Building an Android Instant app (Google I/O '17)

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Building an Android Instant app (Google I/O '17)

[MUSIC PLAYING] SHOBANA RAVI: Hi, good afternoon Welcome to our session on building an Android Instant App I’m Shobana, I’m the engineering lead for developer experience of Instant Apps I’ve been on the team since the very beginning So I’m very excited to be here today to bring all of you, our Instant Apps development experience So today, I’m going to talk to you about what Instant Apps are, give you a quick overview of the user experiences that they enable I’ll then talk about a few key principles to keep in mind as you build your Instant App I’ll walk you through the developer experience that we built that you can expect when you start And then finally, we’ll work through a specific example of building an Instant App from an existing app Sounds good? Let’s get started So what are Instant Apps? Instant Apps are Android apps that run without installation They provide users the ability to have rich native experiences at the tap of a URL In this example, our colleague Joyce sent us a URL for the New York Times crossword puzzle You tap on the URL, and it directly brings it up inside the New York Times crossword app No installation needed Now as a result of this, my product manager John, sends me a URL every morning with his timings Unfortunate consequence Anyway, so– now since Instant Apps are launched from URLs, they are discoverable from anywhere that you can put a URL Whether that’s a chat session with a friend or link in your search result Did you know that the White House was actually listed on Zillow? Now with installable apps, you’re probably used to users coming in through your front door So your launcher activity or your main activity But with Instant Apps, you just can launch into any experience that you have within your app So that improves the surface area for discovery Instant Apps are a mode of your existing app, not something separate They allow you to provide the exact same product experience that you provide in your current installable app They share the same package name, they have the same icon, and they have the same code bits So now that you know what Instant Apps are, and what user experiences they enable, let’s talk about a few key principles to keep in mind as you start building your Instant App You’ll see examples of these principles throughout the rest of this talk, and when you do it yourself So I’ll cover discoverability, security, and privacy, and performance Instant Apps are launched from URLs So the first step is to consider the experiences within your app, and make them URL addressable You can do this very easily with Android App Links App Links allows you to associate a domain with your app, and support specific paths against that domain within activities in your app The more of these paths you support, the more discoverable your app is Let’s talk about security and privacy With installable apps, apps get access to the user’s device when they go through an explicit– when the user goes through an explicit installation flow At that point, the user is granting your app access to your device You also have the ability to ask the user for permissions to access private data, like location Now with Instant Apps, they just launch from a URL So there’s no explicit installation flow, and hence no upfront consent For Instant Apps to maintain the same capabilities as installable apps, they use the runtime permissions API that allows them to get private data, like location or on-device resources like the camera We also provide user-resettable identifiers for Ad ID and Android ID But we limit Instant Apps when querying unique device identifiers, like IMEI and MAC address We also limit Instant Apps from querying what apps are installed on a user’s device,

and listening to system broadcast Finally, let’s talk about performance Instant apps are loaded and drawn on demand So the size of the binary has a huge impact to the user visible startup latency The smaller the binary, the faster it loads, the better the user experience So it’s very important to have small lightweight binaries to have a great Instant App experience We recommend starting your app on a very strict diet, zero fat Take out dead code, unused resources Look in your manifest for unused permissions, and your Gradle file for unnecessary libraries Many of our partners saw a huge improvement in their binary size with just this stuff You can then build your application into modules Remember, Instant Apps support multiple entry points So having modules that support each of these entry points, allows us to only load the module that’s needed for a given entry point With the ability to load more as the user goes through different flows within your app So to quickly summarize, three key principles to keep in mind while you build your Instant App Discoverability with Android App Links, privacy and security with the runtime permissions API, and performance with small modular binaries Now we worked with over 50 Early Access partners, who really helped us just define our developer experience Their level of engagement and their extremely valuable input is reflected in the quality of all components of our developer experience I’ll walk you through a few of these I’ll cover development tools, some new constructs that we’ve introduced, the project structure, as well as the publishing interface Many of you develop apps in Android Studio Android Studio 3.0 comes with Instant App support out of the box You can install the Instant Apps SDK through SDK manager And then you can build, run, test, and debug Instant Apps directly from the IDE You can also easily add URL entry points with the App Links Assistant that’s built directly in Android Studio Apart from on-device support, we’ve also enabled emulator support for you to do fast and easy local development We’ve introduced a new construct called the feature module The feature module is very similar to a library module in that it contains code resources and a manifest But feature modules build as APKs for your Instant App Our Gradle plugin will automatically build them as libraries for your installable app So you can use the exact same code base Now Instant Apps are built across multiple features So we’ve also introduced a Instant App module that builds the container to hold your feature APKs This is a zip file Now, installable apps are built as a single binary, the APK So the project structure can be done in a variety of ways Many of us have worked on apps that started small, and then it ended up being large, monolithic code bases under a single module I’ve always dreamed of the perfect modular structure And sometimes I’ve done the work, but there’s limited benefit to the actual binary size Now with Instant Apps, we need to load binaries on demand This is where our feature module comes in It allows you to extract out specific features into their own modules So you can set up your project to take the common code from your existing application module, and put it in a base feature module The base module is always loaded And then you can extract out specific features into their own modules That way, for a given entry point, we only load the base module and the corresponding feature module As the user goes through different flows within your app, we just load more of the feature modules within the same application context So now, you can have a project structure that builds both your Instant App and your installable app

directly from within a single Studio project Finally, when your Instant App is ready, you can use the Google Play console for publishing We’ve been enabled 3 publishing tracks– development, pre-release, and production– for you to roll out your Instant App in a phased manner So to quickly summarize our developer experience, you can set up Android Studio 3.0 with the Instant Apps SDK You can then introduce feature modules, and refactor your app into these feature modules such that we have a feature module for each entry point You can create a project structure that allows you to build both your Instant App and your installable app off the same Studio project And finally, when your app is ready, you can publish to the Google Play console So let’s get our hands dirty, and try this out At this time, I’d like to invite on stage, Anirudh Deawani Anirudh is our lead developer advocate for Instant Apps, and has worked with many of our partners to enable their Instant Apps experience Welcome, Anirudh ANIRUDH DEAWANI: Thank you, Shobana [APPLAUSE] SHOBANA RAVI: Next slide, please Still with the slides Still with the slides Can we switch back to the slides? Sorry, so Anirudh has an app called Banjara Banjara is a Hindi word for nomad The Banjara app is a tourist attractions app that gives you a list of attractions around you And for any given attraction, it gives you details Now the Banjara app is structured this way It has a top-level application module with two activities– one for the attractions list, and one for the details Each of these activities has their own fragments There’s some common code, such as integration Glide, Maps, some utilities The app also uses the runtime permissions API for location Now, today we’ll work on making Banjara Instant So the first thing to consider is what are the URL entry points into Banjara that makes sense? We have two entry points, one the list, and one the details We want to make both of them discoverable So we’d add two URL entry points One for the attraction’s list, and one for the details We’ll then refactor the existing application code into two feature modules The base feature module would contain the attraction’s list and the common code And the details feature module would then have the details experience Remember, the base module is always loaded And so the details feature module only needs to have the additional code So this is our target project structure We’ll get to it in three steps Step one, we’ll introduce URL entry points into our application We’ll do this with the App Links Assistant Step two, we’ll take our existing application module, and make it a single base feature module All the code is encapsulated within the feature module We can then introduce an Instant App module and an application module to build off this base feature module At this point, we’ll have our first functional Instant App Then step three, we’ll extract out the details experience from the base future module, and make it it’s own module So we’ve reach our target project structure in three steps Let’s try this out Step one, Anirudh, if we’re ready, can you show us our project structure? And then walk us through this step ANIRUDH DEAWANI: Absolutely So before we begin, let’s make sure we have the Instant App Development SDK installed So I have the SDK manager open And here you see, the development SDK is installed Just going to click OK All right, so now let’s just set up URL entry points for our app This is done by adding intent filters to your manifest To help us with the process, we are going to use the Android App Links Assistant tool And there, it opens as a panel on the right, and will guide us for the process of creating our entry points The first thing we want to do is map some URLs to our activities

So let’s set up some mappings So I’m going to use as my host And then setup main part from my attractions list activity I’ll repeat the step for HTTPS All right, now that we have the main part set up, we also will now set up the part for our details activity So again, the same host I use details, and choose details activity from the drop down box And then again, repeat the same step for HTTPS And there, we have our mapping set now There’s a Preview window here, which shows the manifest and the changes that we just did using the mapping editor All right, so the next step is then to add logic to handle our intent This is already done, because we are using existing code The next step is to create a digital access link file And then associate our website with our app package So I’m going to bring up the tool A couple of details, here You enter your site domain, you enter your application ID, and then you choose your sign-in key Now, I’m going to use the debug key But when you productionize your app, you’ll choose your release key, here I’ll now click on Digital– to generate my digital access link file Now this file basically tells us that our app is now mapped to our domain This is very important to claim ownership of your URLs This file now needs to be uploaded to a specific location on your server The location is here Once you are done uploading the file, we’ll click link and verify And this will make the association between your app and the domain All right, back to you, Shobana SHOBANA RAVI: OK So we’re done with step one And we now have two experiences within our app discoverable through URLs Let’s move on to step two We’ll now take our existing application module, and then put it in a base feature module So we’d have to rename our application to be a feature We’ll also change the Gradle file to not be com Android– com.Android.application and make it com.Android.feature Now, since all the code will be within the feature module, we can now introduce an application module and an Instant App module to build off the same feature module Each of them don’t need any code because they’re building off the existing model Let’s try that ANIRUDH DEAWANI: Sure So as you can see, on the left side, my project currently has one module That’s the Banjara-base, and this is an application model So what we are now trying to do is convert this into a feature model so all our code and resources are in this feature And then create two new top-level modules, an application model and an instant module And then we’ll include the feature as a dependency for those modules So I have my build Gradle file for my Banjara base module open It currently says com.Android.application I’m going to change this to com.Android.feature, this is the new plugin Now, all modular apps using the feature plugin are organized around the single base module Now, since this is our only module, we’ll tell the Gradle build to’s that this is our base module We are going to do this by setting the base feature property All right, now that we have our base module, we’ll create– let’s first create the application module So I’ll select New Module Choose Phone and Tablet And let’s call this Banjara App I’m just going to choose a package name that’s consistent with my other modules And I’ll select Add No Activity, because for now all our activities and all our code is in the feature module All right, the module is now created I’ll remove the path sources and resources for now And then, in my application manifest file,

I’ll remove the application tag, because this is going to get merged from our feature module So now, let’s look at the Gradle file for our newly created application module So the first thing I will do is use the same compile SDK and build to version that I’m using in my feature module Then remove the test dependencies And now, we want to include our feature module in our application module So right, now we have the feature module included There’s one final thing we need to do So let’s head over to our base build Gradle file again Now the base module is a very important module The Gradle build to’s look into the base model to figure out all of the features and the application in your project So we need to make our base model aware of our application model This will help with the manifest merging process, and will pull up the application ID to package the Instant App So this is done by using the application configuration All right, this is synced now Let’s try to compile I already have an emulator running, and let’s see, we got a little error here I’ll clean the project All right, the build is not successful So I have an emulator, here, running M. So let’s try to run our app, which is now using a feature module, which produces a feature APK, which produces a library file for our app So I’d select the app configuration, and then run There, our app is now running It uses runtime permissions for location And this is our list activity for a list of attractions I’ll bring up one of the details for one of the attractions, here All right, so now this is an installed app, because we used com.Drive Android.application So I’ll uninstall this app And we’ll now build an Instant App So to do that, I will create a new module and choose Instant App Let’s call this Banjara-InstantApp The module is created As you can see, on the left from the project structure, this is a very lightweight module There is no source, there are no resources It just has a build.Gradle file and it’s going to build just a container zip for our feature APKs So using the same compile and build tools as version And now, just as we did for our application model, I will include the feature model as a dependency Now, let’s try to build our Instant App

All right, the compilation is successful Now, before, we run this app, let’s take a look at our run configuration for the Instant App A habit here, as you can see in the launch options here Instead of using an activity, this is now using a URL So let’s switch it to the main, which maps to our list of attractions Apply OK And now, let’s run our first Instant App So this may take some time for the first time, when you try to run this Because it’s now setting up our device, it’s setting up our emulator for running Instant Apps Now our Instant App is running It uses the same runtime permission model, we didn’t make any changes to the code yet We have a list of attractions And then I bring up an attraction from the details activity So before I give it back to– [APPLAUSE] Thank you Before I hand it over back to Shobana, let’s quickly look at our build artifact from the Instant App project So here, as you can see, this is a zip file I’m going to use the APK analyser to inspect the zip file In the zip file, you can see, I have one feature APK It’s our base APK I can look down, and then drill down and look at my resource usage using the APK analyzer All right, back to you, Shobana SHOBANA RAVI: Great So we have our first functional Instant App 10 minutes So now, let’s move on to step three We’re going to extract out the details experience into it’s own feature module We’re doing this by introducing a new feature module, and just refactoring out of our existing base module into that feature module We’ll then have to update the application module and the Instant App module to now build from two feature modules So Anirudh can show us how to do that ANIRUDH DEAWANI: OK, let’s review our project structure Right now, we have three models Which is one is a feature module, Banjar base And then one application model And then Instant App module to wrap the feature model So let’s create a new feature model and defactor some code from our base model So I now use the new feature model template And call this Banjara details Following the same project structure, and the package naming scheme Now remember, feature modules are built just like libraries So they need to have a different package name, it cannot be the same as your application name Again, no activity to add We’ll refactor existing activities All right, our details model is now ready Let’s look at the build Gradle file So it automatically applied the plug-in com.Android.feature Let’s switch to the build to’s Now, when we created this module, Android Studio automatically added a dependency It says a dependency to Banjara base Remember what we said about modules there, the base module That all the feature models are organized around the single base module, and they need to extend the base module So because we already have a base model, Studio automatically applied the dependency to our base module And let’s take a look at our Gralde file for our base module Now you remember, we added the application configuration, here, to tell our base module about our app So it needs to pull down the package ID When we created the new details module,

Android Studio also added a feature configuration, which tells our base module about the other feature models in our project structure This is very important for manifest merging and the build process All right, so now we have two feature models created But we need to go back to our application and Instant App and include the new details module in the build I’m in my application right now I’ll add the details module, here And then the same for my Instant App All right, now that all the dependencies have been set up, let’s actually refactor some code into the details module So before we begin, I’ll create a package, where I need to place the new classes I’ll use the package name UI, this is where our classes are in the base module OK, I’m going to remove the path sources, again All right, now let’s actually go and get our classes that we need to refactor So we’ll move the details activity and the details fragment into the new module All right, the new classes, the details classes, are now on our details module We also need to move the activity declaration from the manifest file of the base module, where the classes were previously And bring that, the activity was previously, and then bring that to our feature module So this is my details activity Let’s add it to our manifest file for our details module We’ll just create an application tag to put the activities under it And there, let’s now compile the project All right, project compiled Now before we run this, let’s quickly inspect the container file again In my Banjara Instant App module, it’ll go to build outputs, and my zip file is here Now, when I inspect this using APK analyzer, I see now two feature APKs– my base feature APK and my details feature APK Now lets use our Instant App run configuration to run this And my app with two feature APKs is running [APPLAUSE] Thank you I’ll bring up an attraction Now this attraction details, were loaded from a different APK And before I hand it over to Shobana, I just want to show you in the launcher, here, we don’t have the Banjara app installed anymore, because we were running it as an Instant App But if we head over to the recents, we can see our Banjara app running All right, back to you Shobana SHOBANA RAVI: Thank you [APPLAUSE] Thank you So just to quickly summarize, how did we make Banjara Instant

We enabled URL entry points into our app We then created a base feature module with existing code And we extracted features out of the base module into their own feature module At the end, we had a single Studio project that you could build both the Instant App and the installable app Now, this was a simple sample app It’s likely that you’ll take a little longer than 15 minutes to make your own Instant App for a real world application We’ve heard from many of our partners as to how long it took And we found that it’s typical to take four to six weeks to build your Instant App You’ll spend the first part of that thinking through the product experience that you want to build in your Instant App Then identify the target project structure that’s perfect for your application And then there’s the refactoring effort to put code inside your base feature module, as well as into other feature modules And then you’ll spend some time trimming down each of these modules to be light and small size so they can be downloaded and run on the fly We have 50 Instant Apps live today I see a few of our Early Access partners over here Thank you and congratulations But we believe this is just the beginning We’re very excited to see what Instant Apps experiences you will build But we’re not done yet In the coming weeks and months, you’ll see huge improvements to the developer experience We’re focused on features that can enable additional binary size reduction That includes allowing your app to be sliced along device configurations, display densities Allowing commonly used libraries like app compact to be shared between Instant Apps And on the compression techniques to reduce over the air binary transmission On the tooling side, we’re introducing a new factoring tool that will make it really easy for you to modularize your code into features Additionally, we’re expanding Instant Apps to more devices and more countries to make sure your reach reaches all of Android Here’s some resources for you to get started Our Instant Apps web site has a lot of information around product But especially, it has a Getting Started guide for you to walk through the developer experience by yourself We’re also in the Instant Apps sandbox under Dome C, where you can come by and see some demos of our Early Access partners and their Instant Apps experience Immediately after this talk, we’re going to have a fireside chat with some of our Early Access partners so you can hear from them what their experiences were developing Instant Apps, and what benefits it’s brought to their applications We hope this talk was useful in jump starting your Instant App development Thank you so much for being here [APPLAUSE] [MUSIC PLAYING]