Merge pull request #34 from spotify/readme

Update README.md
spotify · Jul 25, 2023 · ccfc81a · ccfc81a
2 parents 5da99a5 + b9ae141
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@@ -1,26 +1,35 @@
-[![](https://jitpack.io/v/spotify/openfeature-kotlin-sdk.svg)](https://jitpack.io/#spotify/openfeature-kotlin-sdk)
+<!-- 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)
+![Status](https://img.shields.io/badge/lifecycle-alpha-a0c3d2.svg) [![](https://jitpack.io/v/spotify/openfeature-kotlin-sdk.svg)](https://jitpack.io/#spotify/openfeature-kotlin-sdk)
+
+## 👋 Hey there! Thanks for checking out the OpenFeature Kotlin SDK
+
+### What is OpenFeature?
 
-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
+## 📦 Installation
 
-### Adding the library dependency
+### Jitpack
 
 The Android project must include `maven("https://jitpack.io")` in `settings.gradle`.
 
@@ -37,22 +46,135 @@ 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
+### Maven
+
+Installation via Maven Central is currently WIP
+
+## 🌟 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
+
+```kotlin
+    // configure a provider and get client
+    OpenFeatureAPI.setProvider(customProvider)
+    val client = OpenFeatureAPI.getClient()
+
+    // get a bool flag value
+    client.getBooleanValue("boolFlag", default = false)
+
+    // get a bool flag value async
+    coroutineScope.launch {
+        WithContext(Dispatchers.IO) {
+            client.awaitProviderReady()
+        }
+        client.getBooleanValue("boolFlag", default = false)
+    }
+```
+
+### 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
-import dev.openfeature.sdk.*
+    OpenFeatureAPI.eventsObserver()
+        .observe<OpenFeatureEvents.ProviderReady>()
+        .collect {
+            // do something once the provider is ready
+        }
+```
+
+### 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 available under the OpenFeature organization.
+Finally, you’ll then need to write the provider itself.
+This can be accomplished by implementing the `Provider` interface exported by the OpenFeature SDK.
 
-// Change NoOpProvider with your actual provider
-OpenFeatureAPI.setProvider(NoOpProvider(), ImmutableContext())
-val flagValue = OpenFeatureAPI.getClient().getBooleanValue("boolFlag", false)
+```kotlin
+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 fun initialize(initialContext: EvaluationContext?) {
+        // add context-aware provider initialisation
+    }
+
+    override fun onContextSet(oldContext: EvaluationContext?, newContext: EvaluationContext) {
+        // add necessary changes on context change
+    }
+
+}
 ```
-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