.NET服務響應500內部錯誤和「缺少參數」到HttpWebRequest POSTS，但測試表單工作正常

Question

我使用簡單的.NET服務（asmx），通過測試表單（POST）調用時工作正常。當通過HttpWebRequest對象調用時，我得到一個WebException「System.Net.WebException：遠程服務器返回錯誤：（500）內部服務器錯誤。」深入挖掘，閱讀WebException.Response.GetResponseStream（）我得到消息：「Missing parameter：serviceType。」但我清楚地包含了這個參數。

我在這裏很茫然，更糟糕的是我沒有權限調試服務本身。

這裏正在使用的代碼，以使該請求：

string postData = String.Format("serviceType={0}&SaleID={1}&Zip={2}", request.service, request.saleId, request.postalCode); 
byte[] data = (new ASCIIEncoding()).GetBytes(postData); 

HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create(url); 
httpWebRequest.Timeout = 60000; 
httpWebRequest.Method = "POST"; 
httpWebRequest.ContentType = "application/x-www-form-urlencoded"; 
httpWebRequest.ContentLength = data.Length; 

using (Stream newStream = httpWebRequest.GetRequestStream()) 
{ 
    newStream.Write(data, 0, data.Length); 
} 

try 
{ 
    using (response = (HttpWebResponse)httpWebRequest.GetResponse()) 
    { 
     if (response.StatusCode != HttpStatusCode.OK) 
      throw new Exception("There was an error with the shipping freight service."); 

     string responseData; 
     using (StreamReader responseStream = new  StreamReader(httpWebRequest.GetResponse().GetResponseStream(), System.Text.Encoding.GetEncoding("iso-8859-1"))) 
     { 
      responseData = responseStream.ReadToEnd(); 
      responseStream.Close(); 
     } 

     if (string.IsNullOrEmpty(responseData)) 
      throw new Exception("There was an error with the shipping freight service. Request went through but response is empty."); 

     XmlDocument providerResponse = new XmlDocument(); 
     providerResponse.LoadXml(responseData); 

     return providerResponse; 
    } 
} 
catch (WebException webExp) 
{ 
    string exMessage = webExp.Message; 

    if (webExp.Response != null) 
    { 
     using (StreamReader responseReader = new StreamReader(webExp.Response.GetResponseStream())) 
     { 
      exMessage = responseReader.ReadToEnd(); 
     } 
    } 

    throw new Exception(exMessage); 
} 

任何人都有一個想法可能是這樣嗎？

謝謝。

UPDATE

通過調試器，我看到參數是正確的。我也看到在提琴手中的參數是正確的。

檢查fiddler，每次執行代碼時都會收到2個請求。第一個請求是發送參數的帖子。它會得到一個301響應代碼，其中包含一個「Document Moved Object Moved此文檔可能在此處」的消息。第二個請求是對沒有正文的同一個URL的GET。 「缺少參數：serviceType」會導致500服務器錯誤。信息。

Answer 1

看起來你發現你的問題，當你看着小提琴手的請求。以摘錄自http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html：

10.3.2 301 Moved Permanently

The requested resource has been assigned a new permanent URI and any future references to this resource SHOULD use one of the returned URIs. Clients with link editing capabilities ought to automatically re-link references to the Request-URI to one or more of the new references returned by the server, where possible.

.....

Note: When automatically redirecting a POST request after receiving a 301 status code, some existing HTTP/1.0 user agents will erroneously change it into a GET request.

這裏，你可以採取幾個選項：

1. 硬編碼程序中使用，你在提琴手
2. 301響應看到新網址調整您的代碼以檢索301響應，從響應中解析出新的Url，然後使用新的Url構建新的響應。

如果您正在處理Url上的基於用戶的輸入（如網絡瀏覽器），後一個選項將是理想的，因爲您不知道用戶要在哪裏使用程序。