Deep Android Integrations

Designing an elegant interface for developers to communicate with your Android app is crucial for building a mobile platform. Ty has been building mobile-focused developer platforms at Evernote, Twitter, and now Uber. In this talk, he'll walk you through many of the best practices that he has accumulated and you’ll find out how to allow third party developers to seamlessly interact with your users’ local data to shortcut more expensive server operations.

Topics will include building single sign-on, surfacing your local databases, constructing well-defined Intent interfaces, using deep links, and binding services for programmatic communication. Ty will walk you through how to create a well-defined interface in your app – if that’s something you want to know, don’t miss it!

Transcript

1. Deep Android Integrations Ty Smith Mobile Tech Lead at Uber 1 @tsmith
2. 2 @tsmith
3. 3 @tsmith
4. Deeplinks 4 @tsmith
5. URI uber:// rideRequest ?pickup[latitude]=37.7749&pickup[longitude]=-122.4194 Scheme Authority query 5 @tsmith
6. Android Manifest <activity android:name=".RideRequestActivity"> <intent-filter> <action android:name="android.intent.action.VIEW"/> <category android:name="android.intent.category.DEFAULT"/> <category android:name="android.intent.category.BROWSABLE"/> <data android:scheme="uber" android:authority="rideRequest"/> </intent-filter> </activity> 6 @tsmith
7. Universal links https:// m.uber.com/ul/rideRequest ?pickup[latitude]=23.3219383&pickup[longitude]=121.23123422 Scheme Authority query 7 @tsmith
8. Universal (Deferred) deeplinks 8 @tsmith
9. 9 @tsmith
10. App linking <activity android:name=".RideRequestActivity"> <intent-filter android:autoVerify="true"> <action android:name="android.intent.action.VIEW"/> <category android:name="android.intent.category.DEFAULT"/> <category android:name="android.intent.category.BROWSABLE"/> <data android:scheme="uber" android:authority="rideRequest"/> </intent-filter> </activity> 10 @tsmith
11. App linking $ keytool -list -v -keystore my-release-key.keystore # https://domain[:optional_port]/.well-known/assetlinks.json [{ "relation": ["delegate_permission/common.handle_all_urls"], "target": { "namespace": "android_app", "package_name": "com.example", "sha256_cert_fingerprints": ["14:6D:E9:83:C5:73:06:50:D8:EE:B9:95:2F:34:FC:64:16:A0:83:42:E6:1D:BE:A8:8A:04:96:B2:3F:CF:44:E5"] } }] 11 @tsmith
12. 12 @tsmith
13. Three Legged Auth 13 @tsmith
14. Single Sign-On 14 @tsmith
15. Single Sign-On • Using URIs • Using intents with custom actions • Using the Android Account Manager 15 @tsmith
16. Single Sign-On (URIs) 16 @tsmith
17. Single Sign-On Security Intent intent = new Intent(Intent.ACTION_VIEW); final Uri deepLinkUri = createSsoUri(); intent.setData(deepLinkUri); intent.setPackage("com.ubercab"); activity.startActivityForResult(intent, requestCode); 17 @tsmith
18. Single Sign-On Security PackageInfo packageInfo = packageManager.getPackageInfo( packageName, PackageManager.GET_SIGNATURES); for (Signature signature : packageInfo.signatures) { String hashedSignature = Utility.sha1hash(signature.toByteArray()); if (!validAppSignatureHashes.contains(hashedSignature)) { //Invalid Signature } } //Valid signature 18 @tsmith
19. 19 @tsmith
20. Integration Requirements • Get Note(s) • List Notes • Create/Update Notes • Delete Notes • Account Sync • Get Preferences 20 @tsmith
21. Android Components Needed 1. Intents 2. Content Provider 3. Account Manager 4. Sync Adapter 5. Inter Process Communication 6. Permissions 21 @tsmith
22. Intents • Simple message between two components • Bundle - key/value data • Limited payload size (1MB) • Inefficient for batch operations • Defined Action 22 @tsmith
23. Intents Standard Actions • ACTION_SEND • ACTION_SEND_MULTIPLE • ACTION_VIEW • ACTION_EDIT 23 @tsmith
24. Editing Intent Sender public void editImage(String mimeType, Uri imageUri) { Intent intent = new Intent(Intent.ACTION_EDIT); intent.setType(mimeType); intent.setData(imageUri); startActivityForResult(intent, RESULT_CODE); } 24 @tsmith
25. Editing Intent Receiver <activity android:name=".ui.IntentActivity" > <intent-filter> <action android:name="android.intent.action.ACTION_EDIT" /> <category android:name="android.intent.category.DEFAULT" /> <data android:mimeType="image/*" /> </intent-filter> </activity> 25 @tsmith
26. Editing Intent Receiver @Override protected void onNewIntent(Intent intent) { switch(intent.getAction()) { case Intent.ACTION_EDIT: if (intent.getType().startsWith("image/")) { editImage(intent.getData()); setResult(RESULT_OK, intent); finish(); } } } 26 @tsmith
27. Editing Intent Sender @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode = RESULT_CODE && RESULT_OK == resultCode) { Uri imageUri = data.getData(); //Update UI with new image } } 27 @tsmith
28. Intents Edit Caveats • Use copy of file • Don’t rely on setResult() • Use a ContentObserver • Check for file modified 28 @tsmith
29. Intents Custom Actions com.example.action.note.* list - view - new - create edit - update - delete 29 @tsmith
30. Intents Custom Actions public void newNoteWithContent(Uri image) { Intent intent = new Intent(); intent.setAction(NEW_NOTE); intent.putExtra(Intent.EXTRA_TITLE, "LET ME EXPLAIN YOU INTENTS"); intent.putExtra(Intent.EXTRA_TEXT, "¯\_(ϑ)_/¯"); intent.setData(image); startActivityForResult(intent); } 30 @tsmith
31. Content Provider A well defined database access layer • SQLite • Interact with large volumes of data • Authority 31 @tsmith
32. Content Provider URI content:// com.example / users / 1 Scheme Authority Data Id 32 @tsmith
33. Content Provider Query public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) { SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder(); switch (URIMatcher.match(uri)) { USERS_LIST: queryBuilder.setTables(MyDBHandler.TABLE_USERS); } Cursor cursor = queryBuilder.query(myDB.getReadableDatabase(), projection, selection, selectionArgs, null, null, sortOrder); cursor.setNotificationUri(getContext().getContentResolver(), uri); return cursor; } 33 @tsmith
34. Content Resolver Query Uri uri = Uri.parse("content://com.example/users"); String[] projection = new String[]{"username", “email”}; String selection = “name LIKE ?”; String[] args = new String[]{"Ty"}; String sort = “email ASC”; getContentResolver().query(uri, projection, selection, args, sort); 34 @tsmith
35. Content Provider Serving Files @Override public ParcelFileDescriptor openFile(Uri uri, String mode) throws FileNotFoundException { File path = new File(getContext().getCacheDir(), uri.getEncodedPath()); int imode = 0; if (mode.contains("w")) { imode |= ParcelFileDescriptor.MODE_WRITE_ONLY; if (!path.exists()) { try { path.createNewFile(); //TODO: Handle IOException } } if (mode.contains("r")) imode |= ParcelFileDescriptor.MODE_READ_ONLY; if (mode.contains("+")) imode |= ParcelFileDescriptor.MODE_APPEND; return ParcelFileDescriptor.open(path, imode); } 35 @tsmith
36. Content Resolver Getting Files ContentResolver resolver = getContentResolver(); URI imageUri = Uri.parse("content://com.example/images/1"); String mode = "rw+" ParcelFileDescriptor pfd = resolver.openFileDescriptor(imageUri, mode); FileDescriptor fileDescriptor = pfd.getFileDescriptor(); InputStream fileStream = new FileInputStream(fileDescriptor); //Magic here! 36 @tsmith
37. Account Manager • Accessible Account • Authentication Token • Consistency 37 @tsmith
38. Providing your own Accounts • AbstractAccountAuthenticator • AccountAuthenticatorActivity 38 @tsmith
39. 39 @tsmith
40. AbstractAccountAuthenticator addAccount @Override public Bundle addAccount(AccountAuthenticatorResponse response, String accountType, String authTokenType, String[] requiredFeatures, Bundle options) throws NetworkErrorException { final Intent intent = new Intent(mContext, AuthenticatorActivity.class); intent.putExtra(AuthenticatorActivity.ARG_ACCOUNT_TYPE, accountType); intent.putExtra(AuthenticatorActivity.ARG_AUTH_TYPE, authTokenType); intent.putExtra(AuthenticatorActivity.ARG_IS_ADDING_NEW_ACCOUNT, true); intent.putExtra(AccountManager.KEY_ACCOUNT_AUTHENTICATOR_RESPONSE, response); final Bundle bundle = new Bundle(); bundle.putParcelable(AccountManager.KEY_INTENT, intent); return bundle; } 40 @tsmith
41. AbstractAccountAuthenticator getAuthToken @Override public Bundle getAuthToken(AccountAuthenticatorResponse response, Account account, String authTokenType, Bundle options) throws NetworkErrorException { final AccountManager am = AccountManager.get(mContext); String authToken = am.peekAuthToken(account, authTokenType); if (TextUtils.isEmpty(authToken)) { final String password = am.getPassword(account); if (password != null) { authToken = serverAuthenticate.userSignIn(account.name, password, authTokenType); } } ... 41 @tsmith
42. AbstractAccountAuthenticator getAuthToken ... if (!TextUtils.isEmpty(authToken)) { final Bundle result = new Bundle(); result.putString(AccountManager.KEY_ACCOUNT_NAME, account.name); result.putString(AccountManager.KEY_ACCOUNT_TYPE, account.type); result.putString(AccountManager.KEY_AUTHTOKEN, authToken); return result; } ... 42 @tsmith
43. AbstractAccountAuthenticator getAuthToken ... final Intent intent = new Intent(mContext, AuthenticatorActivity.class); intent.putExtra(AccountManager.KEY_ACCOUNT_AUTHENTICATOR_RESPONSE, response); intent.putExtra(AuthenticatorActivity.ARG_ACCOUNT_TYPE, account.type); intent.putExtra(AuthenticatorActivity.ARG_AUTH_TYPE, authTokenType); final Bundle bundle = new Bundle(); bundle.putParcelable(AccountManager.KEY_INTENT, intent); return bundle; } 43 @tsmith
44. AccountAuthenticatorActivity Success private void finishLogin(String accountName, String accountType, String password, String authToken, String authTokenType) { Account account = new Account(accountName, accountType); if (getIntent().getBooleanExtra(ARG_IS_ADDING_NEW_ACCOUNT, false)) { accountManager.addAccountExplicitly(account, password, null); } accountManager.setPassword(account, password); accountManager.setAuthToken(account, authTokenType, authToken); Intent intent = new Intent(); intent.putExtra(AccountManager.KEY_ACCOUNT_NAME, userName); intent.putExtra(AccountManager.KEY_ACCOUNT_TYPE, ACCOUNT_TYPE); intent.putExtra(AccountManager.KEY_AUTHTOKEN, authToken); setAccountAuthenticatorResult(intent.getExtras()); setResult(RESULT_OK, intent); finish(); } 44 @tsmith
45. Sync Adapter • Sync App and Web Service • User visible syncing • Network/battery optimized • Provided to third party apps • Schedule and GCM 45 @tsmith
46. Sync Adapter public class ImagesSyncAdapter extends AbstractThreadedSyncAdapter { private final AccountManager accountManager; public TvShowsSyncAdapter(Context context, boolean autoInitialize) { super(context, autoInitialize); accountManager = AccountManager.get(context); } @Override public void onPerformSync(Account account, Bundle extras, String authority, ContentProviderClient provider, SyncResult syncResult) { String authToken = accountManager.blockingGetAuthToken(account, AccountGeneral.AUTHTOKEN_TYPE_FULL_ACCESS, true); List<Images> images = getImagesFromServer(authToken); updateImagesOnDisk(provider, images); } } 46 @tsmith
47. Sync Adapter public class ImagesSyncService extends Service { private static final Object syncAdapterLock = new Object(); private static ImagesSyncAdapter syncAdapter = null; @Override public void onCreate() { synchronized (syncAdapterLock) { if (syncAdapter == null) syncAdapter = new ImagesSyncAdapter(getApplicationContext(), true); } } @Override public IBinder onBind(Intent intent) { return syncAdapter.getSyncAdapterBinder(); } } 47 @tsmith
48. Sync Adapter res/xml/sync_adapter.xml <sync-adapter xmlns:android="http://schemas.android.com/apk/res/android" android:contentAuthority="com.example.images.provider" android:accountType="com.example.sync_example" android:userVisible="true" android:allowParallelSyncs="false" android:isAlwaysSyncable="false" android:supportsUploading="true"/> 48 @tsmith
49. Sync Adapter AndroidManifest.xml <service android:name=".syncadapter.ImagesSyncService" android:exported="true"> <intent-filter> <action android:name="android.content.SyncAdapter" /> </intent-filter> <meta-data android:name="android.content.SyncAdapter" android:resource="@xml/sync_adapter" /> </service> 49 @tsmith
50. Sync Adapter Sync Every Hour int interval = 3600; ContentResolver.addPeriodicSync(account, AppContract.AUTHORITY, new Bundle(), interval); 50 @tsmith
51. Sync Adapter Jitter int jitteredInterval = 3600 + new Random().nextInt(300); ContentResolver.addPeriodicSync(account, AppContract.AUTHORITY, new Bundle(), jitteredInterval); 51 @tsmith
52. Binding Services for IPC • Android Interface Definition Language (AIDL) • Communicate between process or app • Directly call defined RPC methods • Requires consumer to contain interface 52 @tsmith
53. Binding Services Create AIDL interface RemoteMessageService { void passMessage(String "message"); } 53 @tsmith
54. Binding Services Implement AIDL public class MessageBinder implements RemoteMessageService.Stub() { public void passMessage(String message) { Log.d(TAG, message); } } 54 @tsmith
55. Binding Services Expose Interface public class RemoteService extends Service { @Override public IBinder onBind(Intent intent) { return new MessageBinder; } } 55 @tsmith
56. Binding Services Connecting private ServiceConnection connection = new ServiceConnection() { public void onServiceConnected(ComponentName className, IBinder service) { service = IRemoteService.Stub.asInterface(service); } public void onServiceDisconnected(ComponentName className) { service = null; } } public void onResume() { bindService(new Intent(this, RemoteMessageService.class), connection, Context.BIND_AUTO_CREATE); } public void onPause() { unbindService(connection); service = null; } 56 @tsmith
57. Permissions • Inform the User • Mitigate Exploits 57 @tsmith
58. Permissions Levels • Normal • Dangerous • Signature • SignatureOrSystem 58 @tsmith
59. Permissions Custom <permission android:name="com.example.perm.READ" android:label="@string/permission_label" android:description="@string/permission_description" android.protectionLevel="dangerous" android:permissionGroup="com.example.permission-group.MYAPP_DATA" /> • Can be used to restrict access to various services and components • Required to interact with app that declares it • Can be checked programatically or via Manifest. 59 @tsmith
60. Permissions Enforcing programatically int canProcess = getContext().checkCallingPermission("com.example.perm.READ"); if (canProcess != PERMISSION_GRANTED) { throw new SecurityException("Requires Custom Permission"); } • checkCallingOrSelfPermission() can leak permissions 60 @tsmith
61. Permissions Enforcing via XML <permission android:name="com.example.perm.READ" android:permissionGroup="com.example.permission-group.MYAPP_DATA" android:protectionLevel="dangerous" /> <permission android:name="myapp.permission.WRITE" android:permissionGroup="com.example.permission-group.MYAPP_DATA" android:protectionLevel="dangerous" /> <provider android:name=".data.DataProvider" android:exported="true" android:authorities="com.example.data.DataProvider" android:readPermission="com.example.perm.READ" android:writePermission="com.example.perm.WRITE" /> 61 @tsmith
62. Integration Requirements • Get Note(s) (Intent & Content Provider) • List Notes (Intent) • Create/Update Notes (Intent & Content Provider) • Delete Notes (Intent & Content Provider) • Account Sync (Account Manager & Sync Adapter) • Get Preferences (Content Provider and bound Services) 62 @tsmith
63. Debugging Tips • Debugging app integrations is hard • Logging is your friend • Test with mock integrations • Communicate your data contracts • Seek User Feedback • Analytics and Crash Reporting 63 @tsmith
64. Thanks! Ty Smith @tsmith developers.uber.com 64 @tsmith