FAQ

How can I incrementally adopt App Platform?

App Platform offers many recommendations and best practices and hardly enforces any principles, e.g. it’s possible to adopt the concept of the module structure without the Scope class or Presenters. Presenters can be used without Compose UI. This and the fact that App Platform is extensible allows for an incremental adoption. Apps can leverage the concepts and the framework without migrating all code at once.

For example, instead of going all in on the unidirectional dataflow, Android apps can start adopting Presenters and Renderers on an Activity by Activity or Fragment by Fragment basis. Today we recommend starting new App Platform code with Metro. Earlier, our Android app initially used Dagger 2 and Anvil as dependency injection framework and later made it interop with kotlin-inject-anvil before switching fully.

Can I use Dagger 2 or any other DI framework?

It depends, but likely yes. App Platform recommends Metro as the default DI framework because it supports Kotlin Multiplatform, verifies the dependency graph at compile time, and is the direction the framework docs and examples assume.

kotlin-inject-anvil remains supported as the alternative, especially for existing codebases or when you need compatibility with older App Platform examples.

Dagger 2 is more challenging, because it only supports Android and JVM application. Metro is the recommended default today, though App Platform started on Android with Dagger 2 and we first bridged those Dagger 2 components with kotlin-inject-anvil for interop.

How does App Platform compare to Circuit?

Circuit shares certain aspects with App Platform in regards to implementing the unidirectional dataflow, e.g. presenters and decoupling UI. How Screens with Circuit work vs how App Platform relies on composing presenters and renderers is different.

App Platform goes further and has feature that Circuit doesn’t provide, e.g. the module structure, the strong emphasis on fakes and robots.

At Amazon we built App Platform months before Circuit was released in 2022 and at this point there was no reason for us to migrate off of App Platform and to Circuit.

Help needed

Help from the community for a more in-depth comparison is needed.

Is App Platform used in production by Amazon?

App Platform was developed within the Amazon Delivery organization and is used to share code between several applications and platforms. Public products include the in-vehicle delivery app, Amazon Flex for Android and iOS and the Linux based Vision-Assisted Package Retrieval.