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/*
* Copyright (c) Contributors, http://opensimulator.org/
* See CONTRIBUTORS.TXT for a full list of copyright holders.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the OpenSimulator Project nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
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;
using OpenSim.Framework.ServiceAuth;
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 synchronously and asynchronously.
///
/// Internally the implementation works as a two stage asynchronous web-client.
/// When the request is initiated, RestClient will query asynchronously 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 asynchronous requests will be triggered, in an attempt to read of the response
/// object into a memorystream as a sequence of asynchronous 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 itself can be
/// invoked by the caller in either synchronous mode or asynchronous modes.
/// </remarks>
public class RestClient : IDisposable
{
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 resulting 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
#region Dispose
private bool disposed = false;
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
protected virtual void Dispose(bool disposing)
{
if (disposed)
return;
if (disposing)
{
_resource.Dispose();
}
disposed = true;
}
#endregion Dispose
/// <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)
{
try
{
_parameterElements.Add(HttpUtility.UrlEncode(name), HttpUtility.UrlEncode(value));
}
catch (ArgumentException)
{
m_log.Error("[REST]: Query parameter " + name + " is already added.");
}
catch (Exception e)
{
m_log.Error("[REST]: An exception was raised adding query parameter to dictionary. Exception: {0}",e);
}
}
/// <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)
{
try
{
_parameterElements.Add(HttpUtility.UrlEncode(name), null);
}
catch (ArgumentException)
{
m_log.Error("[REST]: Query parameter " + name + " is already added.");
}
catch (Exception e)
{
m_log.Error("[REST]: An exception was raised adding query parameter to dictionary. Exception: {0}",e);
}
}
/// <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 static 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 (!string.IsNullOrEmpty(kv.Value))
{
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);
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 a synchronous request
/// </summary>
public Stream Request()
{
return Request(null);
}
/// <summary>
/// Perform a synchronous request
/// </summary>
public Stream Request(IServiceAuth auth)
{
lock (_lock)
{
_request = (HttpWebRequest) WebRequest.Create(buildUri());
_request.KeepAlive = false;
_request.ContentType = "application/xml";
_request.Timeout = 200000;
_request.Method = RequestMethod;
_asyncException = null;
if (auth != null)
auth.AddAuthorization(_request.Headers);
int reqnum = WebUtil.RequestNumber++;
if (WebUtil.DebugLevel >= 3)
m_log.DebugFormat("[LOGHTTP]: HTTP OUT {0} REST {1} to {2}", reqnum, _request.Method, _request.RequestUri);
// IAsyncResult responseAsyncResult = _request.BeginGetResponse(new AsyncCallback(ResponseIsReadyDelegate), _request);
try
{
using (_response = (HttpWebResponse) _request.GetResponse())
{
using (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();
}
}
}
catch (WebException e)
{
using (HttpWebResponse errorResponse = e.Response as HttpWebResponse)
{
if (null != errorResponse && HttpStatusCode.NotFound == errorResponse.StatusCode)
{
// This is often benign. E.g., requesting a missing asset will return 404.
m_log.DebugFormat("[REST CLIENT] Resource not found (404): {0}", _request.Address.ToString());
}
else
{
m_log.Error(string.Format("[REST CLIENT] Error fetching resource from server: {0} ", _request.Address.ToString()), e);
}
}
return null;
}
if (_asyncException != null)
throw _asyncException;
if (_resource != null)
{
_resource.Flush();
_resource.Seek(0, SeekOrigin.Begin);
}
if (WebUtil.DebugLevel >= 5)
WebUtil.LogResponseDetail(reqnum, _resource);
return _resource;
}
}
public Stream Request(Stream src, IServiceAuth auth)
{
_request = (HttpWebRequest) WebRequest.Create(buildUri());
_request.KeepAlive = false;
_request.ContentType = "application/xml";
_request.Timeout = 900000;
_request.Method = RequestMethod;
_asyncException = null;
_request.ContentLength = src.Length;
if (auth != null)
auth.AddAuthorization(_request.Headers);
src.Seek(0, SeekOrigin.Begin);
int reqnum = WebUtil.RequestNumber++;
if (WebUtil.DebugLevel >= 3)
m_log.DebugFormat("[LOGHTTP]: HTTP OUT {0} REST {1} to {2}", reqnum, _request.Method, _request.RequestUri);
if (WebUtil.DebugLevel >= 5)
WebUtil.LogOutgoingDetail(string.Format("SEND {0}: ", reqnum), src);
Stream dst = _request.GetRequestStream();
byte[] buf = new byte[1024];
int length = src.Read(buf, 0, 1024);
while (length > 0)
{
dst.Write(buf, 0, length);
length = src.Read(buf, 0, 1024);
}
try
{
_response = (HttpWebResponse)_request.GetResponse();
}
catch (WebException e)
{
m_log.WarnFormat("[REST]: Request {0} {1} failed with status {2} and message {3}",
RequestMethod, _request.RequestUri, e.Status, e.Message);
return null;
}
catch (Exception e)
{
m_log.WarnFormat(
"[REST]: Request {0} {1} failed with exception {2} {3}",
RequestMethod, _request.RequestUri, e.Message, e.StackTrace);
return null;
}
if (WebUtil.DebugLevel >= 5)
{
using (Stream responseStream = _response.GetResponseStream())
{
using (StreamReader reader = new StreamReader(responseStream))
{
string responseStr = reader.ReadToEnd();
WebUtil.LogResponseDetail(reqnum, responseStr);
}
}
}
_response.Close();
// 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);
Util.FireAndForget(RequestHelper, ar, "RestClient.BeginRequest");
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(null);
ar.SetAsCompleted(s, false);
}
catch (Exception e)
{
// If operation fails, set the exception
ar.HandleException(e, false);
}
}
#endregion Async Invocation
}
internal class SimpleAsyncResult : IAsyncResult
{
private readonly AsyncCallback m_callback;
/// <summary>
/// Is process completed?
/// </summary>
/// <remarks>Should really be boolean, but VolatileRead has no boolean method</remarks>
private byte m_completed;
/// <summary>
/// Did process complete synchronously?
/// </summary>
/// <remarks>I have a hard time imagining a scenario where this is the case, again, same issue about
/// booleans and VolatileRead as m_completed
/// </remarks>
private byte m_completedSynchronously;
private readonly object m_asyncState;
private ManualResetEvent m_waitHandle;
private Exception m_exception;
internal SimpleAsyncResult(AsyncCallback cb, object state)
{
m_callback = cb;
m_asyncState = state;
m_completed = 0;
m_completedSynchronously = 1;
}
#region IAsyncResult Members
public object AsyncState
{
get { return m_asyncState; }
}
public WaitHandle AsyncWaitHandle
{
get
{
if (m_waitHandle == null)
{
bool done = IsCompleted;
ManualResetEvent mre = new ManualResetEvent(done);
if (Interlocked.CompareExchange(ref m_waitHandle, mre, null) != null)
{
mre.Close();
}
else
{
if (!done && IsCompleted)
{
m_waitHandle.Set();
}
}
}
return m_waitHandle;
}
}
public bool CompletedSynchronously
{
get { return Thread.VolatileRead(ref m_completedSynchronously) == 1; }
}
public bool IsCompleted
{
get { return Thread.VolatileRead(ref m_completed) == 1; }
}
#endregion
#region class Methods
internal void SetAsCompleted(bool completedSynchronously)
{
m_completed = 1;
if (completedSynchronously)
m_completedSynchronously = 1;
else
m_completedSynchronously = 0;
SignalCompletion();
}
internal void HandleException(Exception e, bool completedSynchronously)
{
m_completed = 1;
if (completedSynchronously)
m_completedSynchronously = 1;
else
m_completedSynchronously = 0;
m_exception = e;
SignalCompletion();
}
private void SignalCompletion()
{
if (m_waitHandle != null) m_waitHandle.Set();
if (m_callback != null) m_callback(this);
}
public void EndInvoke()
{
// This method assumes that only 1 thread calls EndInvoke
if (!IsCompleted)
{
// If the operation isn't done, wait for it
AsyncWaitHandle.WaitOne();
AsyncWaitHandle.Close();
m_waitHandle.Close();
m_waitHandle = null; // Allow early GC
}
// Operation is done: if an exception occured, throw it
if (m_exception != null) throw m_exception;
}
#endregion
}
internal class AsyncResult<T> : SimpleAsyncResult
{
private T m_result = default(T);
public AsyncResult(AsyncCallback asyncCallback, Object state) :
base(asyncCallback, state)
{
}
public void SetAsCompleted(T result, bool completedSynchronously)
{
// Save the asynchronous operation's result
m_result = result;
// Tell the base class that the operation completed
// sucessfully (no exception)
base.SetAsCompleted(completedSynchronously);
}
public new T EndInvoke()
{
base.EndInvoke();
return m_result;
}
}
}
|