Flutter Csharp RPC

With this package we can execute C# code from Dart (Flutter) application via JSON-RPC protocol.

In run-time, we will create a C# child process and communicate with it via JSON-RPC protocol on the standard in/out (stdin/stdout) stream.

The JSON-RPC protocol let us invoke C# methods on the child process.

For example, we have the C# method:

public DateTime GetCurrentDateTime()
{
    return DateTime.Now;
}

And we call it from Dart code with the invoke method:

String currentDateTime = await csharpRpc.invoke(method: "GetCurrentDateTime");

We can also invoke method with array of parameters:

var sum = await csharpRpc.invoke<int>(method: "SumNumbers", params: [2, 3]);

And even send a typed request parameter:

var filesResult = await csharpRpc.invoke(
   method: "GetFilesInFolder",
   param: GetFilesInFolderRequest(folderPath: Directory.current.path)
);
var files = FilesInFolderResponse.fromJson(filesResult);

here we sending instance of request type GetFilesInFolderRequest, then we convert the result to a response type FilesInFolderResponse with the fromJson method, so we can have fully typed communication experience 🎉

📋 Dart/Flutter Setup

In your pubspec.yaml, add the csharp_rpc package as a new dependency with the following command:

PS c:\src\flutter_project> flutter pub add csharp_rpc

In your program code, create and use the CsharpRpc class to invoke methods:

import 'package:csharp_rpc/csharp_rpc.dart';

// create instance of CsharpRpc
var pathToCsharpExecutableFile = "<path_to_your_csharp_app>/CsharpApp.exe";

CsharpRpc csharpRpc = await CsharpRpc(pathToCsharpExecutableFile).start();

// invoke the C# method 'GetCurrentDateTime'
var currentDateTime = await csharpRpc.invoke(method: "GetCurrentDateTime");

📋 C# Setup

In your C# project, add the FlutterCsharpRpc Nuget package as a new dependency with the following command:

PS c:\src\flutter_project> dotnet add package FlutterCsharpRpc

In your program code, start the JSON-RPC server by calling the StartAsync method:

using FlutterCsharpRpc;

static async Task Main(string[] args)
{
    // your program setup (DI, service, etc) here...

    // start the JSON-RPC server
    await CsharpRpcServer.StartAsync(new Server());
}

public class Server
{
    public DateTime GetCurrentDateTime()
    {
        return DateTime.Now;
    }
}

⚡ Demo

See the full demo of Flutter and C# app that communicate between them.

🙏 Credit

This package based on Michael K Snead's article on medium: Flutter, C# and JSON RPC

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Tags: Csharp C# RPC flutter csharp flutter c# csharp ffi csharp json-rpc FlutterCsharpRpc StreamJsonRpc