Replace WebClient to prevent timeouts?

Question

I am working on a C # project that uses a common XML stream for computation. I originally used XmlDocument.Load, but ported to WebClient.DownloadString so that I can include headers in my request. The channel that I access usually responds quickly, but every time now it does not respond again during the waiting period of the WebClient object, and I get an exception. Here is my code:

XmlDocument xmlDoc = new XmlDocument(); Webclient client = new WebClient(); client.Headers["User-Agent"] = "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/535.1 (KHTML, like Gecko) Chrome/14.0.835.202 Safari/535.1"; client.Headers["Accept"] = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"; string data = client.DownloadString(/*URL*/); xmlDoc.LoadXml(data); 

I read that you cannot change the WebClient timeout property, and people who have this problem should use HttpWebRequest instead. Unfortunately, I do not know how to implement this, since it allows me to use my headers and send this result to xmlDoc. Due to the nature of this application, I don't care how long it takes to get the data; I can handle a user warning.

What is the best way to do this?

Answer 1

To do this, you can use the derived WebClient class, which simply adds the timeout you want for each fetch:

 public class TimeoutWebClient : WebClient { protected override WebRequest GetWebRequest(Uri address) { HttpWebRequest request = (HttpWebRequest)base.GetWebRequest(address); request.Timeout = 60000; //1 minute timeout return request; } } 

If now you use TimeoutWebClient instead of WebClient , you will get the required timeout. If the custom headers you need are the same for each request, you can add them here, and your calling code remains very clean.

Answer 2

 XmlDocument xmlDoc = new XmlDocument(); HttpWebRequest request = new (HttpWebRequest)WebRequest.Create(/*URL*/); request.Headers = new WebHeaderCollection(); // fill in request.Headers... // The response is presented as a stream. Wrap it in a StreamReader that // xmlDoc.LoadXml can accept. xmlDoc.LoadXml(new StreamReader(request.GetResponse().GetResponseStream()); 

Answer 3

You can just catch the exception and then reissue the request. You might want to add some other logic to interrupt after some unsuccessful attempts.

 bool continue; do{ continue = false; try { string data = client.DownloadString(/*URL*/); } catch (WebException e) { continue = true; } } while(continue);