Hello, I'm creating a proxy server to manage the interface between the pos module and the electronic scale. I receive well the http get request on my server, but I don't understand in wich format I have to answer with the actual weight... Can somebody tell me the correct answer format for this json request?

Here is the request I receive:

/pos/weighting_start?jsonp=jQuery18302055237984620708_1361460794237&id=r360&r=%7B%22jsonrpc%22%3A%222.0%22%2C%22method%22%3A%22call%22%2C%22params%22%3A%7B%22context%22%3A%7B%7D%7D%2C%22id%22%3A%22r360%22%7D&_=1361460812032

Url = {htp://localhost:6655/pos/weighting_start?jsonp=jQuery18302055237984620708_1361460794237&id=r360&r={"jsonrpc":"2.0","method":"call","params":{"context":{}},"id":"r360"}&_=1361460812032}

For the javascript code, it's the original device.js (..\server\openerp\addons\point_of_sale\static\src\js):

//returns the weight on the scale. 
        // is called at regular interval (up to 10x/sec) between a weighting_start()
        // and a weighting_end()
        weighting_read_kg: function(){
            var self = this;
            if(this.bypass_proxy){
                return this.weight;
            }else{
                this.message('weighting_read_kg',{})
                    .done(function(weight){
                        if(self.weighting && !self.bypass_proxy){
                            self.weight = weight;
                        }
                    });
                return this.weight;
            }
        },

I'm making the server in C#.

I have every data I need but don't know how to format them... Here is the reponse code:

private void HttpWebServer_SendData()
        {
            if (context == null) return;

            string responseString = RxString;
            byte[] buffer = Encoding.UTF8.GetBytes(responseString);
            context.Response.ContentLength64 = buffer.Length;

            context.Response.Headers.Set(HttpResponseHeader.Server, "Serial to http Server");

            System.IO.Stream output = context.Response.OutputStream;
            output.Write(buffer, 0, buffer.Length);
            output.Close();
        }

where RxString is the actual weight, ex: "120.5"

Thank you