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Call Function from DLL loaded in front-end javascript (load dll in clientside javascript)

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南笙
南笙 2020-12-05 22:25

I have a simple clientside javascript application. I want it to load a DLL file (for a SwipeReader CR100) and call functions from the DLL library from within the javascript

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  • 被撕碎了的回忆
    被撕碎了的回忆 (楼主)
    2020-12-05 23:02

    I've done it. The solution is to use EdgeJS as a bridge between NodeJS V8 and C# CLR. Edge loads the DLL and creates a communication channel between V8 and CLR, the messages are functions of the form Func> or function(payload, callback) that are marshalled between each language VM.

    I'll post the code sample below:
    C# 

    public abstract class NetWebSocket
{
    private Func>  SendImpl { get; set; }

    protected NetWebSocket(Func> sendImpl)
    {
        this.SendImpl = sendImpl;
    }

    protected abstract Task ReceiveAsync(string message);

    public Func> ReceiveImpl
    {
        get
        {
            return async (input) =>
            {
                Console.Out.WriteLine(input);
                await this.ReceiveAsync((string) input);
                return Task.FromResult(null);
            };
        }
    }

    protected async Task SendAsync(string message)
    {
        await this.SendImpl(message);
        return;
    }
}

public class MyNetWebSocketImpl : NetWebSocket
{
    public CHello module;
    private string JSONCodelineDataRepr = "not set";

    public MyNetWebSocketImpl(Func> sendImpl) : base(sendImpl)
    {
        // do other stuff after calling the super class constructor  
        module = new CHello();
        module.DocumentReadEvent += this.DocumentReadEventHandler;
        module.DocumentReadErrorEvent += this.DocumentReadErrorEventHandler;
        // uncomment after the websocket communication works
        module.Start();
    }

    protected override async Task ReceiveAsync(string message)
    {
        // not really needed because only the NodeJS Server listens to C# .NET Server messages
        Console.WriteLine(message);
        if (message.Equals("shutdown"))
        {
            module.Close();
        }
        // not necessary (can comment the send function call)
        // if I eventually receive a message, respond with the JSON representation of the Patient ID Card
        await this.SendAsync("I received a message from you, but I'll ignore it and send you the Patient" +
                             " ID Card Data instead.. I'm a fish, so start phishing! PersonData = " +
                             JSONCodelineDataRepr);
        return;
    }

    private async void DocumentReadEventHandler(string args)
    {
        this.JSONCodelineDataRepr = args;
        await this.SendAsync(args);
    }

    private async void DocumentReadErrorEventHandler(string args)
    {
        await this.SendAsync(args);
    }
}

public class Startup
{
    
    public static MyNetWebSocketImpl ws;

    public async Task Invoke(Func> sendImpl)
    {
        ws = new MyNetWebSocketImpl(sendImpl);
       
        return ws.ReceiveImpl;
    }
}


     Javascript/NodeJS 
    

    (function(e,d,g,e){

var edge = require('edge'),
    http = require('http'),
    WebSocketServer = require('ws').Server,
    swipe = edge.func('./dlls/ActiveXCOM.dll');

var server = http.createServer(function(req,res){
    res.writeHead(200, {'Content-Type' : 'text/html'});
    res.end((
        function () { /*
            
            
            
            
            
                
    
                
    
                
            
            
        */}).toString().match(/[^]*\/\*([^]*)\*\/\}$/)[1]);
});

var wss = new WebSocketServer({server: server});

wss.on('connection', function(ws) {
    var sendImpl = function (message, callback) {
        console.log(message);
        ws.send(message);
        callback();
    };

    var receiveHandler = swipe(sendImpl, true); 

    ws.on('message', function (message) {
        receiveHandler(message);
    });

    ws.on('close', function close(){
        console.log('****************************The client disconnected!');
        receiveHandler('shutdown');
        delete receiveHandler;
    });
});

server.listen(process.env.PORT || 8080);
module.exports = this;
})();

    

    I hope the implementation is clear. If you have any trouble understanding it, please don't hesitate to write to me.
    

    Happy Coding!
    

    [Don't listen to the naysayers!]
    
    
    
             
    
                                                        
    
            
            
    
              
                
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