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# [Android Components](../../../README.md) > Feature > Session
A component that connects an (concept) engine implementation with the browser session module.
A HistoryTrackingDelegate implementation is also provided, which allows tying together
an engine implementation with a storage module.
## Usage
### Setting up the dependency
Use Gradle to download the library from [maven.mozilla.org](https://maven.mozilla.org/) ([Setup repository](../../../README.md#maven-repository)):
```Groovy
implementation "org.mozilla.components:feature-session:{latest-version}"
```
### SwipeRefreshFeature
Sample code can be found in [Sample Browser app](https://github.com/mozilla-mobile/android-components/tree/main/samples/browser).
Class to add pull to refresh functionality to browsers. You should pass it a reference to a [`SwipeRefreshLayout`](https://developer.android.com/reference/kotlin/androidx/swiperefreshlayout/widget/SwipeRefreshLayout.html) and the SessionManager.
Your layout should have a `SwipeRefreshLayout` with an `EngineView` as its only child view.
```xml
<androidx.swiperefreshlayout.widget.SwipeRefreshLayout
android:id="@+id/swipeRefreshLayout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<mozilla.components.concept.engine.EngineView
android:id="@+id/engineView"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</androidx.swiperefreshlayout.widget.SwipeRefreshLayout>
```
In your fragment code, use `SwipeRefreshFeature` to connect the `SwipeRefreshLayout` with your `SessionManager` and `ReloadUrlUseCase`.
```kotlin
val feature = BrowserSwipeRefresh(sessionManager, sessionUseCases.reload, swipeRefreshLayout)
lifecycle.addObserver(feature)
```
`SwipeRefreshFeature` provides its own [`SwipeRefreshLayout.OnChildScrollUpCallback`](https://developer.android.com/reference/kotlin/androidx/swiperefreshlayout/widget/SwipeRefreshLayout.OnChildScrollUpCallback.html) and [`SwipeRefreshLayout.OnRefreshListener`](https://developer.android.com/reference/kotlin/androidx/swiperefreshlayout/widget/SwipeRefreshLayout.OnRefreshListener.html) implementations that you should not override.
### ThumbnailsFeature
Feature implementation for automatically taking thumbnails of sites. The feature will take a screenshot when the page finishes loading, and will add it to the `Session.thumbnail` property.
```kotlin
val feature = ThumbnailsFeature(context, engineView, sessionManager)
lifecycle.addObserver(feature)
```
If the OS is under low memory conditions, the screenshot will be not taken. Ideally, this should be used in conjunction with [SessionManager.onLowMemory](https://github.com/mozilla-mobile/android-components/blob/024e3de456e3b46e9bf6718db9500ecc52da3d29/components/browser/session/src/main/java/mozilla/components/browser/session/SessionManager.kt#L472) to allow free up some `Session.thumbnail` from memory.
```kotlin
// Wherever you implement ComponentCallbacks2
override fun onTrimMemory(level: Int) {
sessionManager.onLowMemory()
}
```
## License
This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this