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

If all you want to do is spin up a lightweight HTTP server while still programming with C# and .Net you should give Kayak a chance. It is a lightweight HTTP Server for C# and behaves kind of like node.js in that sense.

kayakhttp

Update:

If you are looking for a lightweight HTTP Server to handle web requests you have a couple alternatives today:

• ServiceStack (recommended)
• Microsoft WebAPI
• NancyFx

To my knowledge all the above work on some version of Mono, so you can still host them across both Windows and Unix based systems.

Answer 2

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 3

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.

Answer 4

.Net addons can be written, in short you write a regular native addon and add .Net calls via CLI/C++ calls to .Net dlls.

In practice you usually create a C# dll library which you then call from a CLI/C++ node addon project. There is a bit of delicacies such as making sure that the actual node add on definition file is compiled without CLR support so node can load it correctly.

You can check out: https://github.com/saary/node.net for an example of how this can be achieved.

Answer 5

The following answer is out of date, but still helpful for understanding of Node.js from first release
Node.js is now also available natively for Windows at nodejs.org. No cygwin requirement or otherwise.

First of all, at the moment there's no native Windows port of Node.js, there's only a cygwin version (but I suspect you already knew that).

There was a node module floating around somewhere at the GitHubs that provided wrappers for calling into native libraries, but iirc, that only worked with .so libs.

Therefore, if you want to use a C# DLL, you will first have to write a native Node.js extension as the interface:
https://www.cloudkick.com/blog/2010/aug/23/writing-nodejs-native-extensions/

From that extension you have to load the DLL and wrap the calls from Node.js to the C# code, that means you have to write some low level C/C++ code and convert C# values to V8 stuff.

I only have experience with C++ and V8, it's a bit hard to get started since the code examples are a bit sparse, also wrapping C++ classes is not that trivial. But I did wrote small JS game engine kind of thing, that uses a C++ OpenGL backend, it's unfinished (and there are hardly any comments) but it might give you some ideas.

Note: There are some projects in the wild that provide somewhat automatic generation of wrappers to V8, but those are C++ only.

So to conclude, I think it will be quite adventurous getting the C# wrappers to work, but it should be possible.

Answer 6

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 (npm i edge-js) from https://www.npmjs.com/package/edge-js

Answer 7

You might have some luck with this project, which is a port of Node.js to .NET. I haven't used it myself, but with a native .NET implementation you theoretically should be able to do what you need to.

You might also want to go the other direction and try to port (aka: recompile unless you're hooked deep into Windows) your C# game engine to Mono and see if you can then build wrappers off of that.

Answer 8

I know it's an old question, but wanted to throw in a current answer. With IIS 7.5 and .Net 4.x Websockets are supported, though use of the SignalR library will likely be the path of least resistance. It's similar to the socket.io library for NodeJS.

As to accessing .Net code via NodeJS, your best options are Edge.js, building a mixed native assembly with C/C++, exposing your .Net code either via a command line application (best to use pipes for input/output) or via a service (TCP or other).

I find Edge.js to be very limited, and not offer much over a piped console interface.. and feel that a service may be best for a more complex interface. At which point you may be best doing the rest of the project in .Net, unless you have an investment in NodeJS that supersedes said difficulties.