android client apps using SyncAdapter. It discusses the key components involved - Account, ContentProvider, and SyncAdapter. It outlines the basic workflow and issues to consider with sync caching. Puzzles involved with implementing each component are described, along with code samples and documentation resources. Pros and cons of the SyncAdapter framework are presented.

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
2

3. IMAGINE…
SIMPLE CLIENT-SERVER APP
3

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!
4

5. SYNCADAPTER!? LOLWUT?
 Well, you probably use it everyday…
5

6. THE BIG PICTURE – BASIC FLOW
6

7. THE BIG PICTURE – PUZZLES
7

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
8

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
9

10. PUZZLES – ACCOUNT (2)
 Checklist:
 Implement Authenticator
 Implement Authentication Service
 Define configuration in XML
10

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
11

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
 12

13. PUZZLES – CONTENT PROVIDER (2)
 Minimal implementation based on
https://github.com/novoda/SQLiteProvider
 Supports all CRUD
 Supports DB versioning
 And even more…
13

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
15

16. PUZZLES – SYNCADAPTER (3)
 Checklist
 Register Sync Service in AndroidManifest
 Add permissions
 APIs to use
 android.content.ContentResolver to reach SyncManager
programmatically
16

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
17

18. THE BIG PICTURE – OPTIONAL PUZZLES
18

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 
19

20. DOESANYBODYUSEIT?
20

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]
21

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