The document discusses sync functionality in Android applications. It covers key components of the sync architecture like AccountManager, SyncManager, ContentProvider and SyncAdapter. It explains how these components work together to allow syncing of data between a device and server, both for uploading and downloading of data. It also discusses some common issues developers face around sync implementation, like handling IDs and deleting accounts. It provides best practices for making the sync implementation robust, like being lenient on data fetching but strict on uploading, and including resync functionality in the initial version.

1. Sync ON ANDROID
Jerzy Chalupski
chalup
jerzy@futuresimple.com

2. What we do in general...

3. What we do ALL THE TIME
sync, sync, sync, sync

4. Sync ON ANDROID
OVERVIEW ARCHITECTURE
CONTENT PROVIDER PITFALLS & PROTIPS

5. Sync ON ANDROID
OVERVIEW ARCHITECTURE
CONTENT PROVIDER PITFALLS & PROTIPS

6. Not exactly the fresh topic...
„Developing Android REST client
applications”
by Virgil Dobjanschi
@Google I/O 2010

7. Not exactly the fresh topic...
„Synchronizacja danych z serwisami
webowymi w Androidzie”
by Bartosz Filipowicz
@KrakDroid 2011

8. Not exactly the fresh topic...
„Synchronizacja danych z serwisami
webowymi w Androidzie”
by Bartosz Filipowicz
@KrakDroid 2011
...but there is still much confusion

9. AccountManager
SyncManager
UI Authenticator
ContentProvider
SyncAdapter
ContentResolver

10. „Wat? Why do I need to write
all this crap, sync is just
fetching data from server”
typical reaction

11. Sync provides data sharing

12. Sync provides data sharing
offline mode

13. Sync provides data sharing
offline mode
responsive UI

14. Sync provides data sharing
offline mode
responsive UI
GREAT UX

15. Sync ON ANDROID
OVERVIEW ARCHITECTURE
CONTENT PROVIDER PITFALLS & PROTIPS

16. ContentProvider 101: CRUD
CREATE insert()
READ query()
UPDATE update()
DELETE delete()

17. ContentProvider 101: URI
content://com.futuresimple.krakdroid.Provider/datasets/1

18. ContentProvider 101: URI
content://com.futuresimple.krakdroid.Provider/datasets/1

19. ContentProvider 101: URI
content://com.futuresimple.krakdroid.Provider/datasets/1

20. ContentProvider 101: URI
content://com.futuresimple.krakdroid.Provider/datasets/1

21. ContentProvider 101: notifications
content://com.futuresimple.krakdroid.Provider/datasets/1
content://com.futuresimple.krakdroid.Provider/solutions
content://com.futuresimple.krakdroid.Provider/solutions/1
content://com.futuresimple.krakdroid.Provider/solutions/1/answers/1
content://com.futuresimple.krakdroid.Provider/solutions/1/answers/2
content://com.futuresimple.krakdroid.Provider/solutions/2/answers/1

22. ContentProvider 101: notifications
content://com.futuresimple.krakdroid.Provider/datasets/1
content://com.futuresimple.krakdroid.Provider/solutions
content://com.futuresimple.krakdroid.Provider/solutions/1
content://com.futuresimple.krakdroid.Provider/solutions/1/answers/1
content://com.futuresimple.krakdroid.Provider/solutions/1/answers/2
content://com.futuresimple.krakdroid.Provider/solutions/2/answers/1
ContentResolver.notifyChange(“content://
com.futuresimple.krakdroid.Provider/datasets/1”);

23. ContentProvider 101: notifications
content://com.futuresimple.krakdroid.Provider/datasets/1
content://com.futuresimple.krakdroid.Provider/solutions
content://com.futuresimple.krakdroid.Provider/solutions/1
content://com.futuresimple.krakdroid.Provider/solutions/1/answers/1
content://com.futuresimple.krakdroid.Provider/solutions/1/answers/2
content://com.futuresimple.krakdroid.Provider/solutions/2/answers/1
ContentResolver.notifyChange(“content://
com.futuresimple.krakdroid.Provider/solutions/1/answers/1”);

24. Sync ON ANDROID
OVERVIEW ARCHITECTURE
CONTENT PROVIDER PITFALLS & PROTIPS

25. AccountManager
SyncManager
UI Authenticator
ContentProvider
SyncAdapter
ContentResolver

26. Authenticator Sync architecture
CREATING NEW ACCOUNT
AccountManager
addAccount()
UI
SyncManager ContentResolver
SyncAdapter ContentProvider

27. Authenticator Sync architecture
CREATING NEW ACCOUNT
addAccount()
AccountManager
addAccount()
UI
SyncManager ContentResolver
SyncAdapter ContentProvider

28. Authenticator Sync architecture
CREATING NEW ACCOUNT
addAccount()
AccountManager
addAccount()
UI
SyncManager ContentResolver
SyncAdapter ContentProvider

29. Authenticator Sync architecture
SHOW SYNCED DATA
AccountManager
UI
query()
SyncManager ContentResolver
query()
SyncAdapter ContentProvider

30. Authenticator Sync architecture
REQUEST SYNC
AccountManager
getAccountsByType()
UI
SyncManager ContentResolver
SyncAdapter ContentProvider

31. Authenticator Sync architecture
REQUEST SYNC
AccountManager
getAccountsByType()
UI requestSync()
SyncManager ContentResolver
SyncAdapter ContentProvider

32. Authenticator Sync architecture
REQUEST SYNC
AccountManager
getAccountsByType()
UI requestSync()
SyncManager ContentResolver
onPerformSync()
SyncAdapter ContentProvider

33. Authenticator Sync architecture
EDIT DATA
AccountManager
UI insert()
SyncManager ContentResolver
insert()
SyncAdapter ContentProvider

34. Authenticator Sync architecture
EDIT DATA
AccountManager
UI insert()
SyncManager ContentResolver
notifyChange() insert()
SyncAdapter ContentProvider

35. Authenticator Sync architecture
EDIT DATA
AccountManager
UI insert()
SyncManager ContentResolver
notifyChange() insert()
SyncAdapter ContentProvider

36. Authenticator Sync architecture
EDIT DATA
AccountManager
getAccountsByType()
UI insert()
SyncManager ContentResolver
notifyChange() insert()
SyncAdapter ContentProvider

37. Authenticator Sync architecture
EDIT DATA
AccountManager
getAccountsByType()
UI insert()
SyncManager ContentResolver
onPerformSync() notifyChange() insert()
SyncAdapter ContentProvider

38. Authenticator Sync architecture
POST NEW DATA
AccountManager
UI
SyncManager ContentResolver
onPerformSync()
SyncAdapter ContentProvider

39. Authenticator Sync architecture
POST NEW DATA
getAuthToken()
AccountManager
UI
SyncManager ContentResolver
onPerformSync()
SyncAdapter ContentProvider

40. Authenticator Sync architecture
POST NEW DATA
getAuthToken()
AccountManager
UI
SyncManager ContentResolver
query()
onPerformSync() query()
SyncAdapter ContentProvider

41. Authenticator Sync architecture
POST NEW DATA
getAuthToken()
AccountManager
UI
SyncManager ContentResolver
query()
onPerformSync() query()
SyncAdapter POST
ContentProvider

42. Authenticator Sync architecture
GET NEW DATA
AccountManager
UI
SyncManager ContentResolver
onPerformSync()
SyncAdapter ContentProvider

43. Authenticator Sync architecture
GET NEW DATA
getAuthToken()
AccountManager
UI
SyncManager ContentResolver
onPerformSync()
SyncAdapter ContentProvider

44. Authenticator Sync architecture
GET NEW DATA
getAuthToken()
AccountManager
UI
SyncManager ContentResolver
onPerformSync()
SyncAdapter GET
ContentProvider

45. Authenticator Sync architecture
GET NEW DATA
getAuthToken()
AccountManager
UI
SyncManager ContentResolver
applyBatch()
onPerformSync()
applyBatch()
SyncAdapter GET
ContentProvider

46. Authenticator Sync architecture
GET NEW DATA
getAuthToken()
AccountManager
UI
SyncManager ContentResolver
applyBatch()
onPerformSync() notifyChange()
applyBatch()
SyncAdapter GET
ContentProvider

47. Authenticator Sync architecture
GET NEW DATA
getAuthToken()
AccountManager
onLoaderFinished()
UI
SyncManager ContentResolver
applyBatch()
onPerformSync() notifyChange()
applyBatch()
SyncAdapter GET
ContentProvider

48. Authenticator Sync architecture
WIN #1: NO REMOTE I/O IN UI
AccountManager
UI
SyncManager ContentResolver
SyncAdapter ContentProvider

49. Authenticator Sync architecture
WIN #2: SYNC SCHEDULING
AccountManager
UI
SyncManager ContentResolver
SyncAdapter ContentProvider

50. Sync ON ANDROID
OVERVIEW ARCHITECTURE
CONTENT PROVIDER PITFALLS & PROTIPS

51. IDs in ContentProvider URIs
content://com.futuresimple.krakdroid.Provider/datasets/1

52. IDs in ContentProvider URIs
content://com.futuresimple.krakdroid.Provider/datasets/1
Plan A: Use local IDs! (BaseColumns._ID)

53. IDs in ContentProvider URIs
content://com.futuresimple.krakdroid.Provider/datasets/1
Plan A: Use local IDs! (BaseColumns._ID)
ISSUE: still need server-side IDs for relations

54. IDs in ContentProvider URIs
content://com.futuresimple.krakdroid.Provider/datasets/1
Plan A: Use local IDs! (BaseColumns._ID)
ISSUE: still need server-side IDs for relations
ISSUE: conversions between server and local IDs

55. IDs in ContentProvider URIs
content://com.futuresimple.krakdroid.Provider/datasets/15002900
Plan B: OK, use server-side IDs!

56. IDs in ContentProvider URIs
content://com.futuresimple.krakdroid.Provider/datasets/15002900
Plan B: OK, use server-side IDs!
ISSUE: what about offline mode?

57. IDs in ContentProvider URIs
content://com.futuresimple.krakdroid.Provider/datasets/-42
content://com.futuresimple.krakdroid.Provider/datasets/15002900
Plan C: OK, let’s mix things up!

58. IDs in ContentProvider URIs
content://com.futuresimple.krakdroid.Provider/datasets/-42
content://com.futuresimple.krakdroid.Provider/datasets/15002900
Plan C: OK, let’s mix things up!
ISSUE: very tricky implementation

59. IDs in ContentProvider URIs
content://com.futuresimple.krakdroid.Provider/datasets/GUID
Plan D: GUID

60. IDs in ContentProvider URIs
content://com.futuresimple.krakdroid.Provider/datasets/GUID
Plan D: GUID
ISSUE: needs support on the backend

61. ContentResolver requestSync() vs. notifyChange()
requestSync(account, authority, extras)
notifyChange(uri, observer, syncToNetwork)

62. ContentResolver requestSync() vs. notifyChange()
requestSync(account, authority, extras)
notifyChange(uri, observer, syncToNetwork)

63. Deleting an account
From your app
From system settings
From 3rd party app

64. Deleting an account
From your app
“Where should I
From system settings perform user
data cleanup?”
From 3rd party app

65. Deleting an account
@Override getAccountRemovalAllowed()

66. Deleting an account
@Override getAccountRemovalAllowed()
CONS: depends on current Settings implementation.
PROS: exactly the thing you need.

67. Deleting an account
<receiver
android:name=".auth.AccountBroadcastReceiver"
android:enabled="true" >
<intent-filter>
<action android:name="android.accounts.LOGIN_ACCOUNTS_CHANGED" />
</intent-filter>
</receiver>

68. Deleting an account
<receiver
android:name=".auth.AccountBroadcastReceiver"
android:enabled="true" >
<intent-filter>
<action android:name="android.accounts.LOGIN_ACCOUNTS_CHANGED" />
</intent-filter>
</receiver>
CONS: only info about existing accounts.
PROS: peace of mind.

69. Sync lifecycle
Happy case:

70. Sync lifecycle
Happy case:
requestSync()

71. Sync lifecycle
Happy case:
onPerformSync()
requestSync()

72. Sync lifecycle
Happy case:
onPerformSync()
requestSync() onStatusChanged()

73. Sync lifecycle
Not-so-happy case:
onPerformSync()
requestSync() onStatusChanged()

74. Sync lifecycle
Not-so-happy case:
onPerformSync()
requestSync() onStatusChanged()

75. Sync lifecycle
Not-so-happy case:
onPerformSync()
requestSync() cancelSync()
+
onStatusChanged()

76. Futureproof your sync

77. Futureproof your sync
1. Be lenient on GET

78. Futureproof your sync
1. Be lenient on GET
2. Be strict on POST

79. Futureproof your sync
1. Be lenient on GET
2. Be strict on POST
3. Have resync in v1.0

80. ?

83. Thanks.