Docs
News
Platform
Android Studio
Google Play
Android Jetpack
Docs
News
Platform
Android Studio
Google Play
Android Jetpack
Docs
News
More
Android Developers Blog
The latest Android and Google Play news for app and game developers.
Android Instant Apps: Best practices for managing download size
17 August 2017
Posted by Dmitry Malykhanov, Developer Relations Partner, Google Play
Android Instant Apps provides rich, native experiences at the tap of a web link. People can experience your app without upfront installation, enabling a higher level and quality of engagement.
However, to provide comparable latency of loading a mobile webpage, an instant app needs to be lean and well structured, so it can be downloaded and run quickly in response to a URL tap. In light of that, we encourage that the binary loaded in response any entry-point URL is as small as possible, with a maximum of 4MB. The smaller the binaries, the faster the instant app will load and the smoother the user experience.
This document will propose best practices for managing the application structure and binary size to enable a smooth instant app experience. These practices will also benefit your installable app.
Refactoring your codebase
The biggest binary size benefit comes from refactoring your app into
multiple feature modules
. Even if your current size and feature set don't require multiple features, we recommend designing for it, so you can quickly add more features in the future without affecting the binary size of existing features. We also highly recommend having a unified modular codebase to produce both installable and instant application binaries, as this will reduce the burden of maintaining separate projects and code and provide a cleaner project structure across both. Based on the experience of our early access partners, we believe this will have the largest impact to the binary size at download. However, it also requires the most investment.
To get to that end, you can start with a single (base) module and then refactor code by moving relevant portions to feature module(s). Note that you do not need to worry about the binary size while developing your instant app, as the size limit does not apply for locally built binaries. You can also publish your binary through the Play Developers Console to the
Development track
(special track for quick deployment of your instant app during development), where the size limit is 10MB. [
1
,
2
] The 4MB restriction is applied once your binary graduate out of the Development track.
Each feature module can have one (or more) entry points – activities – that correspond to a given URL. When splitting a single code base into multiple modules, you will have different entry points for different features, and the platform will load the relevant feature as needed. Remember, the total binary to be downloaded for any given entry point should be under 4MB, so the combined size of any feature module and the base module must be below 4MB.
It is advised to define the feature–activity–entry point mappings first, and then structure the refactoring effort towards reducing the binary size for each entrypoint..
Also consider how your libraries are included. If a specific feature module requires certain libraries they should be included in the feature module only, instead of being added in the base APK. This will reduce the size of the base module. For example, let's say you have an application that depends on libraries X, Y, and Z. Initially, you may pack all the libraries in the base module by placing all the dependencies in the base gradle.build file. But if only the code in the feature module requires library Z, it makes sense to move that dependency from the base module to the feature module.This works as long as no other feature modules depend on the same library. If multiple feature modules use the same library it definitely makes sense to keep it in the base module.
Lint checks
Many apps tend to acquire a lot of resources, and over a period of time, some of them are no longer used. Android Studio has useful built in lint check for unused resources. Press Alt+Ctrl+Shift+I (Cmd+Alt+Shift+I on Mac OS), type "unused resources" and start "Unused resources Android|Lint|Performance" inspection. It helps to reduce the size of the installable APK as well.
String resources
Similar to resources, pay attention to strings, not all of them may be in use, and typically the application size can be reduced significantly by removing unused string resources. If application supports multiple languages, you may want to reduce the number of localized resources, as it typically removes large chunks of the resources assets. This is especially important if the app supports only a few languages but uses AppCompat library, which includes messages in multiple languages. Use
resConfig
to select specific resources configurations only. Hint: typically you can use "
auto
" to restrict configurations pulled from third-party libraries to match the set of configurations defined in your project.
Switch to WebP
Significant reduction of the
drawable resources size
may be achieved by switching to
WebP images
instead of PNGs. Android Instant Apps supports all features of the WebP format (transparency, lossless, etc.) so there will be no loss in functionality. Keep in mind that application launcher icons must use PNG format, but it should not be a problem since projects normally keep those in mipmap- directories. If a backward compatible solution is required, you need to include the original PNG images in the APK module and it will
override WebP resources automatically
(main source set overrides all resources from AAR/feature module). [
4
]
Of course, going with vector drawables may let you save even more of the precious space, but using vector drawables will require a code change while the above mentioned trick with WebP images for the instant app and PNG images for the installable APK requires no code modifications.
Download assets at runtime
Finally, remember that technically there is no need to pack all the resources in the instant app APKs, as the application can download additional assets at run time. This approach also enables the app to download the required assets only. These modifications may require significant changes to the code base, but will also help you to reduce the size of the installable APK.
If shrinking resources does not bring your app feature modules size under the limit, it is time to look for the ways to reduce the code size.
Review native libraries
Some third-party libraries may include native code, which may not be used in the instant app at all. So the first step is to review the native libraries packaged within the APK and make sure the instant app has only those that are actually used. Remember to look into the compiled APK using
APK Analyzer
(Build -> APK Analyzer…) [
5
]
Review external libraries
Next review the list of all external libraries linked with the app's code. You may find some unexpected surprises courtesy of transitive dependencies. Transitive dependencies occur when the library your project relies upon depends on another library, which in turn may depend on yet another library. Sometimes those transitive dependencies may contain unexpected surprises such as libraries you do not need at all (i.e. a JSON processing library you never use in your code.) Please see "
Excluding transitive dependencies
" section in the Gradle User Guide for further details.
Android Studio has several useful tools for analyzing the external dependencies for the project. It always helps to start with the Project view:
The "Project" view shows a section called "External libraries", where you can see all the libraries used by the project including any transitive dependencies:
In order to further reduce the base feature size you may need to pay attention to the code dependencies and external libraries. Check the "Project" view and look for unused libraries that might be transitive dependencies the project does not need. Also look for libraries that provide the same functionality (e.g. multiple libraries for image loading/caching). [
4
]
You can also compare different builds with
APK Analyzer
tool, and it works with instant APKs, too.
Finally, review the list of transitive dependencies and exclude the ones you do not need. Use the following command to review the dependencies graph:
gradle -q :MODULE:dependencies --configuration compile
. Further details can be found in the
Gradle documentation
.
Other tips
Android Studio 3.0 includes the App Links Assistant tool, which can help to generate the necessary intent filters, and help in splitting the project into several modules. [
3
]
Once you got the instant app bundles under the size limit, it is the time to make sure the building process is up to date. Check that the application package and instant app APKs are signed using the "
APK Signature Scheme v2
". If you sign the APKs using the latest version of the SDK tools, everything should be done automatically. However, if you manually sign the build artifacts you need to avoid using jarsigner and switch to
apksigner
instead.
And a few useful tips for adapting the app's code to the instant runtime environment. Keep in mind that having a small branches of code for instant/installable applications, based on the
InstantApps.isInstantApp(...)
, should be fine and typically does not make the source code unreadable (unless you abuse it, of course). Also, when using share intents make sure the code does not explicitly enumerate applications installed on the device, instant app security model does not allow that. Simply use regular Intent.createChooser() to present the list of all possible actions to the user.
The level of effort of developing an instant app for an existing Android application varies across developers and is heavily dependent on how your application is organized today. For some, it will be easy as your project is already organized as multiple modules. However, for some, the focus will be on reducing the code and resource assets size, and we have introduced tools and Android platform features above to help you with that.
Hear from other developers using Android Instant Apps
Finally, check out these great posts by developers that have already built an instant app:
Buzzfeed
:
From Westinghouse to Android Instant apps, a BuzzFeed Journey
Realestate.com.au
:
Building the realestate.com.au Android Instant App
WillowTree
:
An introduction to Android Instant Apps
Jet.com
:
Make Your App Instant
Vimeo
:
Android Instant Apps, step-by-step: how Vimeo went about it
Ticketmaster
:
Ticketmaster Demonstrates Cutting Edge Android Instant Apps Technology at Google I/O
Domain
:
Making the Domain Android App Instant
Visit the Android Developers website to
get started with Android Instant Apps
and
check out more instant apps success stories
from other developers.
Labels
Android O
Android Studio
Design
Develop
Google Play
Archive
April 2019
(8)
March 2019
(11)
February 2019
(5)
January 2019
(6)
December 2018
(11)
November 2018
(9)
October 2018
(13)
September 2018
(5)
August 2018
(13)
July 2018
(9)
June 2018
(16)
May 2018
(16)
April 2018
(8)
March 2018
(8)
February 2018
(7)
January 2018
(9)
December 2017
(9)
November 2017
(13)
October 2017
(14)
September 2017
(12)
August 2017
(19)
July 2017
(11)
June 2017
(13)
May 2017
(21)
April 2017
(12)
March 2017
(14)
February 2017
(11)
January 2017
(12)
December 2016
(17)
November 2016
(16)
October 2016
(9)
September 2016
(6)
August 2016
(7)
July 2016
(12)
June 2016
(14)
May 2016
(16)
April 2016
(14)
March 2016
(8)
February 2016
(8)
January 2016
(9)
December 2015
(9)
November 2015
(13)
October 2015
(20)
September 2015
(15)
August 2015
(13)
July 2015
(9)
June 2015
(8)
May 2015
(10)
April 2015
(10)
March 2015
(12)
February 2015
(8)
January 2015
(3)
December 2014
(9)
November 2014
(13)
October 2014
(11)
September 2014
(6)
August 2014
(2)
July 2014
(9)
June 2014
(10)
May 2014
(4)
March 2014
(4)
February 2014
(3)
January 2014
(2)
December 2013
(3)
November 2013
(2)
October 2013
(7)
September 2013
(2)
August 2013
(5)
July 2013
(5)
June 2013
(4)
May 2013
(9)
April 2013
(3)
March 2013
(2)
February 2013
(3)
January 2013
(3)
December 2012
(5)
November 2012
(3)
October 2012
(3)
September 2012
(1)
August 2012
(1)
July 2012
(2)
June 2012
(5)
May 2012
(1)
April 2012
(5)
March 2012
(5)
February 2012
(5)
January 2012
(5)
December 2011
(7)
November 2011
(7)
October 2011
(5)
September 2011
(5)
August 2011
(3)
July 2011
(7)
June 2011
(2)
May 2011
(5)
April 2011
(6)
March 2011
(8)
February 2011
(8)
January 2011
(4)
December 2010
(8)
November 2010
(3)
October 2010
(4)
September 2010
(7)
August 2010
(6)
July 2010
(10)
June 2010
(11)
May 2010
(11)
April 2010
(2)
March 2010
(3)
February 2010
(2)
January 2010
(5)
December 2009
(7)
November 2009
(5)
October 2009
(5)
September 2009
(8)
August 2009
(2)
July 2009
(1)
June 2009
(2)
May 2009
(5)
April 2009
(12)
March 2009
(5)
February 2009
(8)
January 2009
(3)
December 2008
(3)
November 2008
(1)
October 2008
(4)
September 2008
(6)
August 2008
(4)
June 2008
(1)
May 2008
(5)
April 2008
(4)
March 2008
(5)
February 2008
(2)
January 2008
(5)
December 2007
(3)
November 2007
(5)
Feed
Newsletter
Android Developers
Google Play
Platform
Android Studio
Google Play
Android Jetpack
Docs
News
