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
   

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2. 2 @tsmith
   

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3. 3 @tsmith
   

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4. Deeplinks
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5. URI
   uber:// rideRequest ?pickup[latitude]=37.7749&pickup[longitude]=-122.4194
   Scheme Authority query
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6. Android Manifest
   android:name=".RideRequestActivity">
   
   
   
   
   
   
   
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7. Universal links
   https:// m.uber.com/ul/rideRequest ?pickup[latitude]=23.3219383&pickup[longitude]=121.23123422
   Scheme Authority query
   7 @tsmith
   

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8. Universal (Deferred) deeplinks
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9. 9 @tsmith
   

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10. App linking
    android:name=".RideRequestActivity">
    
    
    
    
    
    
    
    10 @tsmith
    

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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
    

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12. 12 @tsmith
    

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13. Three Legged Auth
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14. Single Sign-On
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15. Single Sign-On
    • Using URIs
    • Using intents with custom actions
    • Using the Android Account Manager
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16. Single Sign-On (URIs)
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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
    

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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
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19. 19 @tsmith
    

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20. Integration Requirements
    • Get Note(s)
    • List Notes
    • Create/Update Notes
    • Delete Notes
    • Account Sync
    • Get Preferences
    20 @tsmith
    

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21. Android Components Needed
    1. Intents
    2. Content Provider
    3. Account Manager
    4. Sync Adapter
    5. Inter Process Communication
    6. Permissions
    21 @tsmith
    

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22. Intents
    • Simple message between two components
    • Bundle - key/value data
    • Limited payload size (1MB)
    • Inefficient for batch operations
    • Defined Action
    22 @tsmith
    

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23. Intents
    Standard Actions
    • ACTION_SEND
    • ACTION_SEND_MULTIPLE
    • ACTION_VIEW
    • ACTION_EDIT
    23 @tsmith
    

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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
    

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25. Editing Intent
    Receiver
    
    
    
    
    
    
    
    25 @tsmith
    

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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
    

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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
    

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28. Intents
    Edit Caveats
    • Use copy of file
    • Don’t rely on setResult()
    • Use a ContentObserver
    • Check for file modified
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29. Intents
    Custom Actions
    com.example.action.note.*
    list - view - new - create
    edit - update - delete
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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
    

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31. Content Provider
    A well defined database access layer
    • SQLite
    • Interact with large volumes of data
    • Authority
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32. Content Provider
    URI
    content:// com.example / users / 1
    Scheme Authority Data Id
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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
    

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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
    

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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
    

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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
    

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37. Account Manager
    • Accessible Account
    • Authentication Token
    • Consistency
    37 @tsmith
    

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38. Providing your own Accounts
    • AbstractAccountAuthenticator
    • AccountAuthenticatorActivity
    38 @tsmith
    

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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
    

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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
    

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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
    

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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
    

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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
    

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45. Sync Adapter
    • Sync App and Web Service
    • User visible syncing
    • Network/battery optimized
    • Provided to third party apps
    • Schedule and GCM
    45 @tsmith
    

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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 = getImagesFromServer(authToken);
    updateImagesOnDisk(provider, images);
    }
    }
    46 @tsmith
    

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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
    

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48. Sync Adapter
    res/xml/sync_adapter.xml
    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
    

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49. Sync Adapter
    AndroidManifest.xml
    android:name=".syncadapter.ImagesSyncService"
    android:exported="true">
    
    
    
    android:name="android.content.SyncAdapter"
    android:resource="@xml/sync_adapter" />
    
    49 @tsmith
    

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50. Sync Adapter
    Sync Every Hour
    int interval = 3600;
    ContentResolver.addPeriodicSync(account,
    AppContract.AUTHORITY,
    new Bundle(),
    interval);
    50 @tsmith
    

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51. Sync Adapter
    Jitter
    int jitteredInterval = 3600 + new Random().nextInt(300);
    ContentResolver.addPeriodicSync(account,
    AppContract.AUTHORITY,
    new Bundle(),
    jitteredInterval);
    51 @tsmith
    

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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
    

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53. Binding Services
    Create AIDL
    interface RemoteMessageService {
    void passMessage(String "message");
    }
    53 @tsmith
    

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54. Binding Services
    Implement AIDL
    public class MessageBinder implements RemoteMessageService.Stub() {
    public void passMessage(String message) {
    Log.d(TAG, message);
    }
    }
    54 @tsmith
    

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55. Binding Services
    Expose Interface
    public class RemoteService extends Service {
    @Override
    public IBinder onBind(Intent intent) {
    return new MessageBinder;
    }
    }
    55 @tsmith
    

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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
    

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57. Permissions
    • Inform the User
    • Mitigate Exploits
    57 @tsmith
    

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58. Permissions
    Levels
    • Normal
    • Dangerous
    • Signature
    • SignatureOrSystem
    58 @tsmith
    

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59. Permissions
    Custom
    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
    

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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
    

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61. Permissions
    Enforcing via XML
    android:permissionGroup="com.example.permission-group.MYAPP_DATA"
    android:protectionLevel="dangerous" />
    android:permissionGroup="com.example.permission-group.MYAPP_DATA"
    android:protectionLevel="dangerous" />
    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
    

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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
    

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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
    

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64. Thanks!
    Ty Smith
    @tsmith
    developers.uber.com
    64 @tsmith
    

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