Facebook.FacebookApi.BeginRequest C# (CSharp) Method

        internal IAsyncResult BeginRequest(
            string url,
            HttpVerb httpVerb,
            Dictionary<string, string> args,
            AsyncCallback cb, object state)
        {
            if (args != null && args.Keys.Count > 0 && httpVerb == HttpVerb.Get)
                url = url+ (url.Contains("?") ? "&" : "?") + EncodeDictionary(args);

            var request = (HttpWebRequest)WebRequest.Create(url);
            request.Proxy = Proxy;
            request.Headers.Add(HttpRequestHeader.AcceptLanguage, Culture.IetfLanguageTag.ToLowerInvariant());
            request.Method = httpVerb.ToString();
            var tar = new TypedAsyncResult<ResponseData>(cb, state);

            Action beginGetResp = () => request.BeginGetResponse(tar.AsSafe(gr =>
            {
                HttpWebResponse resp;
                Stream respStm;
                string contentType;
                try
                {
                    resp = (HttpWebResponse)request.EndGetResponse(gr);
                    contentType = ExtractContentType(resp);
                    respStm = resp.GetResponseStream();
                }
                catch (WebException ex)
                {
                    if (ex.Status == WebExceptionStatus.ProtocolError)
                    {
                        resp = (HttpWebResponse)ex.Response;
                        contentType = ExtractContentType(resp);

                        if (contentType == "text/javascript")
                        {
                            respStm = resp.GetResponseStream();
                            goto ok;
                        }
                    }

                    throw TransportError(ex);
                }

                ok: var buf = new byte[4096];
                var ms = new MemoryStream(buf.Length);

                AsyncCallback cbr = null;
                cbr = tar.AsSafe(br =>
                {
                    int cnt = respStm.EndRead(br);
                    if (cnt == 0)
                    {
                        if (!tar.IsCompleted)
                        {
                            ((IDisposable)resp).Dispose();
                            ms.Seek(0, SeekOrigin.Begin);
                            tar.Complete(new ResponseData
                            {
                                Json = Encoding.UTF8.GetString(ms.ToArray()),
                                ContentType = contentType,
                            }, false);
                        }
                    }
                    else
                    {
                        ms.Write(buf, 0, cnt);
                        respStm.BeginRead(buf, 0, buf.Length, cbr, null);
                    }
                }, ex => ((IDisposable)resp).Dispose());

                respStm.BeginRead(buf, 0, buf.Length, cbr, null);
            }), null);

            try
            {
                if (httpVerb == HttpVerb.Post)
                {
                    string postData = EncodeDictionary(args);
                    byte[] postDataBytes = Encoding.UTF8.GetBytes(postData);
                    request.ContentType = "application/x-www-form-urlencoded";
                    request.ContentLength = postDataBytes.Length;

                    request.BeginGetRequestStream(tar.AsSafe(rar =>
                    {
                        Stream rqStm = request.EndGetRequestStream(rar);
                        rqStm.BeginWrite(postDataBytes, 0, postDataBytes.Length, tar.AsSafe(wr =>
                        {
                            rqStm.EndWrite(wr);
                            beginGetResp();
                        }), null);
                    }), null);
                }
                else
                {
                    beginGetResp();
                }
            }
            catch (Exception ex)
            {
                if (!tar.IsCompleted)
                    tar.Complete(true, ex);
            }

            return tar;
        }