Async HttpWebRequest catch WebException

Question

I am trying to catch WebException from asynchronous HttpWebRequest to read soap:fault from api. But it throws AggregateException. Is there a way to catch WebException for Async HttpWebRequest ?

public async Task<XDocument> GetXmlSoapResponseAsync(string soapRequestURL, string xmlData)
    {
      try
      {
        //create xml doc
        XmlDocument doc = new XmlDocument();

        //load xml document frtom xmlData
        doc.LoadXml(xmlData);
        //creta web request
        HttpWebRequest req = (HttpWebRequest)WebRequest.Create(soapRequestURL);
        req.ContentType = "text/xml";
        req.Accept = "text/xml";
        req.Method = "POST";

        //GetRequestStream from req
        Stream stm = req.GetRequestStream();
        doc.Save(stm);
        stm.Close();

        Task<WebResponse> task = Task.Factory.FromAsync(
        req.BeginGetResponse,
        asyncResult => req.EndGetResponse(asyncResult),
        (object)null);

        var response = task.Result;
        return await task.ContinueWith(t => ReadStreamFromResponse(response,stm, soapRequestURL,xmlData));
      }
      catch (WebException webException)
      {
        LogWebException(webException, soapRequestURL, xmlData);

        return null;
      }

    }

Answer 1

Change this

var response = task.Result;

to this

var response = await task;

await returns the result of the task or unwraps the AggregateException, if any.

---

Also, .Result blocks the current thread until the result is available, and that's probably not what you want, otherwise you'd just be using the blocking GetResponse, instead of the async BeginGetResponse and EndGetResponse.

Also, you don't even need those two methods. There's a better one - GetResponseAsync

Use this:

var response = await req.GetResponseAsync();

Instead of this:

Task<WebResponse> task = Task.Factory.FromAsync(
req.BeginGetResponse,
asyncResult => req.EndGetResponse(asyncResult),
(object)null);

var response = task.Result;