/// <summary>
/// Callback method called when the "Download" method returns from an HTTPWebRequest.
/// </summary>
/// <param name="result">The result of the asynchronous operation.</param>
private void ResponseCallback(IAsyncResult result)
{
RequestState state = result.AsyncState as RequestState;
Feed parentFeed = state.Argument as Feed;
if (null != parentFeed)
{
HttpWebRequest request = state.Request as HttpWebRequest;
// Progress only if this download has not been timed out.
if (null != request)
{
// Retrieve response.
try
{
using (HttpWebResponse response = request.EndGetResponse(result) as HttpWebResponse)
{
if (null != response && response.StatusCode == HttpStatusCode.OK)
{
using (XmlReader reader = XmlReader.Create(response.GetResponseStream()))
{
// Collection to store all articles
Collection <Article> parsedArticles = _parser.ParseItems(reader, parentFeed);
// Raise event for a single feed downloaded.
if (null != SingleDownloadFinished)
{
SingleDownloadFinished(this, new SingleDownloadFinishedEventArgs(parentFeed, parsedArticles));
}
// Add to all downloads dictionary and raise AllDownloadsFinished if all async requests have finished.
Downloads.Add(parentFeed, parsedArticles);
CheckIfDone();
}
}
}
}
catch (WebException we)
{
if (we.Status == WebExceptionStatus.RequestCanceled)
{
// The web request was timed out. Let debug know it failed.
System.Diagnostics.Debug.WriteLine("ERROR: Feed \"" + parentFeed.FeedTitle + "\" was timed out.");
CheckIfDone();
return;
}
else if (we.Message == "The remote server returned an error: NotFound.")
{
// The web site did not respond. This means one of two things: Either the web site is bad, or you have no internet.
// If error code NotFound is received, then there is no connection. Throw the exception.
if ((we.Response as HttpWebResponse).StatusCode == HttpStatusCode.NotFound)
{
// WebTools throws an exception if without connection. Warn the user.
CheckIfDone();
if (!IsDownloading)
{
Deployment.Current.Dispatcher.BeginInvoke(() =>
{
MessageBox.Show("FeedCast is unable to reach a connection. Please check your network connectivity.");
});
}
}
// If error code InternalServerError is received, then it is a faulty site.
else
{
System.Diagnostics.Debug.WriteLine("ERROR: Feed \"" + parentFeed.FeedTitle + "\" is faulty.");
CheckIfDone();
return;
}
}
else
{
// Unexpected web exception.
throw we;
}
}
}
}
}
/// <summary>
/// Downloads the provided List of Feeds.
/// You cannot call download while downloads are in progress.
/// </summary>
/// <param name="feeds">List of feeds to download.</param>
public void Download(IList <Feed> feeds)
{
// Clear any leftover stored articles/feeds in Downloads and _allRequests.
Downloads.Clear();
_allRequests.Clear();
// Set the timer for timeouts if parsing syndication feeds.
if (_parser is SynFeedParser)
{
int timeLimit;
if (Settings.InitialLaunchSetting)
{
timeLimit = 20000; // 20 second limit for initial launch.
}
else
{
timeLimit = 7500; // Otherwise, 7.5 second time limit.
}
TimerCallback tc = new TimerCallback(TimeoutConnections);
_timeout = new Timer(tc, this, timeLimit, Timeout.Infinite);
}
if (null != feeds && feeds.Count > 0)
{
lock (_lockObject)
{
_numOfRequests += feeds.Count;
}
IsDownloading = true;
// Download each separate feed.
foreach (Feed feed in feeds)
{
string feedURI = feed.FeedBaseURI;
if (null != feedURI)
{
HttpWebRequest feedRequest = HttpWebRequest.Create(feedURI) as HttpWebRequest;
// Check if the application has been set to wifi-only or not.
if (WifiOnly)
{
feedRequest.SetNetworkRequirement(NetworkSelectionCharacteristics.NonCellular);
}
if (null != feedRequest)
{
RequestState feedState = new RequestState()
{
// Change the owner to the parent HTTPWebRequest.
Request = feedRequest,
// Change the argument to be the current feed to be downloaded.
Argument = feed,
};
// Begin download.
feedRequest.BeginGetResponse(ResponseCallback, feedState);
// Keep track of the download.
_allRequests.Add(feed, feedRequest);
}
}
}
}
}
