Building First Class Android Sdks

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Building First Class Android SDK January 15, 2015 #AndroidDevSdks

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January 15, 2015 #AndroidDevSdks SDK PEPINO

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Israel Ferrer Camacho Senior Software Engineer @rallat

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Fabric Sample App Cannonball https://github.com/twitterdev

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What means to be a First Class SDK?

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Modular

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ABOMINATION

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Modularity Fabric.with(this, new Twitter()); Fabric.with(this, new TweetUi(), new TweetComposer());

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Fabric.aar Cache Settings Concurrency Events Network Persistence

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Fabric.aar Cache Settings Concurrency Events Network Persistence KitCore Kit Common Services

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Fabric.aar Cache Settings Concurrency Events Network Persistence KitCore Kit A Kit C Kit B Features Kit Common Services

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Fabric.aar Cache Settings Concurrency Events Network Persistence KitCore Kit A Kit C Kit B KitInterface Interface Features Kit Common Services

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Fabric.aar Cache Settings Concurrency Events Network Persistence TwitterCore.aar TweetUi.aar Digits.aar TweetComposer.aar Twitter.aar Interface Features Kit Common Services

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Extensible

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Fabric fabric = new Fabric.Builder(this) .kits(new Crashlytics()) .initializationCallback( new Callback() { void success(Fabric fabric) { } void failure(Exception exception) { } }) .build(); Callbacks

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Extensible Interfaces interface Logger { void d(String tag, String text, Throwable throwable); void v(String tag, String text, Throwable throwable); void i(String tag, String text, Throwable throwable); void w(String tag, String text, Throwable throwable); void e(String tag, String text, Throwable throwable); }

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Sane Defaults public class DefaultLogger { public DefaultLogger(int logLevel) { this.logLevel = logLevel; } void d(String tag, String text, Throwable throwable) { if (isLoggable(tag, Log.DEBUG)) Log.d(tag, text, throwable); } ... }

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Extensible Classes class MyApiClient extends TwitterApiClient { interface MyService { @GET(“/1.1/statuses/show.json”) Tweet getTweet(@Query(“id”) int id); } MyService getMyService() { return getService(MyService.class); } }

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Extensible View Styles <item name="tw__container_bg_color"> @color/tw__tweet_light_container_bg_color </item> <item name="tw__primary_text_color"> @color/tw__tweet_light_primary_text_color </item> <item name="tw__action_color"> @color/tw__tweet_action_color </item>

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Easy to Use Hard to Misuse

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>[]+{} Javascript example

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>[]+{} [Object object] Javascript example

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>[]+{} [Object object] >{}+[] Javascript example

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>[]+{} [Object object] >{}+[] 0 Javascript example

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WAT

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WAT

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Crashlytics.start(this, 5); Crashlytics.setListener(createCrashlyticsListener()); Crashlytics.setPinningInfo(createPinningInfoProvider()) Crashlytics.getInstance().setDebugMode(true); Initialization

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Crashlytics.setListener(createCrashlyticsListener()); Crashlytics.setPinningInfo(createPinningInfoProvider()); Crashlytics.getInstance().setDebugMode(true); Crashlytics.start(this, 5); Initialization

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Crashlytics.start(this, delay, listener, pinningInfo, debugMode); Initialization

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Crashlytics.start(this, 0, null, null, null, true); Initialization

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Crashlytics crashlytics = new Crashlytics.Builder() .delay(1) .listener(createCrashlyticsListener()) .pinningInfo(createPinningInfoProvider()) .build(); Fabric.with(this, crashlytics); Fluent Pattern

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Fabric.with(new Fabric.Builder(this) .kits(new Crashlytics()) .debuggable(true) .logger(new DefaultLogger(Log.VERBOSE)) .looper(getCustomLooper()) .executor(getCustomExecutorService()) .build()); Fluent Pattern

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Adapter Pattern public class TweetViewFetchAdapter extends TweetViewAdapter { … } public class TweetViewAdapter extends BaseAdapter { … }

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Styling <item name="android:textColorPrimary"> @android:color/black</item> <item name="android:textColorSecondary"> @android:color/darker_gray</item> <item name="android:windowBackground"> @android:color/white</item> <item name="android:textColorLink">#ff398622</item> <item name="android:colorAccent">#ff398622</item>

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Intuitive method naming Digits.authenticate(new AuthCallback() { @Override public void success(DigitsSession session, String phoneNumber) { } @Override public void failure(DigitsException error) { } }); adapter.setTweetIds(tweetIds, new LoadCallback<>() {…});

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Detecting Dependencies …

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public static Fabric with(Context context) { Context appContext = context.getApplicationContext(); ApplicationInfo ai = context.getPackageManager() .getApplicationInfo(ac.getPackageName(),  PackageManager.GET_META_DATA); String apiKey = ai.metaData.getString(API_KEY); return new Fabric(appContext, apiKey); } Detecting Dependencies

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public TwitterApiClient { final Session session; public TwitterApiClient(Session session) { this.session = session; } public TwitterApiClient() { this.session = Twitter.getSessionManager().getActiveSession(); } } Detecting Dependencies

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Minimizing Permissions

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Minimizing Permissions

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Minimizing Permissions crashlytics.setUserEmail(“[email protected]”);

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Permissions Detection protected boolean canCheckNetworkState(Context context) { String permission = Manifest.permission.ACCESS_NETWORK_STATE; int result = context.checkCallingOrSelfPermission(permission); return (result == PackageManager.PERMISSION_GRANTED); }

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Optional Features …

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Features Detection protected boolean hasCamera(Context context) { PackageManager pm = context.getPackageManager(); String camera = PackageManager.FEATURE_CAMERA; return pm.hasSystemFeature(camera); }

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Android Version Detection if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.FROYO) { return formatID(Build.HARDWARE);  } return null;

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Intent Detection try { startActivityForResult(new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH), 0); } catch (ActivityNotFoundException e){ }

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Intent Detection PackageManager pm = context.getApplicationContext().getPackageManager(); List activities = pm.queryIntentActivities( new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH),0); if (activities.size() > 0) { //an app exists that can recognize speech }

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Classpath Detection private boolean hasOkHttpOnClasspath() { try { Class.forName("com.squareup.okhttp.OkHttpClient"); return true; } catch (ClassNotFoundException e) { } return false; } provided 'com.squareup.okhttp:okhttp:2.0.0'

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Classpath Detection public class DefaultClient implements Client { private final Client client; public DefaultClient() { if (hasOkHttpOnClasspath()) { client = new OkClient(); } else { client = new UrlConnectionClient(); } } … }

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Catch unexpected exceptions try { //Do all the things! } catch (Exception e){ //Log something meaningful }

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Throw expected exceptions /** * Sets the {@link io.fabric.sdk.android.Logger} * @throws java.lang.IllegalArgumentException */ public Builder logger(Logger logger) { if (logger == null) { throw new IllegalArgumentException( "Logger must not be null."); } this.logger = logger; return this; }

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Gracefully Degrade if (TextUtils.isEmpty(apiKey) if (debuggable){ throw new IllegalArgumentException(“apiKey is null!"); } else { Logger.e(…); return null; } }

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Testable

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Make it Testable/Mockable Avoid static methods

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Make it Testable/Mockable Avoid static methods Avoid final classes and accessing fields directly

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Make it Testable/Mockable Avoid static methods Avoid final classes and accessing fields directly Utilize interfaces around entry points

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Make it Testable/Mockable Avoid static methods Avoid final classes and accessing fields directly Utilize interfaces around entry points Provide test package in separate artifact

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Hard to Test package com.example; public final class Tweeter { private Network network; public static Tweeter getInstance() {...} private Tweeter() { this.network = new Network(); } public List getTweets() { return network.getTweets(); } }

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Easy to Test package com.example; public final class Tweeter { private Network network; public static Tweeter getInstance() {...} private public Tweeter(Network network) { this.network = new Network() network; } public List getTweets() { return getNetwork().getTweets(); } … }

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Using in Tests package com.example.Tweeter; public class MyTest extends AndroidTestCase { Tweeter tweeter; @Override public void setup() { tweeter = mock(Tweeter.class); } ... }

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High-performance

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Size

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Size

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3rd Party Library Mindfulness

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3rd Party Library Mindfulness PROTOBUF KB

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3rd Party Library Mindfulness PROTOBUF KB OURS KB

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How big are Fabric AARs? Fabric: 190kb Crashlytics: 90kb Beta: 13kb Answers: 20kb Twitter API & SSO: 296kb Tweet UI: 120kb Tweet Composer: 5kb Digits: 236kb

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Reporting Binary Size task reportSdkFootprint << { def sdkProject = project(':clients:SdkProject') def nonSdkProject = project(':clients:NonSdkProject') def crashlyticsFootprint = getSizeDifference( new File("${sdkProject.buildDir}.../Sdk.apk"), new File("${nonSdkProject.buildDir}.../NonSdk.apk") ) println crashlyticsFootprint }

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Dalvik Method Count >./gradlew assemble … Unable to execute dex: method ID not in [0,   0xffff]: 65536 Conversion to Dalvik format failed: Unable to   execute dex: method ID not in [0, 0xffff]: 65536

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Dalvik Method Count > git clone [email protected]:mihaip/dex-method-counts.git > cd dex-method-counts > ant jar > ./dex-method-counts path/to/App.apk Read in 65490 method IDs. : 65490 : 3 accessibilityservice: 6 bluetooth: 2 content: 248 pm: 22 res: 45 com: 53881 example: 283 sdk: 283