Windows

Windows

The package supports React Native Windows 0.84+ with the New Architecture
(Fabric / WinAppSDK, cpp-app template). The JS API and the C++ protocol core
are the same as on iOS and Android. Only the TCP transport is Windows-specific.

Requirements

• Windows 10 22H2+ or Windows 11.
• Node.js 22.11 or newer.
• Visual Studio 2022 (MSVC v143) or 2026 (MSVC v145) with the “Desktop development with C++” and “Windows application development” workloads.
• Windows SDK 10.0.26100.
• react-native-windows 0.84+ and react-native-nitro-modules in the app.

RNW’s rnw-dependencies.ps1 script (in node_modules/react-native-windows/scripts) installs missing tools.

Setup

Install the package, its C++ Kit, the Nitro host and Nitro. The host, @padosoft/react-native-nitro-windows, is not published yet: link it from a react-native-support checkout (file:…/packages/react-native-nitro-windows), as example-windows does.

npm install @padosoft/react-native-ecr17 @padosoft/ecr17-kit @padosoft/react-native-nitro-windows react-native-nitro-modules

Add the host’s autolink helper to the app’s react-native.config.js:

const { windowsAppDependencies } = require("@padosoft/react-native-nitro-windows");

module.exports = {
  dependencies: windowsAppDependencies(),
};

Link and build:

npx react-native autolink-windows
npx react-native run-windows

Client code is unchanged:

import { createEcr17Client } from "@padosoft/react-native-ecr17";

const client = createEcr17Client({
  host: "192.168.1.100",
  port: 10000,
  terminalId: "00000000",
  cashRegisterId: "00000001",
});

How it works

• The app’s Nitro host, @padosoft/react-native-nitro-windows (not published yet), implements NitroModules.install(). It registers this package’s HybridObjects, then runs Nitro’s install() with RNW’s JSI runtime and CallInvoker. This package ships no Windows project: it declares its C++ in package.json (nitroWindows), and the host compiles it together with the Kit’s.
• Ecr17Client is the shared C++ HybridEcr17Client over the Kit’s Ecr17Client, the same code as on iOS and Android.
• Ecr17Transport is HybridEcr17TransportWindows, the Nitro face of the Kit’s C++ WinsockTransport (iOS uses Swift, Android uses Kotlin).
• The host compiles Nitro’s C++ runtime from the app’s node_modules/react-native-nitro-modules, once for every Nitro package in the app.
• The host also generates the <NitroModules/…> header shims MSVC needs, because MSVC has no header map.

Every Nitro package that supports Windows goes through the same host, so several of them can live in one app.

Payment safety on Windows

The Winsock transport keeps the same contract as the Kotlin one:

• isConnected() is a write-free, non-destructive probe (an instant select poll plus recv with MSG_PEEK). A socket the terminal closed between transactions is detected before a command is sent, so the client reconnects first.
• The probe never writes to the terminal and never consumes a protocol byte.
• onDisconnect fires once per unexpected drop and never for a caller’s disconnect().

Example app and tests

example-windows/ in the repository is a small RNW console app (status, totals, last result, one payment). It is a separate npm project, because RNW 0.84 pins React Native 0.84.1 while the Expo example uses a newer React Native.

The Kit’s tests (cmake -S kit) run the Winsock transport against a loopback server on Windows, with no Nitro or React Native Windows needed: drop detected before send, no bytes written by the probe, none consumed, one disconnect signal per drop, and a fast probe. Windows has no CI job, so run it and the example-windows build locally after native changes.

Status

The Windows build, the transport tests and a runtime smoke test are verified locally. The smoke test ran in the deployed example app against a fake terminal: Nitro installed, the client connected, a status frame went out, and the drop was detected after the terminal closed the socket. The integration has not been verified against a physical terminal yet. Test with small amounts on a test terminal before production use.