Async HttpWebRequest

[APA]

I've seen the MS sample async web request pattern and I ask is it really async if it is using a ManualResetEven t and setting WaitOne()? The
ManualResetEven t object is being declared as a static variable so isn't it causing problems with other threads that may be using the same class to
execute the async web request? If I remove the ManualResetEven t object will it be truly asynchronous and will I be losing something? Also, in my app
the web request is posting data.

For those that haven't seen the code it looks something like this:
public class AsyncWebRequest

public AsyncWebRequest (){}

public static ManualResetEven t allDone = new ManualResetEven t(false);

const int BUFFER_SIZE = 1024;

public void WebReq(string URL, string somedata)
{
try
{

if (URL.Trim() != "")
{
byte[] data = Encoding.ASCII. GetBytes(someda ta);

HttpWebRequest webRequest = (HttpWebRequest )System.Net.Web Request.Create( URL);
webRequest.Meth od = "POST";
webRequest.Cont entType = "applicatio n/x-www-form-urlencoded";
webRequest.Cont entLength = data.Length;

ManualResetEven t WaitHndle = new ManualResetEven t(false);
RequestState rs = new RequestState(Wa itHndle,this.De bug);

rs.Request = webRequest;
rs.DataToSend = data;

webRequest.Begi nGetRequestStre am(new AsyncCallback(R eadCallbackRequ est), rs);

IAsyncResult r = (IAsyncResult)w ebRequest.Begin GetResponse(new AsyncCallback(R espCallback), rs);

ThreadPool.Regi sterWaitForSing leObject(r.Asyn cWaitHandle, new WaitOrTimerCall back(ScanTimeou tCallback), rs, (30 * 1000), true);

allDone.WaitOne ();
rs.ResponseStre am.Close();

}
}
catch (WebException ex) { string str = ex.ToString(); }
catch (Exception ex) { string sr = ex.ToString(); }
}
private static void RespCallback(IA syncResult ar)
{
RequestState rs = (RequestState)a r.AsyncState;
try
{
WebRequest req = rs.Request;

WebResponse resp = req.EndGetRespo nse(ar);

Stream ResponseStream = resp.GetRespons eStream();

rs.ResponseStre am = ResponseStream;
rs.Waitone.Set( );

if (rs.Debug)
{
IAsyncResult iarRead = ResponseStream. BeginRead(rs.Bu fferRead, 0, BUFFER_SIZE, new AsyncCallback(R eadCallBack), rs);
}
}
catch (Exception ex)
{
rs.Waitone.Set( );
}
}
private static void ReadCallbackReq uest(IAsyncResu lt asynchronousRes ult)
{
RequestState rs = (RequestState)a synchronousResu lt.AsyncState;
try
{
HttpWebRequest request = rs.Request;

Stream postStream = request.EndGetR equestStream(as ynchronousResul t);

postStream.Writ e(rs.DataToSend , 0, rs.DataToSend.L ength);
postStream.Clos e();
}
catch (Exception ex)
{
}
allDone.Set();

}

private static void ScanTimeoutCall back(object state, bool timedOut)
{
if (timedOut)
{
RequestState reqState = (RequestState)s tate;
if (reqState != null)
reqState.Reques t.Abort();
}
}

public class RequestState
{
const int BufferSize = 1024;
public byte[] DataToSend;
public StringBuilder RequestData;
public byte[] BufferRead;
public HttpWebRequest Request;
public Stream ResponseStream;
public ManualResetEven t Waitone;
public bool Debug;

public Decoder StreamDecode = Encoding.UTF8.G etDecoder();

public RequestState(Ma nualResetEvent waitHandle,bool debug)
{
BufferRead = new byte[BufferSize];
RequestData = new StringBuilder(S tring.Empty);
Request = null;
ResponseStream = null;
Waitone = waitHandle;
Debug = debug;
}
}
}

[=?Utf-8?B?YnJ1Y2UgYmFya2Vy?=]

normally you would put code you want to happen during the async request
before the wait. then after the wait, you put the code to handle the response.

the question is what do you want the thread to do during the request call?
after?

note: this code will not work from an asp.net application. if a webform, use
the builting async processing, if called from a web service, you will want to
use a WaitHandle rather than ManualResetEven t.

-- bruce (sqlwork.com)
"APA" wrote:

I've seen the MS sample async web request pattern and I ask is it really async if it is using a ManualResetEven t and setting WaitOne()? The
ManualResetEven t object is being declared as a static variable so isn't it causing problems with other threads that may be using the same class to
execute the async web request? If I remove the ManualResetEven t object will it be truly asynchronous and will I be losing something? Also, in my app
the web request is posting data.

For those that haven't seen the code it looks something like this:
public class AsyncWebRequest

public AsyncWebRequest (){}

public static ManualResetEven t allDone = new ManualResetEven t(false);

const int BUFFER_SIZE = 1024;

public void WebReq(string URL, string somedata)
{
try
{

if (URL.Trim() != "")
{
byte[] data = Encoding.ASCII. GetBytes(someda ta);

HttpWebRequest webRequest = (HttpWebRequest )System.Net.Web Request.Create( URL);
webRequest.Meth od = "POST";
webRequest.Cont entType = "applicatio n/x-www-form-urlencoded";
webRequest.Cont entLength = data.Length;

ManualResetEven t WaitHndle = new ManualResetEven t(false);
RequestState rs = new RequestState(Wa itHndle,this.De bug);

rs.Request = webRequest;
rs.DataToSend = data;

webRequest.Begi nGetRequestStre am(new AsyncCallback(R eadCallbackRequ est), rs);

IAsyncResult r = (IAsyncResult)w ebRequest.Begin GetResponse(new AsyncCallback(R espCallback), rs);

ThreadPool.Regi sterWaitForSing leObject(r.Asyn cWaitHandle, new WaitOrTimerCall back(ScanTimeou tCallback), rs, (30 * 1000), true);

allDone.WaitOne ();
rs.ResponseStre am.Close();

}
}
catch (WebException ex) { string str = ex.ToString(); }
catch (Exception ex) { string sr = ex.ToString(); }
}
private static void RespCallback(IA syncResult ar)
{
RequestState rs = (RequestState)a r.AsyncState;
try
{
WebRequest req = rs.Request;

WebResponse resp = req.EndGetRespo nse(ar);

Stream ResponseStream = resp.GetRespons eStream();

rs.ResponseStre am = ResponseStream;
rs.Waitone.Set( );

if (rs.Debug)
{
IAsyncResult iarRead = ResponseStream. BeginRead(rs.Bu fferRead, 0, BUFFER_SIZE, new AsyncCallback(R eadCallBack), rs);
}
}
catch (Exception ex)
{
rs.Waitone.Set( );
}
}
private static void ReadCallbackReq uest(IAsyncResu lt asynchronousRes ult)
{
RequestState rs = (RequestState)a synchronousResu lt.AsyncState;
try
{
HttpWebRequest request = rs.Request;

Stream postStream = request.EndGetR equestStream(as ynchronousResul t);

postStream.Writ e(rs.DataToSend , 0, rs.DataToSend.L ength);
postStream.Clos e();
}
catch (Exception ex)
{
}
allDone.Set();

}

private static void ScanTimeoutCall back(object state, bool timedOut)
{
if (timedOut)
{
RequestState reqState = (RequestState)s tate;
if (reqState != null)
reqState.Reques t.Abort();
}
}

public class RequestState
{
const int BufferSize = 1024;
public byte[] DataToSend;
public StringBuilder RequestData;
public byte[] BufferRead;
public HttpWebRequest Request;
public Stream ResponseStream;
public ManualResetEven t Waitone;
public bool Debug;

public Decoder StreamDecode = Encoding.UTF8.G etDecoder();

public RequestState(Ma nualResetEvent waitHandle,bool debug)
{
BufferRead = new byte[BufferSize];
RequestData = new StringBuilder(S tring.Empty);
Request = null;
ResponseStream = null;
Waitone = waitHandle;
Debug = debug;
}
}
}