Call WebService Method Using HttpWebRequest

I hacked together a quick function for calling a method in a WebService using the HttpWebRequest object in .NET. This method will return the result from the method call as a string, which you can then convert to whatever appropriate type you need. If the web method does not return a result, the method returns an empty-string. If the method fails for some reason, it returns null. I know, I should throw an exception, but this is a quick-n-dirty function.

public string MakeWebMethodRequest(string url, string webMethod, object [] parameters)
{
 bool returnsResult = false;
 string ns = "";
 string [] paramNames = new string[0];
 try
 {
  if ((!url.StartsWith("http://")) && (!url.StartsWith("https://")))
   url = "http://" + url;

  if (!url.EndsWith("?wsdl"))
   url += "?wsdl";
  System.Net.HttpWebRequest httpWebRequest = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(url);
  httpWebRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; .NET CLR 1.1.4322)";
  httpWebRequest.Timeout = 300000;
  httpWebRequest.Accept = "text/xml; charset=utf-8";

  System.Net.HttpWebResponse httpWebResponse = (System.Net.HttpWebResponse)httpWebRequest.GetResponse();

  StreamReader streamReader = new StreamReader(httpWebResponse.GetResponseStream());

  string result = streamReader.ReadToEnd();
  streamReader.Close();
  
  XmlDocument xDoc = new XmlDocument();
  xDoc.LoadXml(result);
  ns = xDoc.GetElementsByTagName("wsdl:definitions")[0].Attributes["targetNamespace"].Value;
  if (!ns.EndsWith("/")) ns += "/";
  foreach (XmlNode xNode in xDoc.GetElementsByTagName("s:element"))
  {
   if (xNode.Attributes["name"].Value.CompareTo(webMethod) == 0)
   {
    XmlNode complexNode = xNode.FirstChild;
    if (complexNode.HasChildNodes)
    {
     XmlNode seqNode = complexNode.FirstChild;
     if (seqNode.HasChildNodes)
     {
      //parameters...
      paramNames = new string [seqNode.ChildNodes.Count];
      int i = 0;
      foreach(XmlNode child in seqNode.ChildNodes)
      {
       paramNames[i] = child.Attributes["name"].Value;
       i++;
      }
     }
    }
    break;
   }
  }
  foreach (XmlNode xNode in xDoc.GetElementsByTagName("s:element"))
  {
   if (xNode.Attributes["name"].Value.CompareTo(webMethod + "Response") == 0)
   {
    XmlNode complexNode = xNode.FirstChild;
    if (complexNode.HasChildNodes)
    {
     returnsResult = true;
    }
    break;
   }
  }
 }
 catch
 {
  return null;
 }

 string xml = "";
 xml += "<?xml version=\"1.0\" encoding=\"utf-8\"?>";
 xml += "<soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" ";
 xml += "xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" ";
 xml += "xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">";
 xml += "<soap:Body>";

 xml += "<" + webMethod + " xmlns=\"" + ns + "\">";

 if (parameters != null)
 {
  if (parameters.Length == paramNames.Length)
  {
   for (int i = 0; i < parameters.Length; i++)
   {
    xml += "<" + paramNames[i] + ">";
   
    if (parameters[i].GetType().ToString().CompareTo("System.String") == 0)
    {
     xml += parameters[i].ToString().Replace("&", "&amp;").Replace("<", "&lt;").Replace(">", "&gt;");
    }
    else
    {
     xml += parameters[i].ToString();
    }
    xml += "</" + paramNames[i] + ">";
   }
  }
 }

 xml += "</" + webMethod + ">";

 xml += "</soap:Body>";
 xml += "</soap:Envelope>";

 try
 {
  System.Net.HttpWebRequest httpWebRequest = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(url);
  httpWebRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; .NET CLR 1.1.4322)";
  httpWebRequest.Headers.Add("SOAPAction", "\"" + ns + webMethod + "\"");
  httpWebRequest.Timeout = 300000;
  httpWebRequest.Method = "POST";

  // add the content type so we can handle form data
  httpWebRequest.ContentType = "text/xml; charset=utf-8";

  httpWebRequest.Accept = "text/xml; charset=utf-8";
  // we need to store the data into a byte array
  Byte [] postData = Encoding.UTF8.GetBytes(xml);

  httpWebRequest.ContentLength = postData.Length;
  System.IO.Stream tempStream;
  tempStream = httpWebRequest.GetRequestStream();
  // write the data to be posted to the Request Stream
  tempStream.Write(postData, 0, postData.Length);
  tempStream.Close();

  System.Net.HttpWebResponse httpWebResponse = (System.Net.HttpWebResponse)httpWebRequest.GetResponse();

  StreamReader streamReader = new StreamReader(httpWebResponse.GetResponseStream());

  string xmlresult = streamReader.ReadToEnd();
  streamReader.Close();

  if (returnsResult)
  {
   XmlDocument xDoc = new XmlDocument();
   xDoc.LoadXml(xmlresult);
   string result = xDoc.GetElementsByTagName(webMethod + "Result")[0].InnerText;
   return result.Replace("&amp;", "&").Replace("&lt;", "<").Replace("&gt;", ">");
  }
  else
  {
   return "";
  }
 }
 catch
 {
  return null;
 }
}