HTTPget sync and async version

Sometimes you need to read a remote ( or local ) web page for scraping the content or ajax save, etc.

Async version has been tested by calling it 10000 times, and watching the threads for leaks - no problems found. This is good when you want to do a lengthy process in the background, when the user is looking at the thanks page.

Here are a couple of functions:

        /// <summary>
        /// wraps up the .NET HttpWebRequest and HttpWebResponse to make a page request simpler
        /// </summary>
        /// <param name="URL">the URL to request (can be relative or absolute)</param>
        /// <param name="ErrorFormat">the string to return if there is an error. "URL" will be matched and replaced with the requested URL if it is found</param>
        /// <returns>the response as a string</returns>
        public static string HttpGet(string URL, string ErrorFormat)
        {
            return HttpGet(URL,ErrorFormat,Web.Request);
        }


        /// <summary>
        /// make an async call to a url, and don't return any result
        /// </summary>
        /// <param name="URL"></param>
        public static void HttpGetAsync(string URL)
        {
            Util.HttpGetAsync(URL,"HttpGet ERROR requesting: URL");
        }
        /// <summary>
        /// make an async call to a url, and don't return any result
        /// </summary>
        /// <param name="URL"></param>
        /// <param name="ErrorFormat"></param>
        public static void HttpGetAsync(string URL, string ErrorFormat)
        {
            //create the delegate
            HttpGetAsyncDelegate asyncAction = HttpGetAsyncAction;
            //invoke it asynchrnously, control passes to next statement
            asyncAction.BeginInvoke(URL,ErrorFormat,Web.Request,null,null);
        }

        private delegate void HttpGetAsyncDelegate(string URL, string ErrorFormat, HttpRequest req); //delegate for the action

        private static void HttpGetAsyncAction(string URL, string ErrorFormat, HttpRequest req)
        {
            Util.HttpGet(URL,ErrorFormat??"HttpGet ERROR requesting: URL",req);
        }
        /// <summary>
        /// wraps up the .NET HttpWebRequest and HttpWebResponse to make a page request simpler
        /// </summary>
        /// <param name="URL">the URL to request (can be relative or absolute)</param>
        /// <param name="ErrorFormat">the string to return if there is an error. "URL" will be matched and replaced with the requested URL if it is found</param>
        /// <returns>the response as a string</returns>
        public static string HttpGet(string URL, string ErrorFormat,  HttpRequest req)
        {
            string returnValue = "";
            
            // if no "http://" in URL then relative URL was meant
            if(!URL.StartsWith("http://"))
            {
                URL = URL.TrimStart(new Char[] {'/'}); // trim off a leading slash if there is one

                Uri currentUri = req.Url;
                //TODO: make the next line a bit more robust??
                string virtualPath = (ServerIs() != "LVE") ? currentUri.Segments[1] : ""; // this assumes dev and staging both use a virtual path

                URL = String.Format("http://{0}{1}{2}" + URL,
                                                        currentUri.Host,
                                                        currentUri.Segments[0],
                                                        virtualPath
                    );
            }
                        
            HttpWebRequest httpRequest = WebRequest.Create(URL) as HttpWebRequest;
            if (httpRequest != null)
            {
                httpRequest.Method = "GET";

                // MN 20100725 - experiment
                //if (async) {
                //  var asyncResponse = httpRequest.BeginGetResponse(null, null);
                //  httpRequest.EndGetResponse(asyncResponse);
                //}

                try
                {
                    HttpWebResponse httpResponse = httpRequest.GetResponse() as HttpWebResponse;
                    if (httpResponse != null)
                    {
                        StreamReader sr = new StreamReader(httpResponse.GetResponseStream());
                        returnValue = sr.ReadToEnd();
                        sr.Close();
                        httpResponse.Close();
                    }
                }
                catch
                {
                    // try and replace the URL if we find it - if not, just return the user's Error String
                    returnValue = ErrorFormat.Replace("URL", URL);
                }
            }
            return returnValue;
        }
        #endregion