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  1. PO
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    <p>Hope, this example will help you.</p> <pre><code>public class MessagingServices { public static IAsyncResult BeginReverseEcho (TcpClient client, AsyncCallback callback, object userState) { var re = new ReverseEcho( ); re.Begin (client, callback, userState); return re; } public static byte[] EndReverseEcho (IAsyncResult r) { return ((ReverseEcho)r).End( ); } } class ReverseEcho : IAsyncResult { volatile TcpClient _client; volatile NetworkStream _stream; volatile object _userState; volatile AsyncCallback _callback; ManualResetEvent _waitHandle = new ManualResetEvent (false); volatile int _bytesRead = 0; byte[] _data = new byte [5000]; volatile Exception _exception; internal ReverseEcho( ) { } // IAsyncResult members: public object AsyncState { get { return _userState; } } public WaitHandle AsyncWaitHandle { get { return _waitHandle; } } public bool CompletedSynchronously { get { return false; } } public bool IsCompleted { get { return _waitHandle.WaitOne (0, false); } } internal void Begin (TcpClient c, AsyncCallback callback, object state) { _client = c; _callback = callback; _userState = state; try { _stream = _client.GetStream( ); Read( ); } catch (Exception ex) { ProcessException (ex); } } internal byte[] End( ) // Wait for completion + rethrow any error. { AsyncWaitHandle.WaitOne( ); AsyncWaitHandle.Close( ); if (_exception != null) throw _exception; return _data; } void Read( ) // This is always called from an exception-handled method { _stream.BeginRead (_data, _bytesRead, _data.Length - _bytesRead, ReadCallback, null); } void ReadCallback (IAsyncResult r) { try { int chunkSize = _stream.EndRead (r); _bytesRead += chunkSize; if (chunkSize &gt; 0 &amp;&amp; _bytesRead &lt; _data.Length) { Read( ); // More data to read! return; } Array.Reverse (_data); _stream.BeginWrite (_data, 0, _data.Length, WriteCallback, null); } catch (Exception ex) { ProcessException (ex); } } void WriteCallback (IAsyncResult r) { try { _stream.EndWrite (r); } catch (Exception ex) { ProcessException (ex); return; } Cleanup( ); } void ProcessException (Exception ex) { _exception = ex; // This exception will get rethrown when Cleanup(); // the consumer calls the End( ) method. } void Cleanup( ) { try { if (_stream != null) _stream.Close( ); } catch (Exception ex) { if (_exception != null) _exception = ex; } // Signal that we're done and fire the callback. _waitHandle.Set( ); if (_callback != null) _callback (this); } } </code></pre> <p>Example is taken from C# 3.0 in a Nutshell, 3rd Edition by Joseph Albahari; Ben Albahari </p>
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    1. POHow do I create a class with asynchronous capabilities (similiar to SqlCommand or WebRequest)?
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    1. USValentin
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      1. VTUpMod
    1. COThanks, that's kind of blowing my mind at the moment but I will continue to study it.
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      1. USJames
    2. CO@Valentin Vasiliev: Unfortunately, it's not the pattern he is looking for. He is looking for the event-based async pattern.
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      1. UScasperOne
    3. COEvent-based async patterns are generally simpler, so I hope he'll handle the easier one :-)
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