Droidcon ES 16': How to fail going offline

Architecture proposal to work offline using mainly android components and a single dataflow

Transcript

1. HOW TO FAIL GOING OFFLINE @droidpl javier.pedro@mobgen.com javierdepedrolopez@gmail.com
2. Javier de Pedro López Strengths Experience Senior Android Developer 3 Years professionally 2 Different companies Free time architecture Design Patterns Gradle Code quality @droidpl javier.pedro@mobgen.com javierdepedrolopez@gmail.com
3. This talk Try & try & fail Architecture proposal Use case Show me the code
4. TRY & TRY & FAIL Section 1
5. Try & try & fail Pojos Services Sync Adapters Why I did investigate? • I work on an SDK similar to firebase • Should work offline • Should have a simple API • Should be reliable and user friendly Why This matters?
6. Try & try & fail Why This matters? Pojos Services Sync Adapters Why I did investigate? • Offline improves user experience • No loading times (most of the cases) • App always accesible • Just like magic
 • Makes your app less error prone
 • Forces the developer to think more mobile
 • Say no to: “you always have a good internet connection”
7. Try & try & fail Why This matters? Pojos Services Sync Adapters Why I did investigate? Views/MVP/ Interactors Using POJOS Database Callback Network Callback Pojo Callback
8. Try & try & fail Why This matters? Pojos Services Sync Adapters Why I did investigate? Using POJOS • Action cancellation • Lifecycle management • Single responsibility principle broken • Messy thread management • Hard to read code
 • Fast to implement
9. Try & try & fail Why This matters? Pojos Services Sync Adapters Why I did investigate? Views/MVP/ Interactors Using Services Service ResultReceiver/Binder Threading Database Sync Network Sync Pojo Callback
10. Try & try & fail Why This matters? Pojos Services Sync Adapters Why I did investigate? Problems using Services • Action cancellation is still a pain • Easy to leak memory
 • Easy to split in many services • Export to other apps • Easier to handle threading • Possibility to have many processes • Simplified callback system
11. Try & try & fail Why This matters? Pojos Services Sync Adapters Why I did investigate? Views/ MVP/ Interactors Using Sync Adapters Network Sync Sync adapter Sync trigger Database (content provider) Sync Content observer
12. Try & try & fail Why This matters? Pojos Services Sync Adapters Why I did investigate? Problems using Services • Hard disconnection errors • Sync adapter documentation • Sync adapter configuration (many files) • Too linked to accounts
 • Uses system tools • Content change notifications • All the benefits from services
13. ARCHITECTURE PROPOSAL Section 2
14. ARCHITECTURE PROPOSAL ACT LOCALLY SYNC GLOBALLY
15. Loaders Architecture proposal Job schedulers All together Read Write Loaders Repositories Views/ MVP/ Interactors Loader inits provides data gets notified android lifecycle asks for data Data source
16. Loader states Architecture proposal Job schedulers All together Read Write Loaders Repositories Started Stopped Reset Can load Can observe Can deliver Can load Can observe Can deliver Can load Can observe Can deliver Stop/Reset Start/Reset Start
17. Job schedulers Architecture proposal Job schedulers Loaders All together Read Write Repositories Pojo notifies notifies System Scheduler schedule job Preconditions check Sync Service trigger met Sync task run task
18. Repositories Architecture proposal Job schedulers Loaders All together Read Write Repositories Data Repository notifies Database Repository Read Write Other sources Network repository Read Write
19. Architecture proposal Job schedulers Loaders Overall diagram All together Read Write Repositories Data Repository Notifies Asks for data Loader Inits Provides data System Scheduler Schedule sync Sync Service Sync task Conditions met Run task Changes data Read Write Read Write Views/ MVP/ Interactors Start App SDK write
20. Architecture proposal Job schedulers Loaders All together Read Write Repositories SDK Loader Loader Loader Overall diagram App Layer Android SDK Entry Entry Entry Entry
21. Architecture proposal Job schedulers Loaders Read diagram All together Read Write Repositories
22. Architecture proposal Job schedulers Loaders Write diagram All together Read Write Repositories online
23. USE CASE Section 3
24. Use case Online sample Models offline Sample Articles and comments
25. Use case Online sample Models offline Sample
26. Use case Online sample Models offline Sample
27. SHOW ME THE CODE Section 4
28. Classes PostActivity PostLoader PostRepository PostDAO CommentDAO PostService SyncService SynchronizeTask write
29. Post Activity: init private PostRepository mRepository; private Executor mExecutor; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); mRepository = DemosApplication.instance() .demoSdk() .postRepository(); mExecutor = Executors.newSingleThreadExecutor(); startLoading(); PostLoader.init(getSupportLoaderManager(), this); } Views
30. Post Activity: load data @Override public Loader<List<Post>> onCreateLoader(int id, Bundle args) { return new PostLoader(this, DemosApplication.instance().demoSdk()); } @Override public void onLoadFinished(Loader<List<Post>> loader, List<Post> data) { stopLoading(); setAdapter(data); } @Override public void onLoaderReset(@NonNull Loader<List<Post>> loader) { //Do nothing } Views
31. Post Activity: Refresh @Override public void onRefresh() { startLoading(); PostLoader.getLoader(getSupportLoaderManager()).forceLoad(); } Views
32. Post Activity: Create post @Override public void onPostCreated(@NonNull final Post post) { startLoading(); mExecutor.execute(() -> { try { mRepository.localCreate(post); } catch (RepositoryException e) { showError(); } }); } Views
33. Post Activity: Delete post @Override public void onDeleted(@NonNull final Post post) { startLoading(); mExecutor.execute(() -> { try { mRepository.localDelete(post); } catch (RepositoryException e) { showError(); } }); } Views
34. post loader @Override public List<Post> loadInBackground() { setData(mDemoSdk.postRepository().posts()); return getData(); } @Override public void registerListener() { if (mObserver == null) { mObserver = SyncService.listenForUpdates(this); } } @Override public void unregisterListener() { if (mObserver != null) { SyncService.removeUpdateListener(this, mObserver); } } loader
35. Post repository: all posts @WorkerThread public List<Post> posts() { Response<List<Post>> postsResponse = mPostService.posts().execute(); if (postsResponse.isSuccessful()) { List<Post> posts = postsResponse.body(); mPostDao.deleteAll(); mPostDao.save(posts); } return mPostDao.posts(); } datasource
36. Post repository: Save @WorkerThread public void localCreate(@NonNull Post post) { mPostDao.save(post); SyncService.triggerSync(mContext); } @WorkerThread public void remoteCreate(@NonNull Post post) { Response<Post> postResponse = mPostService.create(Post.builder(post) .internalId(null) .needsSync(false) .build()).execute(); if (postResponse.isSuccessful()) { mPostDao.save(Post.builder(postResponse.body()) .internalId(post.internalId()) .build()); } } datasource
37. Post repository: DELETE @WorkerThread public void localDelete(@NonNull Post post) { long now = new Date().getTime(); if (post.isNew() && post.isStoredLocally()) { mPostDao.delete(post.internalId()); SyncService.notifyChange(mContext); } else { mPostDao.save(Post.builder(post) .deletedAt(now) .updatedAt(now) .needsSync(true).build()); SyncService.triggerSync(mContext); } } @WorkerThread public void remoteDelete(@NonNull Post post) { if (mPostService.deletePost(post.id()).execute().isSuccessful() && post.isStoredLocally()) { for (Comment comment : mCommentDao.comments(post.internalId())) { remoteDelete(comment); } mPostDao.delete(post.internalId()); } } datasource
38. Sync service: trigger public static void triggerSync(@NonNull Context context) { SyncService.notifyChange(context); ComponentName component = new ComponentName(context, SyncService.class); JobInfo info = new JobInfo.Builder(SYNC_SERVICE_ID, component) .setRequiredNetworkType(JobInfo.NETWORK_TYPE_ANY) .build(); getScheduler(context).schedule(info); } sync
39. Sync service: Listen for updates public static BroadcastReceiver listenForUpdates(@NonNull Loader loader) { IntentFilter filter = new IntentFilter(CHANGE_SYNC_INTENT_ACTION); SyncServiceReceiver receiver = new SyncServiceReceiver(loader); LocalBroadcastManager.getInstance(loader.getContext()) .registerReceiver(receiver, filter); return receiver; } public static void removeUpdateListener(@NonNull Loader loader, @NonNull BroadcastReceiver observer) { LocalBroadcastManager.getInstance(loader.getContext()) .unregisterReceiver(observer); } public static void notifyChange(@NonNull Context context) { LocalBroadcastManager.getInstance(context).sendBroadcast(getCompletionIntent()); } sync
40. Sync service: Do the JOB @Override public boolean onStartJob(JobParameters params) { DemoSdk sdk = DemoSdk.Factory.instance(); boolean willExecute = true; if (sdk != null) { mRunningSyncTask = new SynchronizeTask(sdk, this); mRunningSyncTask.execute(params); } else { willExecute = false; } return willExecute; } sync @Override public boolean onStopJob(JobParameters params) { boolean reschedule = false; if (mRunningSyncTask != null) { mRunningSyncTask.cancel(true); reschedule = true; } return reschedule; }
41. Sync task: Sync @Override protected JobParameters doInBackground(JobParameters... params) { syncPosts(); syncComments(); return params[0]; } sync private void syncPosts() { List<Post> posts = mSdk.postRepository().localPendingPosts(); for (Post post : posts) { if (post.isNew()) { mSdk.postRepository().remoteCreate(post); } else if (post.isDeleted()) { mSdk.postRepository().remoteDelete(post); } } }
42. Sync task: NOTIFY @Override protected void onPostExecute(JobParameters jobParameters) { super.onPostExecute(jobParameters); SyncService.notifyChange(mSyncService); mSyncService.jobFinished(jobParameters, mNeedsResync); } sync
43. And there you go! your app works offline
44. SOURCE Code available https://github.com/droidpl/offline-architecture @droidpl
45. Conclusions Offline matters because UX matters It is part of the architecture Not so much effort with the right choice Unique dataflow Don’t reinvent the wheel - Android has it -
46. …………………… We are hiring! Ask
47. …………………… Q&A
48. …………………… Thank you!