NTDLS.ReliableMessaging

What it is. A lightweight, high-performance TCP/IP messaging library for C#. Once connected, peers exchange two kinds of messages: fire-and-forget notifications (IRmNotification) and request/reply queries (IRmQuery<TReply>). Handlers can be convention-based (a class implementing IRmMessageHandler) or event-based. Optional built-in compression (Deflate or Brotli) and pluggable encryption round out the toolkit; CRC checks are applied to every packet automatically.

When to reach for it. You need a simple RPC backbone between your own services - backend to UI, service to service - without adopting gRPC or a message broker. It has been used as the communications layer for instant messaging, file transfer, proxy/tunneling and even a relational database server. Skip it if you need cross-language clients or a published wire protocol; this is designed for .NET-to-.NET talk.

Getting started

Define your message types:

public class MyNotification : IRmNotification
{
    public string Message { get; set; }

    public MyNotification(string message)
    {
        Message = message;
    }
}

public class MyQuery : IRmQuery<MyQueryReply>
{
    public string Message { get; set; }

    public MyQuery(string message)
    {
        Message = message;
    }
}

public class MyQueryReply : IRmQueryReply
{
    public string Message { get; set; }

    public MyQueryReply(string message)
    {
        Message = message;
    }
}

Start a server with a convention-based handler whose method signatures match your message types:

var server = new RmServer();
server.AddHandler(new HandlerMethods());
server.Start(31254);

internal class HandlerMethods : IRmMessageHandler
{
    public void MyNotificationReceived(RmContext context, MyNotification notification)
    {
        Console.WriteLine($"Server received notification: {notification.Message}");
    }

    public MyQueryReply MyQueryReceived(RmContext context, MyQuery query)
    {
        return new MyQueryReply("This is the query reply from the server.");
    }
}

Then connect a client, send notifications, and issue a query that blocks until the reply arrives:

var client = new RmClient();
client.Connect("localhost", 31254);

client.Notify(new MyNotification("Hello from the client."));

var reply = client.Query(new MyQuery("What time is it?"));
Console.WriteLine($"Client received query reply: '{reply.Message}'");

Async variants NotifyAsync() and QueryAsync() are available, and compression/encryption attach via SetCompressionProvider() / SetCryptographyProvider() on both ends.

NuGet: NTDLS.ReliableMessaging