send httprequest in order to receive some data

Question

I have some difficulties in requesting an access token from an other server.

A request to get that is:

  POST /auth/O2/token HTTP/1.1
  Host: api.amazon.com
  Content-Type: application/x-www-form-urlencoded;charset=UTF-8

  grant_type=client_credentials&scope=messaging:push&client_id=(YOUR_CLIENT_ID)&client_secret=(YOUR_CLIENT_SECRET)

and the response I want to obtain is like:

X-Amzn-RequestId: d917ceac-2245-11e2-a270-0bc161cb589d
Content-Type: application/json

{
  "access_token":"Atc|MQEWYJxEnP3I1ND03ZzbY_NxQkA7Kn7Aioev_OfMRcyVQ4NxGzJMEaKJ8f0lSOiV-yW270o6fnkI",
  "expires_in":3600,
  "scope":"messaging:push",
  "token_type":"Bearer"
 }

I tried to get it through :

private String getAccessToken(String client_id,String client_secret)
    {

            HttpWebRequest httpWReq =
            (HttpWebRequest)WebRequest.Create("http://api.amazon.com/auth/02/token");

            Encoding encoding = new UTF8Encoding();
            string postData = "grant_type=client_credentials";
            postData += "&scope=messaging:push";
            postData += "&client_id=" + client_id;
            postData += "&client_secret=" + client_secret;
            byte[] data = encoding.GetBytes(postData);

            httpWReq.Method = "POST";
            httpWReq.ContentType = "application/x-www-form-urlencoded;charset=UTF-8";
            httpWReq.ContentLength = data.Length;

            using (Stream stream = httpWReq.GetRequestStream())  // ***here I get this exception : Unable to connect to the remote server !!!****
            {
                stream.Write(data, 0, data.Length);
            }

            HttpWebResponse response = (HttpWebResponse)httpWReq.GetResponse();
            StreamReader reader = new StreamReader(response.GetResponseStream());
            String jsonresponse = "";
            String temp = null;
            while ((temp = reader.ReadLine()) != null)
            {
                jsonresponse += temp;
            }

            var dict = new JavaScriptSerializer().Deserialize<Dictionary<string, string>>(jsonresponse);
            access_token = dict["access_token"];
            String expires_in = dict["expires_in"];

        }

        return access_token;
    }

I am getting this execption : Unable to connect to the remote server, when I tried to get request stream

Answer 1

Check this ...

its not 02 its O2

in your code , it may be the error

HttpWebRequest httpWReq =
            (HttpWebRequest)WebRequest.Create("http://api.amazon.com/auth/**02**/token");

Try this

              HttpWebRequest httpWReq =
    (HttpWebRequest)WebRequest.Create("https://api.amazon.com/auth/o2/token");

Thank you ...

Answer 2

The first problem is that api.amazon.com/auth/02/token has nothing listening on port 80 (so it won't work); so probably it needs https (but if you provide reference to where this is documented we can better advise)

Secondly I think it'd be cleaner to replace the first part of your code with the following;

 using (WebClient client = new WebClient())
   {
       byte[] response = client.UploadValues("https://api.amazon.com/auth/02/token", new NameValueCollection()
       {
           { "scope", "messaging:push" },
           { "client_id", "1123" },
           { "client_secret", "2233"}
       });
       // handle response... 
   }