Building Top-Notch Android SDKs Hugo Doménech @hudomju #droidconit @droidconit

relayr bring things to life

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Building Top-Notch Android SDKs Hugo Doménech @hudomju

Agenda 1. Why? 2. How? 3. What?

Agenda 1. Why? 2. How? 3. What?

• Ease to use of the platform • Oauth, Http client, parsing, ble services… • Separate concerns • Branding Reasons

• Feel better - Sharing is caring • Code better - Power of shame • Easier to sell - quality prove • Get features and bug fixes for free • Security • It’s free • But most important… Be transparent: open source it!

Be Famous!

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Agenda 1. Why? 2. How? 3. What?

Decide what you are providing Library Project jar (Java ARchive) Apk Lib aar (Android Archive Resource) Library project, oldest standard android library project, standard checkout source code, you can link your source to, you can make reviews and edit it, but it’s not easy upgradable, there is no versioning. So it’s not the most flexible. JARs: great if you want to create a java library but they don’t include views or anything coming from android so if you don’t need it, it’s fine but as soon as you try to use some android related functionality it won’t work. ApkLibs: community focused effort around delivering library projects over a maven repository. It’s basically a compressed version of an android library project where the android maven plugin includes the library project in the generated source code folder. But it’s not the recommended way and it doesn’t play well with some tools. aar: recommended way by google, integrates seemlessly into gradle, supported by maven, it supports views. It’s a zip that compiles code and resources.

Let’s build a SDK!

Create a SDK!

Managing Releases Use the library in a real project SDK as a git submodule Master Master Develop Develop Feature Branch Feature Branch

Agenda 1. Why? 2. How? 3. What?

• Available • Easy to use • Flexible • Testable • Performant • Reliable • Lightweight Great SDK Qualities

Available dependencies { compile ‘io.relayr:android-sdk:0.0.5’ } build.gradle *gradle-mvn-push.gradle by Chris Banes

relayr bring things to life apply plugin: 'maven' apply plugin: ‘signing’ afterEvaluate { project -> uploadArchives { repositories { mavenDeployer { beforeDeployment { MavenDeployment deployment -> signing.signPom(deployment) } pom.groupId = ‘io.relayr’ pom.artifactId = ‘android-sdk’ pom.version = android.defaultConfig.versionName repository(url: mUrl) { authentication(userName: mUser, password: mPassword) }

relayr bring things to life pom.project { name ‘Relayr Android SDK’ packaging ‘aar’ description ‘SDK for connecting to the Relayr Cloud’ url ‘https://github.com/relayr/android-sdk/' licenses { license { name 'The MIT License' url 'http://ithings4u.mit-license.org/' distribution ‘repo' } } developers { developer { id 'hugodomenechjuarez' name 'Hugo Doménech Juárez' }

relayr bring things to life signing { required { isReleaseBuild() && gradle.taskGraph.hasTask(‘uploadArchives’) } sign configurations.archives } task androidJavadocsJar(type: Jar, dependsOn: bundleJavadocRelease) { classifier = 'javadoc' from bundleJavadocRelease.destinationDir } task androidSourcesJar(type: Jar) { classifier = 'sources' from android.sourceSets.main.java.sourceFiles } artifacts { archives androidSourcesJar archives androidJavadocsJar }

• Java code -> init(appId, clientId, clientSecret) • Java asset -> .properties • Android Manifest -> meta-data Easy to use - Initialisation

• Intuitive • Consistent • Easy to use, hard to misuse Easy to use

• RelayrSdk sdk = new RelayrSdk(context); • sdk.logMessage(“Hola!”); • Any problems? Easy to use

• RelayrSdk.init(context); • RelayrSdk.logMessage(“Hola!”); • Any problems? Easy to use

Flexible new RelayrSdk.Builder(this) .inMockMode(true) .apiEndpoint(“api.relayr.io”) .withLogger(new DefaultLogger()) .build();

Flexible - minimize permisions

Flexible - minimize permisions public boolean canAccessBluetooth() { String permission = "android.permission.BLUETOOTH"; int result = mContext.checkCallingOrSelfPermission(permission); return result == PackageManager.PERMISSION_GRANTED; }

Flexible - minimize requisites public boolean isBleSupported() { String feature = PackageManager.FEATURE_BLUETOOTH_LE; return getPackageManager().hasSystemFeature(feature); }

Flexible - support different versions defaultConfig { applicationId 'io.relayr.wunderbar' minSdkVersion 15 targetSdkVersion 21 versionCode 22 versionName '1.0.36' } public boolean isSdk18() { return android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2; }

mApplication.registerActivityLifecycleCallbacks( new Application.ActivityLifecycleCallbacks() { @Override public void onActivityResumed(Activity activity) { // we know there’s a UI! } } ); Flexible - be context aware

• Mock mode (no network requests) • No static methods • Avoid final classes Testable

Performant interface UserApi { List getDevices(); } interface UserApi { void getDevices(Callback callback); } interface UserApi { Observable> getDevices(); }

Performant List devices = user.getDevices(); user.getDevices(new Callback() { public void onSuccess(List devices) { } public void onError(Error error) { } }); user.getDevices() .subscribe( (List devices) -> { } )

• With Code Performant - Don’t log in production RelayrSdk.Builder(this) .setDebuggable(false) .build(); debuggable=false • On the Manifest

• Don’t crash silently - inform the user when a problem occurs Reliable RelayrSdk.login(new LoginCallback() { public void onSuccess(User user) { // sign the user into the app } public void onError(Error error) { // show error message } });

• Poor network conditions • Reluctance to include large libraries Lightweight

Lightweight - don’t require libraries private boolean hasOkHttpOnClasspath() { try { Class.forName("com.squareup.okhttp.OkHttpClient"); return true; } catch (ClassNotFoundException e) { } return false; } dependencies { provided ‘com.squareup.okhttp:okhttp:2.0.0’ }

Lightweight - be modular dependencies { } compile ‘io.relayr:java-sdk:0.0.5’ compile ‘io.relayr:android-sdk:0.0.5’ compile ‘io.relayr:android-onboarding:0.0.7’ compile ‘io.relayr:master-module:1.2.0’ compile ‘io.relayr:android-commons:1.0.0’

Take away

Questions? Hugo Doménech @hudomju

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