Building Top-Notch Android SDKs Hugo Doménech @hudomju

relayr bring things to life

relayr bring things to life easy tools to connect things and apps

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relayr bring things to life By the way, one of you has a chance to win a WunderBar today!! dev.relayr.io/signup

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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?

• Developers are lazy - reuse code • Separate concerns (build independent blocs) • Write better software • Speed up compile time • Make other people happy… Reasons

• Feel better • Code better: Power of shame • Get features and bug fixes for free • Easier to sell - quality prove • Excitement from the community • Security • It’s free • But most important… Make it open source!

Be Famous!

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! How do we start? Before writing a single line of code, what do we need? (public)

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 { include ‘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 canVibrate() { String permission = "android.permission.VIBRATE"; 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 '1.0.22' } 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

• Don’t block the current thread! Performant RelayrSdk.sendMessage(“At droidcon Tunisia!”);

• 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 { } include ‘io.relayr:java-sdk:0.0.5’ include ‘io.relayr:android-sdk:0.0.5’ include ‘io.relayr:android-onboarding:0.0.7’ include ‘io.relayr:master-module:1.2.0’ include ‘io.relayr:android-commons:1.0.0’

Take away Everyone should be building their code thinking about libraries. There are always parts of your applications that could be separated into different projects, generalised and published for other people to benefit from. You will end up writing better code and being happier.

Questions? Hugo Doménech @hudomju

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