Question

I have this code

using (var stream = new StreamWriter(request.GetRequestStream(), Encoding))
   stream.Write(body.ToString());

I need to make it asynchronous. As far as I understand it, this means I need to change the call to request.GetRequestStream() to the asychronous.BeginGetRequestStream(). I have seen this example but cannot figure out how to apply that to this scenario. Can someone help?

Answer 1

The documentation has a good example (http://msdn.microsoft.com/en-us/library/system.net.httpwebrequest.begingetrequeststream(v=vs.100).aspx):

using System;
using System.Net;
using System.IO;
using System.Text;
using System.Threading;

class HttpWebRequestBeginGetRequest
{
    private static ManualResetEvent allDone = new ManualResetEvent(false);
public static void Main(string[] args)
{
    // Create a new HttpWebRequest object.
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://www.contoso.com/example.aspx");

    request.ContentType = "application/x-www-form-urlencoded";

    // Set the Method property to 'POST' to post data to the URI.
    request.Method = "POST";

    // start the asynchronous operation
    request.BeginGetRequestStream(new AsyncCallback(GetRequestStreamCallback), request);

    // Keep the main thread from continuing while the asynchronous 
    // operation completes. A real world application 
    // could do something useful such as updating its user interface. 
    allDone.WaitOne();
}

private static void GetRequestStreamCallback(IAsyncResult asynchronousResult)
{
    HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;

    // End the operation
    Stream postStream = request.EndGetRequestStream(asynchronousResult);

    Console.WriteLine("Please enter the input data to be posted:");
    string postData = Console.ReadLine();

    // Convert the string into a byte array. 
    byte[] byteArray = Encoding.UTF8.GetBytes(postData);

    // Write to the request stream.
    postStream.Write(byteArray, 0, postData.Length);
    postStream.Close();

    // Start the asynchronous operation to get the response
    request.BeginGetResponse(new AsyncCallback(GetResponseCallback), request);
}

private static void GetResponseCallback(IAsyncResult asynchronousResult)
{
    HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;

    // End the operation
    HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(asynchronousResult);
    Stream streamResponse = response.GetResponseStream();
    StreamReader streamRead = new StreamReader(streamResponse);
    string responseString = streamRead.ReadToEnd();
    Console.WriteLine(responseString);
    // Close the stream object
    streamResponse.Close();
    streamRead.Close();

    // Release the HttpWebResponse
    response.Close();
    allDone.Set();
}