Referencing Google's V8 engine from a .NET app

Question

I'm building a .NET 3.5 application and have the need to evaluate JS code on the server - basically a user provided rule set that can work within a browser or on the server. Managed JS is not an option, because the JS code would be provided at runtime. Aptana's Jaxer is also not an option. So I was looking into using a build of the V8 engine within my app.

I built the source successfully into a DLL, but that DLL is not not a managed library and is not COM either. V8 is just plain C++.

Any ideas as to how to interop with this type of DLL in C#? Also, I'm open to other suggestions for SpiderMonkey or another JS engine.

Thanks in advance.

UPDATE:

I was able to use Ryan's solution. I just updated the references to the build for the latest from trunk. It worked great. Thanks Ryan.

Answer 1

I realize that this may not be an exact answer to your question, but I figured I would put my 2 cents worth in as I doubt to many people have tried this.

I got it to work by created a managed wrapper using mixed mode C++. There are other ways to do it, but I was going to attempt to make a full wrapper that could be used from any .Net language.

Getting the lib to compile in such a way that it could be included in a mixed mode project was a little bit of a challenge. I had to modify the runtime library (in the SConstruct file) used to /MD and /MDd so that it would be compatible with the /clr switch.

So far I have only simple scripts running as I have not implemented callbacks, custom methods, objects and such.

Here is a quick sample of what the usage looks like for one of my test apps:

V8DotNet.Shell shell = new V8DotNet.Shell();

shell.ExecuteScript(@"print('V8 version is: ' + version());");

It runs more complicated scripts like a base64 encoder fine as well. But for now I can only add custom items from the c++ side.

I am willing to provide more information + code if anyone is interested as I may not ever pick this project back up. But, I'm afraid it way to much code to go into a post here so we would have to find some other medium like google code or codePlex.

Edit:

---

OK, I've uploaded the code. I do have to put a disclaimer on this: The project is very early and I am an amateur at C++ at best so don't get your hopes up to much. Also, this project was created/done just after chrome was released so the version of v8 included may be old.

That said, here it is: http://ryanscook.com/Files/V8-DotNet.zip (21.5 MB)

In the package you'll find the following items of interest:

V8Net-Library\V8.Net\V8.Net.sln - This is the solution that has the managed C++ wrapper proj and a C# console app for testing.

Dependencies\V8 - This is my V8 code that I used to build the V8 lib.

Hope it helps!

Answer 2

From what I hear compiling it with IJW (Managed C++) should just work - but I may be really wrong, I have never touch MC++.

Answer 3

Ryan: Thanks for the help. I'd like to do a build with the /clr switch - like what you did. I have no experience whatsoever with Scons. Mind letting me know in more detail the changes you made to SConstruct file. Particularly, where you specify the /clr switch. Also, It looks like for a shared lib, /MD is already used.

Thanks in advance for your help.

Answer 4

Microsoft are building a real javascript - not "JScript" - runtime (along with IronPython, IronRuby, and VB10) on the CLR using the DLR, but I can't find any downloads or content for it. Perhaps this will arrive with C# 4?

Answer 5

Ryan, Your code was great but I need a way to add a FunctionTemplate that will call a C# function. On you demo you created the print function but it was declared as a native C++ function.

Thanks in advance for your help

Answer 6

Hey Ryan, is there anyway you can repost your project? It doesn't seem to be available any longer. Thanks.

Answer 7

Check out v8sharp. It supports executing JS inside of a .NET application. It also allows you to register .NET types with the v8 engine so that your JS code can interact with your .NET code. I am in the process of adding support for hooking function/delegate support.

Answer 8

You can try Javascript .NET:

http://javascriptdotnet.codeplex.com/

It lets you create a V8 context from .NET and register CLI objects in it so you can manipulate them and call members from the Javascript code. It compiles the Javascript at runtime.

Check it out.