GW2APIClient

A Kotlin Multiplatform library for working with the official Guild Wars 2 API.

The core library is fully written in common Kotlin code. Prebuilt binaries are available for JVM (Java 11 or later), JS, Wasm, and several native targets.¹

Usage

GW2APIClient provides low-level access to the data provided by Guild Wars 2's API. It does not provide higher-level abstractions, visualizations or analytical functionality but may be used to build such tools.

GW2APIClient consists of two primary modules:

API Types

The api-types module provides type-safe definitions for the objects returned by the Guild Wars 2 API. kotlinx.serialization is used for built-in support for serialization from and to JSON.

A type definition for the identity field exposed by the MumbleLink mechanism is also available. Check out GW2ML for reading MumbleLink data.

API Client

The api-client module provides definitions for the endpoints available as part of the Guild Wars 2 API.

Getting Started

To get started with the API client, it is necessary to also pick an implementation module:

• api-client-jdk11 contains an implementation using Java's HttpClient.
• api-client-ktor contains an implementation using Ktor.

Once the implementation module is chosen, the API client can be built using the functions exposed by JdkGw2ApiClientFactory or KtorGw2ApiClientFactory respectively:

val client = Gw2ApiClient()

Implementing Caching

To configure an API client to use a cache, a CacheAccess implementation can be provided when building an API client:

val client = buildGw2ApiClient {
    cacheAccess = MyCacheAccess()
}

This library does not provide a cache implementation. Thus, by default no caching is configured.

Configuring Rate Limiting

To configure an API client to perform client-side rate limiting, a RateLimiter can be provided when building an API client:

val client = buildGw2ApiClient {
    rateLimiter = MyRateLimiter()
}

By default, API clients are configured to use a TokenBucketRateLimiter with a bucket size of 300 and a refill duration of 1 minute. This configuration roughly matches the rate limiting behavior of the official API and should prevent requests from running into rate limits.

However, as the same rate limit applies to all clients on a single IP address, it may be desirable to adjust the rate limiter to match the specific use case.

Configuring Requests

Endpoints may return localized data. For example, the /v2/items endpoint may return item names in different languages. By default, all requests will return English information. To request localized data for a different language, the RequestCustomizer may be used:

val request = gw2v2ItemsByPage(page = 0, pageSize = 10) {
    language = Language.GERMAN
}

Similarly, some endpoints require authentication and an API key has to be provided:

val request = gw2v2Account() {
    apiKey = "..."
}

It is also possible to apply a default configuration to all requests executed by an API client:

val client = buildGw2ApiClient {
    configureRequests {
        apiKey = "..."
        language = Language.GERMAN
    }
}

Example

Retrieving the Build ID

The following example demonstrates how to execute a request against the Guild Wars API to retrieve the current build ID:

suspend fun main() {
    val client = Gw2ApiClient()
    val buildId = client.executeAsync(gw2v2Build()).dataOrNull?.id ?: error("Failed to fetch build ID.")

    println("Build ID: $buildId")    
}

Retrieving Items

The following example demonstrates one possible way to retrieve multiple items. First, the IDs of all items are fetched. Those IDs are then chunked into groups of up to 200 IDs each (as this is the maximum number of items that can be fetched in one call). Next, requests to fetch the first 10 chunks are started asynchronously. Finally, the results are combined and printed to the console:

suspend fun main() {
    val client = Gw2ApiClient()
    val itemIds = client.executeAsync(gw2v2ItemsIds()).dataOrNull ?: error("Failed to fetch item IDs.")

    val items = coroutineScope {
        itemIds
            .chunked(size = 200)
            .take(10)
            .map { ids ->
                async { client.executeAsync(gw2v2ItemsByIds(ids)).dataOrNull }
            }
            .awaitAll()
            .filterNotNull()
            .flatten()
    }

    for (item in items) {
        println("[${item.id}] ${item.name}")
    }
}

Supported platforms

The following targets are supported by this library:

Target platform	Target preset
Kotlin/JVM (can also be used on Android)	jvm
Kotlin/JS	js
iOS	iosArm64, iosX64, iosSimulatorArm64
watchOS	watchosArm32, watchosArm64, watchosX64, watchosSimulatorArm64
tvOS	tvosArm64, tvosX64, tvosSimulatorArm64
macOS	macosArm64, macosX64
Linux	linuxArm64, linuxX64
Windows	mingwX64

Building from source

Setup

This project uses Gradle's toolchain support to detect and select the JDKs required to run the build. Please refer to the build scripts to find out which toolchains are requested.

An installed JDK 1.8 (or later) is required to use Gradle.

Generating Endpoints

The api-generator is used to generate the types and endpoint definitions for this library. Head over to its repository to learn more about Guild Wars 2's API.

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1. We aim to provide prebuilt libraries for all native targets supported by Ktor. Despite that, some targets may be missing as target support may change over time. In case something is missing, please make sure to let us know. ↩