C # How to send an HttpPost request to call WebService

Copy codeThe Code is as follows: void UpdateContactSign ()
{
String ServerPage = "http: // localhost/WebService/MyService. asmx ";
Try
{
// ServerPage + = "? Op = TangramAction ";
ServerPage + = "/MyAction"; // MyAction is a method in WebService.
String strXml = "<a ObjID = \" 9 \ "> </a>",; // The first parameter
String strData = "ContactSign | 990011 | my data"; // The second parameter.
String res = HttpConnectToServer (ServerPage, strXml, strData );
// MessageBox. Show (res );
}
Catch (Exception ex)
{

}
}

// Send a message to the server
Public string HttpConnectToServer (string ServerPage, string strXml, string strData)
{
String postData = "strXml =" + strXml + "& strData =" + strData;

Byte [] dataArray = Encoding. Default. GetBytes (postData );
// Create a request
HttpWebRequest request = (HttpWebRequest) HttpWebRequest. Create (ServerPage );
Request. Method = "POST ";
Request. ContentLength = dataArray. Length;
Request. ContentType = "application/x-www-form-urlencoded ";
// Create an input stream
Stream dataStream = null;
Try
{
DataStream = request. GetRequestStream ();
}
Catch (Exception)
{
Return null; // failed to connect to the server
}

// Send the request
DataStream. Write (dataArray, 0, dataArray. Length );
DataStream. Close ();
// Read the returned message
String res = string. Empty;
Try
{
HttpWebResponse response = (HttpWebResponse) request. GetResponse ();
StreamReader reader = new StreamReader (response. GetResponseStream (), Encoding. UTF8 );
Res = reader. ReadToEnd ();
Reader. Close ();
}
Catch (Exception ex)
{
Return null; // failed to connect to the server
}
Return res;
}