Droidcon ES '16 - How to fail going offline
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Architecture proposal to work offline using mainly android components and a single dataflow
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Droidcon ES '16 - How to fail going offline
- 3. Thistalk Try & try & fail Architecture proposal Use case Show me the code
- 5. Try&try&fail Pojos Services SyncAdapters WhyIdidinvestigate? • I work on an SDK similar to firebase • Should work offline • Should have a simple API • Should be reliable and user friendly WhyThismatters?
- 6. Try&try&fail WhyThismatters? Pojos Services SyncAdapters WhyIdidinvestigate? • 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”
- 8. Try&try&fail WhyThismatters? Pojos Services SyncAdapters WhyIdidinvestigate? Using POJOS • Action cancellation • Lifecycle management • Single responsibility principle broken • Messy thread management • Hard to read code • Fast to implement
- 10. Try&try&fail WhyThismatters? Pojos Services SyncAdapters WhyIdidinvestigate? 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
- 12. Try&try&fail WhyThismatters? Pojos Services SyncAdapters WhyIdidinvestigate? 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
- 15. LoadersArchitecture proposal Jobschedulers Alltogether Read Write Loaders Repositories Views/ MVP/ Interactors Loader inits provides data gets notified android lifecycle asks for data Data source
- 16. Loader statesArchitecture proposal Jobschedulers Alltogether 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
- 19. Architecture proposal Jobschedulers Loaders Overall diagram Alltogether Read Write Repositories Data Repository Notifies Asks for data Loader Inits Provides data System Scheduler Schedule sync Sync Service Sync task Conditions metRun task Changes data Read Write Read Write Views/ MVP/ Interactors Start App SDK write
- 22. Architecture proposal Jobschedulers Loaders Write diagram Alltogether Read Write Repositories online
- 29. PostActivity: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. PostActivity:loaddata @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. PostActivity:Refresh @Override public void onRefresh() { startLoading(); PostLoader.getLoader(getSupportLoaderManager()).forceLoad(); } Views
- 32. PostActivity:Createpost @Override public void onPostCreated(@NonNull final Post post) { startLoading(); mExecutor.execute(() -> { try { mRepository.localCreate(post); } catch (RepositoryException e) { showError(); } }); } Views
- 33. PostActivity:Deletepost @Override public void onDeleted(@NonNull final Post post) { startLoading(); mExecutor.execute(() -> { try { mRepository.localDelete(post); } catch (RepositoryException e) { showError(); } }); } Views
- 34. postloader @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. Postrepository:allposts @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. Postrepository: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. Postrepository: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. Syncservice: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. Syncservice:Listenforupdates 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. Syncservice:DotheJOB @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. Synctask: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. Synctask:NOTIFY @Override protected void onPostExecute(JobParameters jobParameters) { super.onPostExecute(jobParameters); SyncService.notifyChange(mSyncService); mSyncService.jobFinished(jobParameters, mNeedsResync); } sync
- 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 -
- 47. …………………… Q&A