Skip to content
This repository has been archived by the owner on Sep 13, 2023. It is now read-only.

Update README.md #34

Merged
merged 4 commits into from
Jul 25, 2023
Merged
Changes from 1 commit
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
174 changes: 153 additions & 21 deletions README.md
Original file line number Diff line number Diff line change
@@ -1,26 +1,33 @@
[![](https://jitpack.io/v/spotify/openfeature-kotlin-sdk.svg)](https://jitpack.io/#spotify/openfeature-kotlin-sdk)
nickybondarenko marked this conversation as resolved.
Show resolved Hide resolved
<!-- markdownlint-disable MD033 -->
<p align="center">
<picture>
<source media="(prefers-color-scheme: dark)" srcset="https://raw.githubusercontent.com/open-feature/community/0e23508c163a6a1ac8c0ced3e4bd78faafe627c7/assets/logo/horizontal/white/openfeature-horizontal-white.svg">
<source media="(prefers-color-scheme: light)" srcset="https://raw.githubusercontent.com/open-feature/community/0e23508c163a6a1ac8c0ced3e4bd78faafe627c7/assets/logo/horizontal/black/openfeature-horizontal-black.svg">
<img align="center" alt="OpenFeature Logo">
</picture>
</p>

# OpenFeature Kotlin SDK
<h2 align="center">OpenFeature Kotlin SDKs</h2>

![Status](https://img.shields.io/badge/lifecycle-alpha-a0c3d2.svg)

What is OpenFeature?
## 👋 Hey there! Thanks for checking out the OpenFeature Kotlin SDK

### What is OpenFeature?

[OpenFeature][openfeature-website] is an open standard that provides a vendor-agnostic, community-driven API for feature flagging that works with your favorite feature flag management tool.

Why standardize feature flags?
Standardizing feature flags unifies tools and vendors behind a common interface which avoids vendor lock-in at the code level. Additionally, it offers a framework for building extensions and integrations and allows providers to focus on their unique value proposition.
### Why standardize feature flags?

This Kotlin implementation of an OpenFeature SDK has been developed at Spotify, and currently made available and maintained within the Spotify Open Source Software organization. Part of our roadmap is for the OpenFeature community to evaluate this implementation and potentially include it in the existing ecosystem of [OpenFeature SDKs][openfeature-sdks].
Standardizing feature flags unifies tools and vendors behind a common interface which avoids vendor lock-in at the code level. Additionally, it offers a framework for building extensions and integrations and allows providers to focus on their unique value proposition.

## Requirements
## 🔍 Requirements

- The Android minSdk version supported is: `21`.

Note that this library is intended to be used in a mobile context, and has not been evaluated for use in other type of applications (e.g. server applications).

## Usage

### Adding the library dependency
## 📦 Installation
nickybondarenko marked this conversation as resolved.
Show resolved Hide resolved

The Android project must include `maven("https://jitpack.io")` in `settings.gradle`.

Expand All @@ -37,22 +44,147 @@ api("com.github.spotify:openfeature-kotlin-sdk:[ANY_BRANCH]-SNAPSHOT")

This will get a build from the head of the mentioned branch.

### Resolving a flag
## 🌟 Features

- support for various backend [providers](https://openfeature.dev/docs/reference/concepts/provider)
- easy integration and extension via [hooks](https://openfeature.dev/docs/reference/concepts/hooks)
- bool, string, numeric, and object flag types
- [context-aware](https://openfeature.dev/docs/reference/concepts/evaluation-context) evaluation

## 🚀 Usage
fabriziodemaria marked this conversation as resolved.
Show resolved Hide resolved

```kotlin
// configure a provider and get client
OpenFeatureAPI.setProvider(
CustomProvider.initialise()
nickybondarenko marked this conversation as resolved.
Show resolved Hide resolved
)
val client = OpenFeatureAPI.getClient()

// get a bool flag value
client.getBooleanValue("boolFlag", default = false)

// get a bool flag value async
openFeatureClient
nickybondarenko marked this conversation as resolved.
Show resolved Hide resolved
.toAsync()
.observeBooleanValue(key, default)
.collect {
// do something with boolean
}

// get bool flag with compose
val myBoolProperty = openFeatureClient
nickybondarenko marked this conversation as resolved.
Show resolved Hide resolved
.toAsync()
.observeBooleanValue(key, default)
.collectAsState()
```

### Context-aware evaluation

Sometimes the value of a flag must take into account some dynamic criteria about the application or user, such as the user location, IP, email address, or the location of the server.
In OpenFeature, we refer to this as [`targeting`](https://openfeature.dev/specification/glossary#targeting).
If the flag system you're using supports targeting, you can provide the input data using the `EvaluationContext`.

<!-- TODO: code examples using context and different levels -->

### Events

Events allow you to react to state changes in the provider or underlying flag management system, such as flag definition changes, provider readiness, or error conditions.
Initialization events (`PROVIDER_READY` on success, `PROVIDER_ERROR` on failure) are dispatched for every provider.
Some providers support additional events, such as `PROVIDER_CONFIGURATION_CHANGED`.
Please refer to the documentation of the provider you're using to see what events are supported.

```kotlin
// to listen to PROVIDER_READY event
CoroutineScope(Dispatchers.IO).launch {
nickybondarenko marked this conversation as resolved.
Show resolved Hide resolved
awaitProviderReady()
// now provider is ready, read the properties
}
```

### Providers:

To develop a provider, you need to create a new project and include the OpenFeature SDK as a dependency.
This can be a new repository or included in [the existing contrib repository](https://github.com/open-feature/java-sdk-contrib) available under the OpenFeature organization.
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This is linking to the java sdk contrib now. We'll need to wait for the kotlin contrib location to be ready before adding it to the documentation

Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

There's another place in the readme that links to Kotlin repo (which isn't populated yet) - let's keep in mind to update these upon release.

Finally, you’ll then need to write the provider itself.
This can be accomplished by implementing the `Provider` interface exported by the OpenFeature SDK.

```kotlin
import dev.openfeature.sdk.*
class NewProvider(override val hooks: List<Hook<*>>, override val metadata: Metadata) : FeatureProvider {
override fun getBooleanEvaluation(
key: String,
defaultValue: Boolean,
context: EvaluationContext?
): ProviderEvaluation<Boolean> {
// resolve a boolean flag value
}

override fun getDoubleEvaluation(
key: String,
defaultValue: Double,
context: EvaluationContext?
): ProviderEvaluation<Double> {
// resolve a double flag value
}

override fun getIntegerEvaluation(
key: String,
defaultValue: Int,
context: EvaluationContext?
): ProviderEvaluation<Int> {
// resolve an integer flag value
}

override fun getObjectEvaluation(
key: String,
defaultValue: Value,
context: EvaluationContext?
): ProviderEvaluation<Value> {
// resolve an object flag value
}

override fun getStringEvaluation(
key: String,
defaultValue: String,
context: EvaluationContext?
): ProviderEvaluation<String> {
// resolve a string flag value
}

override suspend fun initialize(initialContext: EvaluationContext?) {
nickybondarenko marked this conversation as resolved.
Show resolved Hide resolved
// add context-aware provider initialisation
}

override suspend fun onContextSet(oldContext: EvaluationContext?, newContext: EvaluationContext) {
nickybondarenko marked this conversation as resolved.
Show resolved Hide resolved
// add necessary changes on context change
}

// Change NoOpProvider with your actual provider
OpenFeatureAPI.setProvider(NoOpProvider(), ImmutableContext())
val flagValue = OpenFeatureAPI.getClient().getBooleanValue("boolFlag", false)
}
```
Setting a new provider or setting a new evaluation context are asynchronous operations. The provider might execute I/O operations as part of these method calls (e.g. fetching flag evaluations from the backend and store them in a local cache). It's advised to not interact with the OpenFeature client until the `setProvider()` or `setEvaluationContext()` functions have returned successfully.

Please refer to our [documentation on static-context APIs](https://github.com/open-feature/spec/pull/171) for further information on how these APIs are structured for the use-case of mobile clients.

## ⭐️ Support the project

- Give this repo a ⭐️!
- Follow us on social media:
- Twitter: [@openfeature](https://twitter.com/openfeature)
- LinkedIn: [OpenFeature](https://www.linkedin.com/company/openfeature/)
- Join us on [Slack](https://cloud-native.slack.com/archives/C0344AANLA1)
- For more check out our [community page](https://openfeature.dev/community/)

## 🤝 Contributing

Interested in contributing? Great, we'd love your help! To get started, take a look at the [CONTRIBUTING](CONTRIBUTING.md) guide.

### Thanks to everyone that has already contributed

<a href="https://github.com/open-feature/kotlin-sdk/graphs/contributors">
<img src="https://contrib.rocks/image?repo=open-feature/kotlin-sdk" alt="Pictures of the folks who have contributed to the project" />
</a>

Made with [contrib.rocks](https://contrib.rocks).

### Providers
## 📜 License

To develop a provider, you need to create a new project and include the OpenFeature SDK as a dependency. You’ll then need to write the provider itself. This can be accomplished by implementing the `FeatureProvider` interface exported by the OpenFeature SDK.
[Apache License 2.0](LICENSE)

[openfeature-website]: https://openfeature.dev
[openfeature-sdks]: https://openfeature.dev/docs/reference/technologies/
[openfeature-website]: https://openfeature.dev