C# - Throw an exception if can't connect to remove server

I am trying to get an exception thrown if the function in my method fails, my code is as follows so far:

 if (sourceFile.Exists)
            // Would be nice to add ticker / spinner, while the file header on the remote server is being read!!
            {
                var request = (HttpWebRequest)WebRequest.Create(@"http://google.com/test.zip");
                request.Method = "HEAD";
                var response = (HttpWebResponse)request.GetResponse();

            开发者_StackOverflow社区    if (response.LastModified > sourceFile.LastWriteTime)
                {

                    Download_Click(sender, e);

                    // use response.GetStream() to download the file.
                }

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According to the HttpWebRequest docs, a WebException is thrown from GetResponse if the request times out or another error occurs while processing it.

You should be able to catch that in your code.

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try/catch HttpException

http://msdn.microsoft.com/en-us/library/system.web.httpexception.aspx