public IAsyncResult BeginGetShippingRatesAsync(decimal weight, string originZipCode, string destinationZipCode, AsyncCallback callback, object state)
{
// create object that will store results
AsyncResult<ShippingRate[]> asyncResult = new AsyncResult<ShippingRate[]>(callback, state);
ShippingRatesRequest request = new ShippingRatesRequest(asyncResult, 3);
// launch asynchronous requests, which will complete in parallel
WebRequest fedExRequest = CreateFedExRequest(weight, originZipCode, destinationZipCode);
fedExRequest.BeginGetResponse(ar => FedExCallback(request, fedExRequest, ar), null);
WebRequest upsRequest = CreateUpsRequest(weight, originZipCode, destinationZipCode);
upsRequest.BeginGetResponse(ar => UpsCallback(request, upsRequest, ar), null);
WebRequest uspsRequest = CreateUspsRequest(weight, originZipCode, destinationZipCode);
uspsRequest.BeginGetResponse(ar => UspsCallback(request, uspsRequest, ar), null);
// return IAsyncResult implementation to client
return asyncResult;
}
public IAsyncResult BeginGetResponse(AsyncCallback callback, object state)
{
AsyncResult<WebResponse> asyncResult = new AsyncResult<WebResponse>(callback, state);
ThreadPool.QueueUserWorkItem(_ => asyncResult.Finish(GetResponse(), false));
return asyncResult;
}
public ShippingRatesRequest(AsyncResult<ShippingRate[]> asyncResult, int outstandingRequests)
{
m_lock = new object();
m_rates = new List<ShippingRate>();
m_asyncResult = asyncResult;
m_outstandingRequests = outstandingRequests;
}
public IAsyncResult BeginGetRequestStream(AsyncCallback callback, object state)
{
AsyncResult<Stream> asyncResult = new AsyncResult<Stream>(callback, state);
ThreadPool.QueueUserWorkItem(_ => asyncResult.Finish(new MemoryStream(), false));
return asyncResult;
}