/// <summary>
/// Retrieves the RSS feed for a particular subscription then converts
/// the blog posts or articles to an arraylist of items. The http requests are async calls.
/// </summary>
/// <param name="feedUrl">The URL of the feed to download</param>
/// <param name="forceDownload">Flag indicates whether cached feed items
/// can be returned or whether the application must fetch resources from
/// the web</param>
/// <param name="manual">Flag indicates whether the call was initiated by user (true), or
/// by automatic refresh timer (false)</param>
/// <exception cref="ApplicationException">If the RSS feed is not version 0.91, 1.0 or 2.0</exception>
/// <exception cref="XmlException">If an error occured parsing the RSS feed</exception>
/// <exception cref="ArgumentNullException">If feedUrl is a null reference</exception>
/// <exception cref="UriFormatException">If an error occurs while attempting to format the URL as an Uri</exception>
/// <returns>true, if the request really was queued up</returns>
/// <remarks>Result arraylist is returned by OnUpdatedFeed event within UpdatedFeedEventArgs</remarks>
// [MethodImpl(MethodImplOptions.Synchronized)]
public override bool AsyncGetItemsForFeed(string feedUrl, bool forceDownload, bool manual)
{
if (feedUrl == null || feedUrl.Trim().Length == 0)
{
throw new ArgumentNullException("feedUrl");
}
string etag = null;
bool requestQueued = false;
int priority = 10;
if (forceDownload)
{
priority += 100;
}
if (manual)
{
priority += 1000;
}
Uri feedUri = new Uri(feedUrl);
NewsFeed theFeed = null;
//see if we've retrieved the news feed before
if (feedsTable.ContainsKey(feedUri.CanonicalizedUri()))
{
theFeed = feedsTable[feedUri.CanonicalizedUri()] as NewsFeed;
}
if (theFeed == null) //feed list is corrupted
{
return(false);
}
// raise event only if we "really" go over the wire for an update:
RaiseOnUpdateFeedStarted(feedUri, forceDownload, priority);
//DateTime lastRetrieved = DateTime.MinValue;
DateTime lastModified = DateTime.MinValue;
if (itemsTable.ContainsKey(feedUrl))
{
etag = theFeed.etag;
lastModified = (theFeed.lastretrievedSpecified ? theFeed.lastretrieved : theFeed.lastmodified);
}
Dictionary <string, string> parameters = new Dictionary <string, string>();
parameters.Add("viewer_id", this.facebookUserId);
parameters.Add("session_key", this.sessionKey);
parameters.Add("method", "stream.get");
/* FQL
* string query = String.Format("?query=select post_id, source_id, created_time, actor_id, target_id, app_id, message, attachment, comments, likes, permalink, attribution, type from stream where filter_key in (select filter_key FROM stream_filter where uid = {0} and type = 'newsfeed') and created_time >= {1} order by created_time desc limit 50", facebookUserId, updatedTime);
* parameters = "&v=1.0&method=fql.query&format=JSON&call_id={0}&session_key={1}&api_key={2}&sig={3}";
*/
string reqUrl = feedUrl + "?" + CreateHTTPParameterList(parameters, false /* useJson */);
Uri reqUri = new Uri(reqUrl);
try
{
try
{
if ((!forceDownload) || Offline)
{
GetCachedItemsForFeed(feedUri.CanonicalizedUri()); //load feed into itemsTable
RaiseOnUpdatedFeed(feedUri, null, RequestResult.NotModified, priority, false);
return(false);
}
}
catch (XmlException xe)
{
//cache file is corrupt
Trace("Unexpected error retrieving cached feed '{0}': {1}", feedUrl, xe.ToDescriptiveString());
}
ICredentials c = null;
RequestParameter reqParam =
RequestParameter.Create(reqUri, this.UserAgent, this.Proxy, c, lastModified, etag);
reqParam = RequestParameter.Create(false, reqParam);
AsyncWebRequest.QueueRequest(reqParam,
OnRequestStart,
OnRequestComplete,
OnRequestException, priority);
requestQueued = true;
}
catch (Exception e)
{
Trace("Unexpected error on QueueRequest(), processing feed '{0}': {1}", feedUrl, e.ToDescriptiveString());
RaiseOnUpdateFeedException(feedUrl, e, priority);
}
return(requestQueued);
}