msstorelib

Kotlin/JVM library for Microsoft Store license info and in-app purchases.

The JVM calls a small C++/WinRT DLL (msstore_winrt.dll) via Java FFM (Panama).

Features

• Query the Store license JSON (ExtendedJsonData).
• Parse a stable subset of license fields into Kotlin data classes.
• Trigger the Store purchase UI for add-ons or other in-app products.
• Native DLL loading with override, app-local, system-path, and embedded fallback resolution.

Install from Maven Central

repositories {
    mavenCentral()
}

dependencies {
    implementation("de.stefan-oltmann:msstorelib:0.2.0")
}

Usage

License info

import de.stefan_oltmann.msstore.MsStore
import de.stefan_oltmann.msstore.MsStoreLicenseException

fun main() {

    try {

        val json = MsStore.getLicenseJson()
        println("Raw JSON from Store:")
        println(json)

        val info = MsStore.getLicenseInfo()
        println()
        println("Parsed summary:")
        println("productId  = ${info.productId}")
        println("skuId      = ${info.skuId}")
        println("isActive   = ${info.isActive}")
        println("isTrial    = ${info.isTrial}")
        println("expiration = ${info.expiration}")

        if (info.productAddOns.isNotEmpty())
            println("addOns     = ${info.productAddOns.size}")

    } catch (ex: MsStoreLicenseException) {
        System.err.println("Store license query failed: ${ex.message}")
        System.err.println("Make sure the app is Store-packaged and msstore_winrt.dll is built.")
        throw ex
    }
}

In-app purchase

import de.stefan_oltmann.msstore.MsStore
import de.stefan_oltmann.msstore.MsStorePurchaseStatus

val status = MsStore.requestPurchase("9p9hdfltk63l")

when (status) {
    MsStorePurchaseStatus.Succeeded -> {
        /* Purchase was successful */
    }
    MsStorePurchaseStatus.AlreadyPurchased -> {
        /* License already exists */
    }
    else -> {
        /* Show error */
    }
}

The native layer assigns the current foreground window as the owner HWND for Store modal UI. Ensure your app has a focused window when requesting purchases.

API model types

• MsStoreLicenseInfo (app license summary)
• MsStoreAddOnLicenseInfo (add-on license entries)
• MsStorePurchaseStatus (purchase result status)

Error handling

• MsStoreLicenseException is thrown when the native call fails.
• The native layer stores the last error string, exposed in Kotlin via MsStoreNative.getLastError().

Requirements

• Windows 10/11
• App packaged with MSIX and a Microsoft Store identity
• Product associated in Partner Center
• Using Java 25 or higher

If these requirements are not met, Store APIs can return empty results or errors.

Native DLL loading

Resolution order:

1. -Dmsstore.winrt.path=...
2. msstore_winrt.dll in hosting app folder (next to app/JAR)
3. System library path (System.loadLibrary("msstore_winrt"))
4. Extract embedded resource windows-x86_64/msstore_winrt.dll to versioned cache and load it

Extraction is only attempted when steps 1-3 fail. Cache path format: <java.io.tmpdir>/msstorelib-native/<LIB_VERSION>/windows-x86_64/msstore_winrt.dll

LIB_VERSION is generated at build time (from project version / git-versioning). This means extraction runs once per library version, not on every start.

Override path example:

-Dmsstore.winrt.path=C:\path\to\msstore_winrt.dll

Local DLL build

For local builds you need to install these two dependencies.

CMake:

winget install --id Kitware.CMake -e --accept-source-agreements --accept-package-agreements

Visual Studio 2022 Build Tools (C++ workload):

winget install --id Microsoft.VisualStudio.2022.BuildTools -e --accept-source-agreements --accept-package-agreements --override "--quiet --wait --norestart --add Microsoft.VisualStudio.Workload.VCTools --includeRecommended"

If winget is unavailable, use manual installers:

• CMake: https://cmake.org/download/
• Visual Studio Build Tools: https://aka.ms/vs/17/release/vs_BuildTools.exe

Then run: .\gradlew buildNativeLib

This builds the DLL and copies it to: src/main/resources/windows-x86_64/msstore_winrt.dll

Official docs

• Get license info for apps and add-ons: https://learn.microsoft.com/windows/uwp/monetize/get-license-info-for-apps-and-add-ons
• Store JSON schema reference (ExtendedJsonData): https://learn.microsoft.com/windows/uwp/monetize/data-schemas-for-store-products
• StoreContext API: https://learn.microsoft.com/uwp/api/windows.services.store.storecontext