# A2uiRuntimeCatalog

Artifact: [androidx.a2ui.compose:compose-runtime](https://developer.android.com/jetpack/androidx/releases/a2ui-compose) [View Source](https://cs.android.com/search?q=file:androidx/a2ui/compose/runtime/A2uiRuntimeCatalog.kt+class:androidx.a2ui.compose.runtime.A2uiRuntimeCatalog) Added in [1.0.0-alpha02](https://developer.android.com/jetpack/androidx/releases/a2ui-compose#1.0.0-alpha02)


```
interface A2uiRuntimeCatalog
```

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*** ** * ** ***

A marker interface representing a registry of A2UI components and functions that can be utilized by the Jetpack Compose A2UI runtime layer.

This interface serves as an opaque token to provide catalogs to the runtime's `https://developer.android.com/reference/kotlin/androidx/a2ui/compose/runtime/package-summary#a2uiRuntimeMessageProcessor(kotlin.collections.List,kotlin.collections.List)` without tightly coupling the A2UI renderer runtime layer to specific visual UI framework implementations. This marker interface also allows hiding the A2UI core catalog type (`https://developer.android.com/reference/kotlin/androidx/a2ui/engine/catalog/A2uiCoreCatalog`) from the public API.

**Note for implementors:** Any concrete implementation of this interface provided to the runtime must also implement the underlying `https://developer.android.com/reference/kotlin/androidx/a2ui/engine/catalog/A2uiCoreCatalog` interface so that it can be successfully processed by the core data layer.