At Off Grid Electric our mission is to power homes across rural Africa with affordable, solar energy. In order to do that we need to provide our employees with tools that work both on and offline. So how did we do it? In this talk, learn about the techniques we employed to provide a unique online-offline experience in our Android applications. We’ll discuss the overall architecture, third party libraries used, and some of the challenges that we faced. As more and more users come online in various parts of the world it makes sense for companies to begin exploring how they can modify their applications to be more network-friendly. This talk will get you headed in the right direction!

1. NO INTERNET?
NO PROBLEM!

2. OFF GRID ELECTRIC
From: https://medium.com/@Offgrid

3. OFF GRID ELECTRIC

4. AGENDA
ARCHITECTURE
LIBRARIES
CHALLENGES

5. CHALLENGES

8. 3G COVERAGE IN ARUSHA, TZ

9. 4G LTE COVERAGE IN WASHINGTON, DC

10. DON’T ASSUME
BE RESILIENT

11. ARCHITECTURE

12. BE USEFUL
Our App ‣Store data locally
‣Separate UI and network
‣Queue requests

13. MVP(Model View Presenter)

14. EVENT BUS/RXJAVA
DATABASE
REPOSITORY
REPOSITORY
ACTIVITY
FRAGMENT
JOBS
PRESENTER
PRESENTER
SERVICE

15. DOWNLOAD ALL
THE THINGS

16. DISPLAY A VIEW
Is pre-populated
data needed?

17. EVENT BUS/RXJAVA
FRAGMENT PRESENTER SERVICE REPOSITORY DATABASE

18. TAKE AN ACTION
Is the Network
Available?

19. EVENT BUS/RXJAVA
FRAGMENT PRESENTER SERVICE REPOSITORY DATABASE
JOB

20. APP SERVER

21. CONFLICT RESOLUTION

22. REQUEST TIMESTAMPS

23. STATUS FIELDS
ACTION STATE

24. BUNDLING REQUESTS
/users/commissions
/users/info
/users/roles

25. BUNDLING REQUESTS
/users/commissions
/users/info
/users/roles
/users/me

26. EVENT BUS/RXJAVA
DATABASE
REPOSITORY
REPOSITORY
ACTIVITY
FRAGMENT
JOBS
PRESENTER
PRESENTER
SERVICE

27. LIBRARIES

28. WHAT WE USE
‣Realm
‣EventBus
‣Android Job

29. STORE DATA LOCALLY

31. REALM - MODEL CLASS
@RealmClass
public class Place implements RealmModel {
}

32. REALM - MODEL CLASS
@RealmClass
public class Place implements RealmModel {
@PrimaryKey
private String localId;
@Index
private Long remoteId;
private Gps location;
…
}

33. REALM - MODEL CLASS
localId remoteId location
19444498-2a40… 1458260
65031f36-bde9…
e85c9757-f546…

34. REALM - ADDING A RECORD
public class PlaceRepository implements Repository<Place> {
@Override
public void add (final Place item) {
}
…

35. REALM - ADDING A RECORD
public class PlaceRepository implements Repository<Place> {
@Override
public void add (final Place item) {
Realm realm = Realm.getDefaultInstance();
realm.executeTransaction((realm) -> {
realm.insertOrUpdate(item);
});
realm.close();
}
…

36. REALM - QUERY RESULT
@Override
public Place toResult (Realm realm) {
return realm.where(Place.class)
}

37. REALM - QUERY RESULT
@Override
public Place toResult (Realm realm) {
return realm.where(Place.class)
.equalTo(PLACE_ID, placeId)
.findFirst();
}

38. REALM - QUERY RESULT
@Override
public Place toResult (Realm realm) {
return realm.where(Place.class)
.equalTo(PLACE_ID, placeId)
.findFirst();
}

40. SEPARATE UI AND
NETWORK

41. EVENTBUS
From: http://greenrobot.org/eventbus

42. EVENTBUS - SETUP
@Provides
@Singleton
public Bus provideBus () {
return new Bus(EventBus.builder()
.logNoSubscriberMessages(BuildConfig.DEBUG)
.throwSubscriberException(false)
.build());
}

43. EVENTBUS - REGISTER
public class LeadsMapPresenter {
private final Bus bus;
private LeadsMapView leadsMapView;
@Inject
LeadsMapPresenter (Bus bus) {
this.bus = bus;
}
…

44. EVENTBUS - REGISTER
public class LeadsMapPresenter {
public void attachView (LeadsMapView view) {
this.leadsMapView = view;
bus.register(this);
}

45. EVENTBUS - REGISTER
public class LeadsMapPresenter {
public void attachView (LeadsMapView view) {
…
}
public void detachView () {
this.leadsMapView = null;
bus.unregister(this);
}

46. EVENT BUS/RXJAVA
FRAGMENT PRESENTER SERVICE REPOSITORY DATABASE
JOB

47. EVENTBUS - POST EVENT
api.submitPlace(place).enqueue(new Callback<Place>() {
…
JOB

48. EVENTBUS - POST EVENT
api.submitPlace(place).enqueue(new Callback<Place>() {
public void onResponse (…, Response<Place> response) {
if (response.isSuccessful()) {
}
…
JOB

49. EVENTBUS - POST EVENT
api.submitPlace(place).enqueue(new Callback<Place>() {
public void onResponse (…, Response<Place> response) {
if (response.isSuccessful()) {
Place updatedPlace = response.body();
bus.post(new PlaceSubmissionSuccessEvent(updatedPlace));
}
…
JOB

50. EVENTBUS - RETRIEVE EVENT
public class LeadsMapPresenter {
@Subscribe
public void handle (PlaceSubmissionSuccessEvent event) {
leadsMapView.displaySuccessMessage();
}
…
PRESENTER

51. EVENTBUS - SEND STATUS BAR NOTIFICATION
SERVICE

52. EVENTBUS - SEND STATUS BAR NOTIFICATION
SERVICE
@Subscribe(priority = 1)
open fun onEvent(event: PaymentSuccessEvent) {
}

53. EVENTBUS - SEND STATUS BAR NOTIFICATION
SERVICE
@Subscribe(priority = 1)
open fun onEvent(event: PaymentSuccessEvent) {
val notif = getString(R.string.payment_submitted_message)
createNotification(notif, 1)
}

55. QUEUE REQUESTS

58. ANDROID JOB

59. ANDROID JOB
‣Alarm Manager
‣Job Scheduler
‣GCM Network Manager

60. ANDROID JOB - COMPARISON
Library Min API Google Play?
JobScheduler 21 No
Firebase Job
Dispatcher
9 Yes
Android Job 14 No

61. ANDROID JOB
JOB MANAGER
JOB CREATOR

62. ANDROID JOB
JOB MANAGER
PROVIDER
JOB
JOB CREATOR
PROVIDER
JOB
PROVIDER
JOB

63. ANDROID JOB
JOB MANAGER
PROVIDER
JOB
JOB CREATOR
PROVIDER
JOB
PROVIDER
JOB
JOB REQUEST

64. ANDROID JOB
JOB MANAGER
PROVIDER
JOB
JOB CREATOR
PROVIDER
JOB
PROVIDER
JOB
JOB REQUEST
JOB

65. ANDROID JOB - CREATOR
public class ConfettiJobCreator implements JobCreator {
Map<String, Provider<Job>> jobs;
public Job create (String tag) {
}
}

66. ANDROID JOB - CREATOR
public Job create (String tag) {
Provider<Job> jobProvider = jobs.get(tag);
return jobProvider.get();
}

67. ANDROID JOB
JOB MANAGER
PROVIDER
JOB
JOB CREATOR
JOB REQUEST
JOB

68. ANDROID JOB - JOB EXECUTION
protected Result onRunJob (final Params params) {
}
JOB

69. ANDROID JOB - JOB EXECUTION
protected Result onRunJob (final Params params) {
PersistableBundleCompat extras = params.getExtras();
String placeId = extras.getString(PARAM_PLACE_ID);
}
JOB

70. ANDROID JOB - JOB EXECUTION
protected Result onRunJob (final Params params) {
PersistableBundleCompat extras = params.getExtras();
String placeId = extras.getString(PARAM_PLACE_ID);
return submitRequest(placeId) ? SUCCESS: FAILURE;
}
JOB

71. ANDROID JOB
JOB MANAGER
PROVIDER
JOB
JOB CREATOR
JOB REQUEST
JOB

72. ANDROID JOB - SCHEDULING
public static JobRequest get (String placeId) {
PersistableBundleCompat extras = …;
extras.putString(PARAM_PLACE_ID, placeId);
}

73. ANDROID JOB - SCHEDULING
public static JobRequest get (String placeId) {
PersistableBundleCompat extras = …;
extras.putString(PARAM_PLACE_ID, placeId);
return new JobRequest.Builder(SendPlaceRequestJob.JOB_TAG)
}

74. ANDROID JOB - SCHEDULING
public static JobRequest get (String placeId) {
PersistableBundleCompat extras = …;
extras.putString(PARAM_PLACE_ID, placeId);
return new JobRequest.Builder(SendPlaceRequestJob.JOB_TAG)
.setExecutionWindow(10_000L, 20_000L)
.setRequiredNetworkType(NetworkType.CONNECTED)
}

75. ANDROID JOB - SCHEDULING
public static JobRequest get (String placeId) {
PersistableBundleCompat extras = …;
extras.putString(PARAM_PLACE_ID, placeId);
return new JobRequest.Builder(SendPlaceRequestJob.JOB_TAG)
.setExecutionWindow(10_000L, 20_000L)
.setRequiredNetworkType(NetworkType.CONNECTED)
.setExtras(extras)
}

76. ANDROID JOB - SCHEDULING
public static JobRequest get (String placeId) {
PersistableBundleCompat extras = …;
extras.putString(PARAM_PLACE_ID, placeId);
return new JobRequest.Builder(SendPlaceRequestJob.JOB_TAG)
.setExecutionWindow(10_000L, 20_000L)
.setRequiredNetworkType(NetworkType.CONNECTED)
.setExtras(extras)
.setRequirementsEnforced(true)
.build();
}

77. if has network connection
attempt to submit request

78. if has network connection
attempt to submit request
else
queue request

79. ANDROID JOB - SCHEDULING
jobManager.schedule( );

80. ANDROID JOB - SCHEDULING
jobManager.schedule(SendPlaceRequestJob.buildJobRequest(id));
JOB REQUEST
JOB QUEUE

81. WHAT WE USE
‣Realm
‣EventBus
‣Android Job

82. WHAT’S NEXT?
‣SMS Fallback
‣Async Code Paths
‣Push Notifications

83. THANKS
@brwngrldev
adavis.info
---
@moyheen
medium.com/@moyinoluwa