What replaces WCF in .Net Core?

I am used to creating a .Net Framework console application and exposing a Add(int x, int y) function via a WCF service from scratch with Class Library (.Net Framework). I then use the console application to proxy call this function within the server.

However if I use Console App (.Net Core) and a Class Library (.Net Core) the System.ServiceModel is not available. I have done some Googling but I haven't figured out what "replaces" WCF in this instance.

How do I expose a Add(int x, int y) function within a class library to a console application all within .Net Core? I see System.ServiceModel.Web, and since this is trying to be cross platform do I have to create a RESTful service?

Solution 1:

You can use gRPC for hosting web services inside .NET core application.

Introduction

1. gRPC is a high performance, open source RPC framework initially developed by Google.
2. The framework is based on a client-server model of remote procedure calls. A client application can directly call methods on a server application as if it was a local object.

Example

Server Code

class Program
{
    static void Main(string[] args)
    {
        RunAsync().Wait();
    }

    private static async Task RunAsync()
    {
        var server = new Grpc.Core.Server
        {
            Ports = { { "127.0.0.1", 5000, ServerCredentials.Insecure } },
            Services =
            {
                ServerServiceDefinition.CreateBuilder()
                    .AddMethod(Descriptors.Method, async (requestStream, responseStream, context) =>
                    {
                        await requestStream.ForEachAsync(async additionRequest =>
                        {
                            Console.WriteLine($"Recieved addition request, number1 = {additionRequest.X} --- number2 = {additionRequest.Y}");
                            await responseStream.WriteAsync(new AdditionResponse {Output = additionRequest.X + additionRequest.Y});
                        });
                    })
                    .Build()
            }
        };

        server.Start();

        Console.WriteLine($"Server started under [127.0.0.1:5000]. Press Enter to stop it...");
        Console.ReadLine();

        await server.ShutdownAsync();
    }
}

Client Code

class Program
{
    static void Main(string[] args)
    {
        RunAsync().Wait();
    }

    private static async Task RunAsync()
    {
        var channel = new Channel("127.0.0.1", 5000, ChannelCredentials.Insecure);
        var invoker = new DefaultCallInvoker(channel);
        using (var call = invoker.AsyncDuplexStreamingCall(Descriptors.Method, null, new CallOptions{}))
        {
            var responseCompleted = call.ResponseStream
                .ForEachAsync(async response => 
                {
                    Console.WriteLine($"Output: {response.Output}");
                });

            await call.RequestStream.WriteAsync(new AdditionRequest { X = 1, Y = 2});
            Console.ReadLine();

            await call.RequestStream.CompleteAsync();
            await responseCompleted;
        }

        Console.WriteLine("Press enter to stop...");
        Console.ReadLine();

        await channel.ShutdownAsync();
    }
}

Shared Classes between Client and Server

[Schema]
public class AdditionRequest
{
    [Id(0)]
    public int X { get; set; }
    [Id(1)]
    public int Y { get; set; }
}

[Schema]
public class AdditionResponse
{
    [Id(0)]
    public int Output { get; set; }
}

Service descriptors

using Grpc.Core;
public class Descriptors
{
    public static Method<AdditionRequest, AdditionResponse> Method =
            new Method<AdditionRequest, AdditionResponse>(
                type: MethodType.DuplexStreaming,
                serviceName: "AdditonService",
                name: "AdditionMethod",
                requestMarshaller: Marshallers.Create(
                    serializer: Serializer<AdditionRequest>.ToBytes,
                    deserializer: Serializer<AdditionRequest>.FromBytes),
                responseMarshaller: Marshallers.Create(
                    serializer: Serializer<AdditionResponse>.ToBytes,
                    deserializer: Serializer<AdditionResponse>.FromBytes));
}

Serializer/Deserializer

public static class Serializer<T>
{
    public static byte[] ToBytes(T obj)
    {
        var buffer = new OutputBuffer();
        var writer = new FastBinaryWriter<OutputBuffer>(buffer);
        Serialize.To(writer, obj);
        var output = new byte[buffer.Data.Count];
        Array.Copy(buffer.Data.Array, 0, output, 0, (int)buffer.Position);
        return output;
    }

    public static T FromBytes(byte[] bytes)
    {
        var buffer = new InputBuffer(bytes);
        var data = Deserialize<T>.From(new FastBinaryReader<InputBuffer>(buffer));
        return data;
    }
}

Output

Sample client output

Sample Server output

References

1. https://blogs.msdn.microsoft.com/dotnet/2018/12/04/announcing-net-core-3-preview-1-and-open-sourcing-windows-desktop-frameworks/
2. https://grpc.io/docs/
3. https://grpc.io/docs/quickstart/csharp.html
4. https://github.com/grpc/grpc/tree/master/src/csharp

Benchmarks

1. http://csharptest.net/787/benchmarking-wcf-compared-to-rpclibrary/index.html

Solution 2:

WCF is not supported in .NET Core since it's a Windows specific technology and .NET Core is supposed to be cross-platform.

If you are implementing inter-process communication consider trying the IpcServiceFramework project.

It allows creating services in WCF style like this:

1. Create service contract

   public interface IComputingService
   {
       float AddFloat(float x, float y);
   }
   

2. Implement the service

   class ComputingService : IComputingService
   {
       public float AddFloat(float x, float y)
       {
           return x + y;
       }
   }
   

3. Host the service in Console application

   class Program
   {
       static void Main(string[] args)
       {
           // configure DI
           IServiceCollection services = ConfigureServices(new ServiceCollection());
   
           // build and run service host
           new IpcServiceHostBuilder(services.BuildServiceProvider())
               .AddNamedPipeEndpoint<IComputingService>(name: "endpoint1", pipeName: "pipeName")
               .AddTcpEndpoint<IComputingService>(name: "endpoint2", ipEndpoint: IPAddress.Loopback, port: 45684)
               .Build()
               .Run();
       }
   
       private static IServiceCollection ConfigureServices(IServiceCollection services)
       {
           return services
               .AddIpc()
               .AddNamedPipe(options =>
               {
                   options.ThreadCount = 2;
               })
               .AddService<IComputingService, ComputingService>();
       }
   }
   

4. Invoke the service from client process

   IpcServiceClient<IComputingService> client = new IpcServiceClientBuilder<IComputingService>()
       .UseNamedPipe("pipeName") // or .UseTcp(IPAddress.Loopback, 45684) to invoke using TCP
       .Build();
   
   float result = await client.InvokeAsync(x => x.AddFloat(1.23f, 4.56f));
   

Solution 3:

It seems, that there will be a CoreWCF project maintained by .NET Foundation with Microsoft support.

More details at Welcoming Core WCF to the .NET Foundation

Initially only netTcp and http transport will be implemented.

Solution 4:

WCF does many things; it is an easy way to remote procedure calls between two applications (processes) on one machine, using named pipes; it can be a high volume internal client-server communication channel between .NET components, using binary serialization over TCPIP; or it can provide a standardised cross-technology API, e.g. via SOAP. It even has support for things like asynchronous messaging, via MSMQ.

For .NET Core, there are different replacements based on the purpose.

For cross-platform API, you would replace this with a REST service using ASP.NET.

For inter-process connections, or client-server connection, gRPC would be good, with an excellent answer given by @Gopi.

So the answer to "What replaces WCF" depends on what you are using it for.

Solution 5:

There is a community repo https://github.com/CoreWCF/CoreWCF that implements some parts of WCF. You can use it to support some simple WCF services. However not all features are supported.