WebRequest.GetRequestStreamAsync() method timesout each time for MNS access token

问题

I am trying to get the access token from MNS for Push notifications and the WebRequest.GetRequestStreamAsync() method timesout each time. Any suggestions?

Reference: http://msdn.microsoft.com/en-us/library/windows/apps/hh913756.aspx

Below is the code I use

        HttpWebRequest webRequest = (HttpWebRequest)HttpWebRequest.Create("https://login.live.com/accesstoken.srf");
        webRequest.Method = "POST";
        webRequest.ContentType = "application/x-www-form-urlencoded";

        string postString = String.Format("grant_type=client_credentials&client_id={0}&client_secret={1}&scope=notify.windows.com",
                              SID,
                              SECRET_KEY);
        byte[] data = Encoding.UTF8.GetBytes(postString);
        Stream newStream = await webRequest.GetRequestStreamAsync();
        newStream.Write(data, 0, data.Length);

回答1:

Try rewriting it like this and see if it makes a difference. I've sometimes had problems with HttpWebRequest where WebRequest worked fine. Also make sure you close your streams.

    WebRequest webRequest = WebRequest.Create("https://login.live.com/accesstoken.srf");
    webRequest.Method = "POST";
    webRequest.ContentType = "application/x-www-form-urlencoded";

    string postString = String.Format("grant_type=client_credentials&client_id={0}&client_secret={1}&scope=notify.windows.com",
                          SID,
                          SECRET_KEY);
    byte[] data = Encoding.UTF8.GetBytes(postString);
    Stream newStream = await webRequest.GetRequestStreamAsync();
    newStream.Write(data, 0, data.Length);
    newStream.Close();

    WebResponse response = webRequest.GetResponse();
    StreamReader requestReader = new StreamReader( response.GetResponseStream() );
    string webResponse = requestReader.ReadToEnd();
    response.Close();

回答2:

Call .ConfigureAwait(false) on your Async method.

This blog post should explain the why and how.

回答3:

We had the same problem and it turned out to be a problem in different place than one would originally guess.

You need to .Dispose() or at least .Close() the response that you get from .GetResponseAsync, otherwise the next call to .GetRequestStreamAsync hangs.

It seems that the code behind this holds some limited (rather low) amount of sockets or locks, that disallow further requests to even begin until previous request has completed.

来源：https://stackoverflow.com/questions/17032338/webrequest-getrequeststreamasync-method-timesout-each-time-for-mns-access-toke