/// <summary>
/// Called for first web request.
/// </summary>
/// <param name="requestParameter">Could be modified for each subsequent request</param>
/// <param name="webRequestComplete"></param>
/// <param name="webRequestException"></param>
/// <param name="webRequestStart"></param>
/// <param name="webRequestProgress"></param>
/// <param name="priority"></param>
private RequestState DoQueueRequest(RequestParameter requestParameter,
RequestStartCallback webRequestStart,
RequestCompleteCallback webRequestComplete,
RequestExceptionCallback webRequestException,
RequestProgressCallback webRequestProgress,
int priority)
{
if (requestParameter == null)
{
throw new ArgumentNullException("requestParameter");
}
if (_queuedRequests.Contains(requestParameter.RequestUri.CanonicalizedUri()))
{
return(null); // httpRequest already there
}
_queuedRequests.Add(requestParameter.RequestUri.CanonicalizedUri(), null);
var webRequest = PrepareRequest(requestParameter);
RequestState state = new RequestState(webRequest, priority, requestParameter);
state.WebRequestBeforeStart += webRequestStart;
state.WebRequestCompleted += webRequestComplete;
state.WebRequestException += webRequestException;
state.WebRequestProgress += webRequestProgress;
PerformHttpRequestAsync(state, priority);
return(state);
}
/// <summary>
/// Used to make GET requests for multiple URLs asynchronously
/// </summary>
/// <param name="requests">The URLs to be fetched</param>
/// <param name="webRequestStart">callback invoked when each GET request starts</param>
/// <param name="webRequestComplete">callback invoked when each GET request completes</param>
/// <param name="webRequestException">callback invoked when each GET request fails</param>
/// <exception cref="NotSupportedException">The request scheme specified in address has not been registered.</exception>
/// <exception cref="ArgumentNullException">The requestParameter is a null reference</exception>
public void QueueRequestsAsync(List <RequestParameter> requests,
RequestStartCallback webRequestStart,
RequestCompleteCallback webRequestComplete,
RequestExceptionCallback webRequestException)
{
const int priority = 10; // needed for additional requests
// Parallel options object specifies scheduler and max concurrent threads
ParallelOptions options = new ParallelOptions()
{
TaskScheduler = _scheduler, MaxDegreeOfParallelism = _scheduler.MaximumConcurrencyLevel
};
// Create an instance of the RequestState and perform the HTTP request for each of the request parameters
Parallel.ForEach(requests, options,
request =>
{
if (request != null && !_queuedRequests.Contains(request.RequestUri.CanonicalizedUri()))
{
_queuedRequests.Add(request.RequestUri.CanonicalizedUri(), null);
var webRequest = PrepareRequest(request);
var state = new RequestState(webRequest, priority, request);
state.WebRequestBeforeStart += webRequestStart;
state.WebRequestCompleted += webRequestComplete;
state.WebRequestException += webRequestException;
PerformHttpRequest(state);
}
});
}
/// <summary>
/// Used to a queue an HTTP request for processing
/// </summary>
/// <param name="requestParameter"></param>
/// <param name="webRequestComplete"></param>
/// <param name="webRequestException"></param>
/// <param name="webRequestStart"></param>
/// <param name="priority"></param>
/// <exception cref="NotSupportedException">The request scheme specified in address has not been registered.</exception>
/// <exception cref="ArgumentNullException">The requestParameter is a null reference</exception>
/// <exception cref="System.Security.SecurityException">The caller does not have permission to connect to the requested URI or a URI that the request is redirected to.</exception>
internal RequestState QueueRequest(RequestParameter requestParameter,
RequestStartCallback webRequestStart,
RequestCompleteCallback webRequestComplete,
RequestExceptionCallback webRequestException,
int priority)
{
return
(DoQueueRequest(requestParameter, webRequestStart, webRequestComplete,
webRequestException, null, priority));
}