Question

When using the WebClient class you can check for errors and empty results by using

e.error != null

and

e.result == null

respectively. How would I handle this using the HttpWebRequest class? All examples seem to omit this yet its vital in applications.

Answer 1

The HttpWebRequest uses the IAsyncResult and Begin/End pairs for an operation.

You will have passed a Callback method delegate to Begin operation and then in that callback you call the End method for that operation. To catch an error that may have occured in the asynchronous part of the operation you place a try block around your call to the End method.

For example when calling BeginGetResponse you might pass this call back:-

 private void Callback(IAsyncResult asyncResult)
 {
     try 
     {
         HttpWebResponse resp =  (HttpWebResponse)myRequest.EndGetResponse(asyncResult);
     }
     catch (Exception e)
     {
         //Something bad happened during the request
     }

 }