public Retriever(System.Windows.Forms.Control owner)
{
if (owner == null)
{
throw new System.ArgumentNullException("System.Windows.Forms.Control owner");
}
this.owner = owner;
this.timeoutInterval = System.TimeSpan.FromSeconds(60);
this.progressInterval = System.TimeSpan.FromSeconds(0.5);
this.state = RetrieverState.NotReady;
this.canceled = false;
this.monitor = new System.Windows.Forms.Timer();
this.monitor.Tick += new System.EventHandler(this.monitorTick);
}
// This function must be called by the client application to initiate retrieval.
public void Start()
{
if (this.state == RetrieverState.NotReady)
{
throw new RetrieverStateException(
"Retriever requires the URI to be set before calling Start().");
}
if (this.state == RetrieverState.Retrieving)
{
throw new RetrieverStateException("Retrieval already in progress.");
}
try
{
this.startTime = System.DateTime.Now;
this.previousProgressTime = this.startTime;
this.webRequest = System.Net.WebRequest.Create(this.request.Uri);
// Handle any proxy the system may have defined.
System.Net.WebProxy proxy = System.Net.WebProxy.GetDefaultProxy();
if (proxy.Address != null)
{
this.webRequest.Proxy = proxy;
}
this.webRequest.BeginGetResponse(
new System.AsyncCallback(this.onRetrieval), this);
// Compute an interval to check on progress, but make sure it's
// at least some reasonable minimum: say, 10 milliseconds.
ulong monitorInterval = (ulong)System.Math.Min(
this.timeoutInterval.Milliseconds,
this.progressInterval.Milliseconds);
this.monitor.Interval = (int)System.Math.Max(monitorInterval, 10);
this.monitor.Start();
this.canceled = false;
this.state = RetrieverState.Retrieving;
}
catch (System.Exception e)
{
throw e;
}
}
private void endRequest()
{
if (this.monitor.Enabled)
{
this.monitor.Stop();
}
try
{
if (this.state == RetrieverState.Retrieving)
{
this.webRequest.Abort();
}
}
finally
{
this.state = RetrieverState.Done;
}
}