Using a .NET DLL in Node.js / serverside javascript

Question

I have a pet project that is an online game, the entire game engine is written in C# and I would like to know if there is anyway I can call the functions of this existing assembly (.dll) from a solution built using Node.JS, Socket.IO, Express etc?

The game engine itself is pretty complete; tested and robust. I am hoping there is some neat way of exposing its functionality without too much overhead.

UPDATE:

To answer my own question a little.. I have ended building my own web socket server (based on the most current web socket protocol document). It is written in C# and compiled using Mono so that it can be hosted on a Linux box running mono and therefore (with a few tweaks) I can use my existing game engine.

UPDATE 2 A project that does exactly what I was originally looking for now exists - http://tjanczuk.github.io/edge/#/

UPDATE 3 Edge.js supporting node's last versions and .net core with a new edge-js package.

Support for Node.Js 6.x, 7.x, 8.x, 9.x, 10.x, 11.x Support for .NET Core 1.0.1 - 2.x on Windows/Linux/macOS. Support for Mono runtime 4.8.x - 5.x.

Can be installed from https://www.npmjs.com/package/edge-js

Answer 1

Check out the edge.js project I started (http://tjanczuk.github.com/edge). It provides a mechanism for running .NET and node.js code in-process. Edge.js allows you to call .NET code from node.js and node.js code from .NET. It marshals data between .NET and node.js as well as reconciles the threading models between multi-threaded CLR and single threaded V8.

Using edge.js you can access islands of pre-existing .NET code from node.js, which seems to match your scenario.

Answer 2

I've been recently faced with the same challenge (requirement to call C# code from node.js javascript). I had 1000s of lines of complex C# code that I really didn't like to port to javascript.

I solved if as follows.

• The relevant C# code is basically 1-2 classes in a DLL assembly
• Defined a COM interface which is a subset of the C# class's interface and implemented that interface in the C# class. Thus, the DLL became an in-process COM server.
• Implemented a node.js extension DLL that instantiates my C# COM class using standard Win32 COM API and routes method calls from node.js javascript to C# code using the COM interface.

This solves the problem if one only wants to make calls in one direction. I also had the requirement to make calls from C# to javascript. This is a lot harder. One has to:

• Implement a COM object in the node.js extension DLL (ATL helps here)
• Pass an interface reference of this COM object to C# code (COM Interop)
• Route calls via the COM object to V8 objects in node.js

Maybe if I have some extra time, I might make an example project out of this.