HttpWebRequest/HttpWebResponse 向服务器发起两次调用

Question

下面是我用来将数据发布到基于 REST 的服务器的代码片段。如果我开始在服务器上调试，我会看到两个单独的请求通过。我想知道的是为什么？

由于第二次通话，我的请求失败了。如果我调试，它显示第一个请求进展顺利，但是当我尝试读取客户端的响应时，它会向服务器发送新的调用，并且该请求无法通过身份验证。

下面内联的评论是对服务器的 2 个调用触发的地方......

        string requestUri = "/Service/Contacts";

        HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create(SERVICEBASEURI + requestUri);
        httpWebRequest.Headers.Add(AUTHENTICATE, m_AuthenticationKey);
        httpWebRequest.Headers.Add(UTCTIMESTAMP, m_UtcTime.ToString("yyyy'-'MM'-'dd HH':'mm':'ss'Z'"));
        httpWebRequest.Headers.Add(NONCE, m_NonceValue);
        httpWebRequest.Accept = "*/*";
        httpWebRequest.UserAgent = "Test-Framework";

        httpWebRequest.Method = "POST";

        string postData = "instance={\"FullName\":\"Altonymous\"}";
        byte[] postDataBytes = new ASCIIEncoding().GetBytes(postData);

        // TODO: Add postData to the Payload.  Needs to be done on authorization side as well.
        string requestPayload = GetPayload(requestUri);
        httpWebRequest.Headers.Add(AUTHORIZATION, requestPayload);
        httpWebRequest.ContentType = "application/x-www-form-urlencoded";
        httpWebRequest.ContentLength = postDataBytes.Length;

        Stream stream = httpWebRequest.GetRequestStream();
        // First call fires off to the server.  I didn't expect it to happen here...
        stream.Write(postDataBytes, 0, postDataBytes.Length);
        stream.Close();

        // Second call fires off to the server.  This is where I expected it to happen.
        using (HttpWebResponse httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse())
        {
            Assert.AreEqual(HttpStatusCode.OK, httpWebResponse.StatusCode);

            Stream responseStream = httpWebResponse.GetResponseStream();
            StreamReader responseStreamReader = new StreamReader(responseStream);
            string resultString = responseStreamReader.ReadToEnd();
            Assert.IsNotNullOrEmpty(resultString);
        }

Answer 1

试试这个~

httpWebRequest.ServicePoint.ConnectionLimit = 10;

Answer 2

看来这是微软测试设计中的一个错误。