* Cleaned namespaces of entire solution. OpenSim directories now correspond with namespaces.

author: Adam Frisby 2008-05-01 15:36:39 +0000
committer: Adam Frisby 2008-05-01 15:36:39 +0000
commit: a1c8aa4050b7f7a94e02dd40d8cd456f258b4e2b (patch)
tree: a71b99297fa2b57f7c53492fe18f48b3d3ad8827 /OpenSim/Framework/Communications/RestClient.cs
parent: Moving LaunchSLClient source files so build works (2/2) (diff)
download: opensim-SC-a1c8aa4050b7f7a94e02dd40d8cd456f258b4e2b.zip
opensim-SC-a1c8aa4050b7f7a94e02dd40d8cd456f258b4e2b.tar.gz
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1 files changed, 368 insertions, 0 deletions
diff --git a/OpenSim/Framework/Communications/RestClient.cs b/OpenSim/Framework/Communications/RestClient.cs
new file mode 100644
index 0000000..91284e8
--- /dev/null
+++ b/OpenSim/Framework/Communications/RestClient.cs
@@ -0,0 +1,368 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Net;
+using System.Reflection;
+using System.Text;
+using System.Threading;
+using System.Web;
+using log4net;
+namespace OpenSim.Framework.Communications
+{
+    /// <summary>
+    /// Implementation of a generic REST client
+    /// </summary>
+    /// <remarks>
+    /// This class is a generic implementation of a REST (Representational State Transfer) web service. This
+    /// class is designed to execute both synchroneously and asynchroneously.
+    /// 
+    /// Internally the implementation works as a two stage asynchroneous web-client.
+    /// When the request is initiated, RestClient will query asynchroneously for for a web-response,
+    /// sleeping until the initial response is returned by the server. Once the initial response is retrieved
+    /// the second stage of asynchroneous requests will be triggered, in an attempt to read of the response
+    /// object into a memorystream as a sequence of asynchroneous reads.
+    /// 
+    /// The asynchronisity of RestClient is designed to move as much processing into the back-ground, allowing 
+    /// other threads to execute, while it waits for a response from the web-service. RestClient it self, can be
+    /// invoked by the caller in either synchroneous mode or asynchroneous mode.
+    /// </remarks>
+    public class RestClient
+    {
+        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
+        private string realuri;
+        #region member variables
+        /// <summary>
+        /// The base Uri of the web-service e.g. http://www.google.com 
+        /// </summary>
+        private string _url;
+        /// <summary>
+        /// Path elements of the query
+        /// </summary>
+        private List<string> _pathElements = new List<string>();
+        /// <summary>
+        /// Parameter elements of the query, e.g. min=34
+        /// </summary>
+        private Dictionary<string, string> _parameterElements = new Dictionary<string, string>();
+        /// <summary>
+        /// Request method. E.g. GET, POST, PUT or DELETE
+        /// </summary>
+        private string _method;
+        /// <summary>
+        /// Temporary buffer used to store bytes temporarily as they come in from the server
+        /// </summary>
+        private byte[] _readbuf;
+        /// <summary>
+        /// MemoryStream representing the resultiong resource
+        /// </summary>
+        private Stream _resource;
+        /// <summary>
+        /// WebRequest object, held as a member variable
+        /// </summary>
+        private HttpWebRequest _request;
+        /// <summary>
+        /// WebResponse object, held as a member variable, so we can close it
+        /// </summary>
+        private HttpWebResponse _response;
+        /// <summary>
+        /// This flag will help block the main synchroneous method, in case we run in synchroneous mode
+        /// </summary>
+        public static ManualResetEvent _allDone = new ManualResetEvent(false);
+        /// <summary>
+        /// Default time out period
+        /// </summary>
+        private const int DefaultTimeout = 10*1000; // 10 seconds timeout
+        /// <summary>
+        /// Default Buffer size of a block requested from the web-server
+        /// </summary>
+        private const int BufferSize = 4096; // Read blocks of 4 KB.
+        /// <summary>
+        /// if an exception occours during async processing, we need to save it, so it can be 
+        /// rethrown on the primary thread;
+        /// </summary>
+        private Exception _asyncException;
+        #endregion member variables
+        #region constructors
+        /// <summary>
+        /// Instantiate a new RestClient
+        /// </summary>
+        /// <param name="url">Web-service to query, e.g. http://osgrid.org:8003</param>
+        public RestClient(string url)
+        {
+            _url = url;
+            _readbuf = new byte[BufferSize];
+            _resource = new MemoryStream();
+            _request = null;
+            _response = null;
+            _lock = new object();
+        }
+        private object _lock;
+        #endregion constructors
+        /// <summary>
+        /// Add a path element to the query, e.g. assets
+        /// </summary>
+        /// <param name="element">path entry</param>
+        public void AddResourcePath(string element)
+        {
+            if (isSlashed(element))
+                _pathElements.Add(element.Substring(0, element.Length - 1));
+            else
+                _pathElements.Add(element);
+        }
+        /// <summary>
+        /// Add a query parameter to the Url
+        /// </summary>
+        /// <param name="name">Name of the parameter, e.g. min</param>
+        /// <param name="value">Value of the parameter, e.g. 42</param>
+        public void AddQueryParameter(string name, string value)
+        {
+            _parameterElements.Add(HttpUtility.UrlEncode(name), HttpUtility.UrlEncode(value));
+        }
+        /// <summary>
+        /// Add a query parameter to the Url
+        /// </summary>
+        /// <param name="name">Name of the parameter, e.g. min</param>
+        public void AddQueryParameter(string name)
+        {
+            _parameterElements.Add(HttpUtility.UrlEncode(name), null);
+        }
+        /// <summary>
+        /// Web-Request method, e.g. GET, PUT, POST, DELETE
+        /// </summary>
+        public string RequestMethod
+        {
+            get { return _method; }
+            set { _method = value; }
+        }
+        /// <summary>
+        /// True if string contains a trailing slash '/'
+        /// </summary>
+        /// <param name="s">string to be examined</param>
+        /// <returns>true if slash is present</returns>
+        private bool isSlashed(string s)
+        {
+            return s.Substring(s.Length - 1, 1) == "/";
+        }
+        /// <summary>
+        /// Build a Uri based on the initial Url, path elements and parameters
+        /// </summary>
+        /// <returns>fully constructed Uri</returns>
+        private Uri buildUri()
+        {
+            StringBuilder sb = new StringBuilder();
+            sb.Append(_url);
+            foreach (string e in _pathElements)
+            {
+                sb.Append("/");
+                sb.Append(e);
+            }
+            bool firstElement = true;
+            foreach (KeyValuePair<string, string> kv in _parameterElements)
+            {
+                if (firstElement)
+                {
+                    sb.Append("?");
+                    firstElement = false;
+                }
+                else
+                    sb.Append("&");
+                sb.Append(kv.Key);
+                if (kv.Value != null && kv.Value.Length != 0)
+                {
+                    sb.Append("=");
+                    sb.Append(kv.Value);
+                }
+            }
+            realuri = sb.ToString();
+            //m_log.InfoFormat("[REST CLIENT]: RestURL: {0}", realuri);
+            return new Uri(sb.ToString());
+        }
+        #region Async communications with server
+        /// <summary>
+        /// Async method, invoked when a block of data has been received from the service
+        /// </summary>
+        /// <param name="ar"></param>
+        private void StreamIsReadyDelegate(IAsyncResult ar)
+        {
+            try
+            {
+                Stream s = (Stream) ar.AsyncState;
+                int read = s.EndRead(ar);
+                if (read > 0)
+                {
+                    _resource.Write(_readbuf, 0, read);
+                    IAsyncResult asynchronousResult =
+                        s.BeginRead(_readbuf, 0, BufferSize, new AsyncCallback(StreamIsReadyDelegate), s);
+                    // TODO! Implement timeout, without killing the server
+                    //ThreadPool.RegisterWaitForSingleObject(asynchronousResult.AsyncWaitHandle, new WaitOrTimerCallback(TimeoutCallback), _request, DefaultTimeout, true);
+                }
+                else
+                {
+                    s.Close();
+                    _allDone.Set();
+                }
+            }
+            catch (Exception e)
+            {
+                _allDone.Set();
+                _asyncException = e;
+            }
+        }
+        #endregion Async communications with server
+        /// <summary>
+        /// Perform synchroneous request
+        /// </summary>
+        public Stream Request()
+        {
+            lock (_lock)
+            {
+                _request = (HttpWebRequest) WebRequest.Create(buildUri());
+                _request.KeepAlive = false;
+                _request.ContentType = "application/xml";
+                _request.Timeout = 200000;
+                _asyncException = null;
+//                IAsyncResult responseAsyncResult = _request.BeginGetResponse(new AsyncCallback(ResponseIsReadyDelegate), _request);
+                _response = (HttpWebResponse) _request.GetResponse();
+                Stream src = _response.GetResponseStream();
+                int length = src.Read(_readbuf, 0, BufferSize);
+                while (length > 0)
+                {
+                    _resource.Write(_readbuf, 0, length);
+                    length = src.Read(_readbuf, 0, BufferSize);
+                }
+                // TODO! Implement timeout, without killing the server
+                // this line implements the timeout, if there is a timeout, the callback fires and the request becomes aborted
+                //ThreadPool.RegisterWaitForSingleObject(responseAsyncResult.AsyncWaitHandle, new WaitOrTimerCallback(TimeoutCallback), _request, DefaultTimeout, true);
+//                _allDone.WaitOne();
+                if (_response != null)
+                    _response.Close();
+                if (_asyncException != null)
+                    throw _asyncException;
+                if (_resource != null)
+                {
+                    _resource.Flush();
+                    _resource.Seek(0, SeekOrigin.Begin);
+                }
+                return _resource;
+            }
+        }
+        public Stream Request(Stream src)
+        {
+            _request = (HttpWebRequest) WebRequest.Create(buildUri());
+            _request.KeepAlive = false;
+            _request.ContentType = "application/xml";
+            _request.Timeout = 900000;
+            _request.Method = RequestMethod;
+            _asyncException = null;
+            _request.ContentLength = src.Length;
+            m_log.InfoFormat("[REST]: Request Length {0}", _request.ContentLength);
+            m_log.InfoFormat("[REST]: Sending Web Request {0}", buildUri());
+            src.Seek(0, SeekOrigin.Begin);
+            m_log.Info("[REST]: Seek is ok");
+            Stream dst = _request.GetRequestStream();
+            m_log.Info("[REST]: GetRequestStream is ok");
+            byte[] buf = new byte[1024];
+            int length = src.Read(buf, 0, 1024);
+            m_log.Info("[REST]: First Read is ok");
+            while (length > 0)
+            {
+                dst.Write(buf, 0, length);
+                length = src.Read(buf, 0, 1024);
+            }
+            _response = (HttpWebResponse) _request.GetResponse();
+//            IAsyncResult responseAsyncResult = _request.BeginGetResponse(new AsyncCallback(ResponseIsReadyDelegate), _request);
+            // TODO! Implement timeout, without killing the server
+            // this line implements the timeout, if there is a timeout, the callback fires and the request becomes aborted
+            //ThreadPool.RegisterWaitForSingleObject(responseAsyncResult.AsyncWaitHandle, new WaitOrTimerCallback(TimeoutCallback), _request, DefaultTimeout, true);
+            return null;
+        }
+        #region Async Invocation
+        public IAsyncResult BeginRequest(AsyncCallback callback, object state)
+        {
+            /// <summary>
+            /// In case, we are invoked asynchroneously this object will keep track of the state
+            /// </summary>
+            AsyncResult<Stream> ar = new AsyncResult<Stream>(callback, state);
+            ThreadPool.QueueUserWorkItem(RequestHelper, ar);
+            return ar;
+        }
+        public Stream EndRequest(IAsyncResult asyncResult)
+        {
+            AsyncResult<Stream> ar = (AsyncResult<Stream>) asyncResult;
+            // Wait for operation to complete, then return result or 
+            // throw exception
+            return ar.EndInvoke();
+        }
+        private void RequestHelper(Object asyncResult)
+        {
+            // We know that it's really an AsyncResult<DateTime> object
+            AsyncResult<Stream> ar = (AsyncResult<Stream>) asyncResult;
+            try
+            {
+                // Perform the operation; if sucessful set the result
+                Stream s = Request();
+                ar.SetAsCompleted(s, false);
+            }
+            catch (Exception e)
+            {
+                // If operation fails, set the exception
+                ar.HandleException(e, false);
+            }
+        }
+        #endregion Async Invocation
+    }
+}
+\ No newline at end of file
author	Adam Frisby	2008-05-01 15:36:39 +0000
committer	Adam Frisby	2008-05-01 15:36:39 +0000
commit	a1c8aa4050b7f7a94e02dd40d8cd456f258b4e2b (patch)
tree	a71b99297fa2b57f7c53492fe18f48b3d3ad8827 /OpenSim/Framework/Communications/RestClient.cs
parent	Moving LaunchSLClient source files so build works (2/2) (diff)
download	opensim-SC-a1c8aa4050b7f7a94e02dd40d8cd456f258b4e2b.zip opensim-SC-a1c8aa4050b7f7a94e02dd40d8cd456f258b4e2b.tar.gz opensim-SC-a1c8aa4050b7f7a94e02dd40d8cd456f258b4e2b.tar.bz2 opensim-SC-a1c8aa4050b7f7a94e02dd40d8cd456f258b4e2b.tar.xz

diff --git a/OpenSim/Framework/Communications/RestClient.cs b/OpenSim/Framework/Communications/RestClient.cs new file mode 100644 index 0000000..91284e8 --- /dev/null +++ b/OpenSim/Framework/Communications/RestClient.cs
@@ -0,0 +1,368 @@
	1	using System;
	2	using System.Collections.Generic;
	3	using System.IO;
	4	using System.Net;
	5	using System.Reflection;
	6	using System.Text;
	7	using System.Threading;
	8	using System.Web;
	9	using log4net;
	10
	11	namespace OpenSim.Framework.Communications
	12	{
	13	/// <summary>
	14	/// Implementation of a generic REST client
	15	/// </summary>
	16	/// <remarks>
	17	/// This class is a generic implementation of a REST (Representational State Transfer) web service. This
	18	/// class is designed to execute both synchroneously and asynchroneously.
	19	///
	20	/// Internally the implementation works as a two stage asynchroneous web-client.
	21	/// When the request is initiated, RestClient will query asynchroneously for for a web-response,
	22	/// sleeping until the initial response is returned by the server. Once the initial response is retrieved
	23	/// the second stage of asynchroneous requests will be triggered, in an attempt to read of the response
	24	/// object into a memorystream as a sequence of asynchroneous reads.
	25	///
	26	/// The asynchronisity of RestClient is designed to move as much processing into the back-ground, allowing
	27	/// other threads to execute, while it waits for a response from the web-service. RestClient it self, can be
	28	/// invoked by the caller in either synchroneous mode or asynchroneous mode.
	29	/// </remarks>
	30	public class RestClient
	31	{
	32	private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
	33
	34	private string realuri;
	35
	36	#region member variables
	37
	38	/// <summary>
	39	/// The base Uri of the web-service e.g. http://www.google.com
	40	/// </summary>
	41	private string _url;
	42
	43	/// <summary>
	44	/// Path elements of the query
	45	/// </summary>
	46	private List<string> _pathElements = new List<string>();
	47
	48	/// <summary>
	49	/// Parameter elements of the query, e.g. min=34
	50	/// </summary>
	51	private Dictionary<string, string> _parameterElements = new Dictionary<string, string>();
	52
	53	/// <summary>
	54	/// Request method. E.g. GET, POST, PUT or DELETE
	55	/// </summary>
	56	private string _method;
	57
	58	/// <summary>
	59	/// Temporary buffer used to store bytes temporarily as they come in from the server
	60	/// </summary>
	61	private byte[] _readbuf;
	62
	63	/// <summary>
	64	/// MemoryStream representing the resultiong resource
	65	/// </summary>
	66	private Stream _resource;
	67
	68	/// <summary>
	69	/// WebRequest object, held as a member variable
	70	/// </summary>
	71	private HttpWebRequest _request;
	72
	73	/// <summary>
	74	/// WebResponse object, held as a member variable, so we can close it
	75	/// </summary>
	76	private HttpWebResponse _response;
	77
	78	/// <summary>
	79	/// This flag will help block the main synchroneous method, in case we run in synchroneous mode
	80	/// </summary>
	81	public static ManualResetEvent _allDone = new ManualResetEvent(false);
	82
	83	/// <summary>
	84	/// Default time out period
	85	/// </summary>
	86	private const int DefaultTimeout = 10*1000; // 10 seconds timeout
	87
	88	/// <summary>
	89	/// Default Buffer size of a block requested from the web-server
	90	/// </summary>
	91	private const int BufferSize = 4096; // Read blocks of 4 KB.
	92
	93
	94	/// <summary>
	95	/// if an exception occours during async processing, we need to save it, so it can be
	96	/// rethrown on the primary thread;
	97	/// </summary>
	98	private Exception _asyncException;
	99
	100	#endregion member variables
	101
	102	#region constructors
	103
	104	/// <summary>
	105	/// Instantiate a new RestClient
	106	/// </summary>
	107	/// <param name="url">Web-service to query, e.g. http://osgrid.org:8003</param>
	108	public RestClient(string url)
	109	{
	110	_url = url;
	111	_readbuf = new byte[BufferSize];
	112	_resource = new MemoryStream();
	113	_request = null;
	114	_response = null;
	115	_lock = new object();
	116	}
	117
	118	private object _lock;
	119
	120	#endregion constructors
	121
	122	/// <summary>
	123	/// Add a path element to the query, e.g. assets
	124	/// </summary>
	125	/// <param name="element">path entry</param>
	126	public void AddResourcePath(string element)
	127	{
	128	if (isSlashed(element))
	129	_pathElements.Add(element.Substring(0, element.Length - 1));
	130	else
	131	_pathElements.Add(element);
	132	}
	133
	134	/// <summary>
	135	/// Add a query parameter to the Url
	136	/// </summary>
	137	/// <param name="name">Name of the parameter, e.g. min</param>
	138	/// <param name="value">Value of the parameter, e.g. 42</param>
	139	public void AddQueryParameter(string name, string value)
	140	{
	141	_parameterElements.Add(HttpUtility.UrlEncode(name), HttpUtility.UrlEncode(value));
	142	}
	143
	144	/// <summary>
	145	/// Add a query parameter to the Url
	146	/// </summary>
	147	/// <param name="name">Name of the parameter, e.g. min</param>
	148	public void AddQueryParameter(string name)
	149	{
	150	_parameterElements.Add(HttpUtility.UrlEncode(name), null);
	151	}
	152
	153	/// <summary>
	154	/// Web-Request method, e.g. GET, PUT, POST, DELETE
	155	/// </summary>
	156	public string RequestMethod
	157	{
	158	get { return _method; }
	159	set { _method = value; }
	160	}
	161
	162	/// <summary>
	163	/// True if string contains a trailing slash '/'
	164	/// </summary>
	165	/// <param name="s">string to be examined</param>
	166	/// <returns>true if slash is present</returns>
	167	private bool isSlashed(string s)
	168	{
	169	return s.Substring(s.Length - 1, 1) == "/";
	170	}
	171
	172	/// <summary>
	173	/// Build a Uri based on the initial Url, path elements and parameters
	174	/// </summary>
	175	/// <returns>fully constructed Uri</returns>
	176	private Uri buildUri()
	177	{
	178	StringBuilder sb = new StringBuilder();
	179	sb.Append(_url);
	180
	181	foreach (string e in _pathElements)
	182	{
	183	sb.Append("/");
	184	sb.Append(e);
	185	}
	186
	187	bool firstElement = true;
	188	foreach (KeyValuePair<string, string> kv in _parameterElements)
	189	{
	190	if (firstElement)
	191	{
	192	sb.Append("?");
	193	firstElement = false;
	194	}
	195	else
	196	sb.Append("&");
	197
	198	sb.Append(kv.Key);
	199	if (kv.Value != null && kv.Value.Length != 0)
	200	{
	201	sb.Append("=");
	202	sb.Append(kv.Value);
	203	}
	204	}
	205	realuri = sb.ToString();
	206	//m_log.InfoFormat("[REST CLIENT]: RestURL: {0}", realuri);
	207	return new Uri(sb.ToString());
	208	}
	209
	210	#region Async communications with server
	211
	212	/// <summary>
	213	/// Async method, invoked when a block of data has been received from the service
	214	/// </summary>
	215	/// <param name="ar"></param>
	216	private void StreamIsReadyDelegate(IAsyncResult ar)
	217	{
	218	try
	219	{
	220	Stream s = (Stream) ar.AsyncState;
	221	int read = s.EndRead(ar);
	222
	223	if (read > 0)
	224	{
	225	_resource.Write(_readbuf, 0, read);
	226	IAsyncResult asynchronousResult =
	227	s.BeginRead(_readbuf, 0, BufferSize, new AsyncCallback(StreamIsReadyDelegate), s);
	228
	229	// TODO! Implement timeout, without killing the server
	230	//ThreadPool.RegisterWaitForSingleObject(asynchronousResult.AsyncWaitHandle, new WaitOrTimerCallback(TimeoutCallback), _request, DefaultTimeout, true);
	231	}
	232	else
	233	{
	234	s.Close();
	235	_allDone.Set();
	236	}
	237	}
	238	catch (Exception e)
	239	{
	240	_allDone.Set();
	241	_asyncException = e;
	242	}
	243	}
	244
	245	#endregion Async communications with server
	246
	247	/// <summary>
	248	/// Perform synchroneous request
	249	/// </summary>
	250	public Stream Request()
	251	{
	252	lock (_lock)
	253	{
	254	_request = (HttpWebRequest) WebRequest.Create(buildUri());
	255	_request.KeepAlive = false;
	256	_request.ContentType = "application/xml";
	257	_request.Timeout = 200000;
	258	_asyncException = null;
	259
	260	// IAsyncResult responseAsyncResult = _request.BeginGetResponse(new AsyncCallback(ResponseIsReadyDelegate), _request);
	261	_response = (HttpWebResponse) _request.GetResponse();
	262	Stream src = _response.GetResponseStream();
	263	int length = src.Read(_readbuf, 0, BufferSize);
	264	while (length > 0)
	265	{
	266	_resource.Write(_readbuf, 0, length);
	267	length = src.Read(_readbuf, 0, BufferSize);
	268	}
	269
	270
	271	// TODO! Implement timeout, without killing the server
	272	// this line implements the timeout, if there is a timeout, the callback fires and the request becomes aborted
	273	//ThreadPool.RegisterWaitForSingleObject(responseAsyncResult.AsyncWaitHandle, new WaitOrTimerCallback(TimeoutCallback), _request, DefaultTimeout, true);
	274
	275	// _allDone.WaitOne();
	276	if (_response != null)
	277	_response.Close();
	278	if (_asyncException != null)
	279	throw _asyncException;
	280
	281	if (_resource != null)
	282	{
	283	_resource.Flush();
	284	_resource.Seek(0, SeekOrigin.Begin);
	285	}
	286
	287	return _resource;
	288	}
	289	}
	290
	291	public Stream Request(Stream src)
	292	{
	293	_request = (HttpWebRequest) WebRequest.Create(buildUri());
	294	_request.KeepAlive = false;
	295	_request.ContentType = "application/xml";
	296	_request.Timeout = 900000;
	297	_request.Method = RequestMethod;
	298	_asyncException = null;
	299	_request.ContentLength = src.Length;
	300
	301	m_log.InfoFormat("[REST]: Request Length {0}", _request.ContentLength);
	302	m_log.InfoFormat("[REST]: Sending Web Request {0}", buildUri());
	303	src.Seek(0, SeekOrigin.Begin);
	304	m_log.Info("[REST]: Seek is ok");
	305	Stream dst = _request.GetRequestStream();
	306	m_log.Info("[REST]: GetRequestStream is ok");
	307
	308	byte[] buf = new byte[1024];
	309	int length = src.Read(buf, 0, 1024);
	310	m_log.Info("[REST]: First Read is ok");
	311	while (length > 0)
	312	{
	313	dst.Write(buf, 0, length);
	314	length = src.Read(buf, 0, 1024);
	315	}
	316
	317	_response = (HttpWebResponse) _request.GetResponse();
	318
	319	// IAsyncResult responseAsyncResult = _request.BeginGetResponse(new AsyncCallback(ResponseIsReadyDelegate), _request);
	320
	321	// TODO! Implement timeout, without killing the server
	322	// this line implements the timeout, if there is a timeout, the callback fires and the request becomes aborted
	323	//ThreadPool.RegisterWaitForSingleObject(responseAsyncResult.AsyncWaitHandle, new WaitOrTimerCallback(TimeoutCallback), _request, DefaultTimeout, true);
	324
	325	return null;
	326	}
	327
	328	#region Async Invocation
	329
	330	public IAsyncResult BeginRequest(AsyncCallback callback, object state)
	331	{
	332	/// <summary>
	333	/// In case, we are invoked asynchroneously this object will keep track of the state
	334	/// </summary>
	335	AsyncResult<Stream> ar = new AsyncResult<Stream>(callback, state);
	336	ThreadPool.QueueUserWorkItem(RequestHelper, ar);
	337	return ar;
	338	}
	339
	340	public Stream EndRequest(IAsyncResult asyncResult)
	341	{
	342	AsyncResult<Stream> ar = (AsyncResult<Stream>) asyncResult;
	343
	344	// Wait for operation to complete, then return result or
	345	// throw exception
	346	return ar.EndInvoke();
	347	}
	348
	349	private void RequestHelper(Object asyncResult)
	350	{
	351	// We know that it's really an AsyncResult<DateTime> object
	352	AsyncResult<Stream> ar = (AsyncResult<Stream>) asyncResult;
	353	try
	354	{
	355	// Perform the operation; if sucessful set the result
	356	Stream s = Request();
	357	ar.SetAsCompleted(s, false);
	358	}
	359	catch (Exception e)
	360	{
	361	// If operation fails, set the exception
	362	ar.HandleException(e, false);
	363	}
	364	}
	365
	366	#endregion Async Invocation
	367	}
	368	} \ No newline at end of file