How to use the HttpWebRequest class and the HttpWebResponse class to create appointment items on a computer that is running Exchange 2000 Server by using Visual C#

using System;
using System.Net;
using System.IO;            

namespace WebDavNET
{
    /// <summary>
    /// Summary description for Class1.
    /// </summary>
    class Class1
    {
    static void Main(string[] args)
    {
        try 
        {
            // TODO: Replace with the URL of an object on Exchange Server
            string sUri = "http://ExchServer/Exchange/Administrator/Calendar/testappt.eml";       

            System.Uri myUri = new System.Uri(sUri);
            HttpWebRequest HttpWRequest = (HttpWebRequest)WebRequest.Create(myUri);

            string strXMLNSInfo = "xmlns:g=\"DAV:\" " +
            " xmlns:e=\"http://schemas.microsoft.com/exchange/\"" +
            " xmlns:mapi=\"http://schemas.microsoft.com/mapi/\"" +
            " xmlns:x=\"xml:\" xmlns:cal=\"urn:schemas:calendar:\"" +
            " xmlns:dt=\"urn:uuid:c2f41010-65b3-11d1-a29f-00aa00c14882/\"" +
            " xmlns:mail=\"urn:schemas:httpmail:\">";

            string sQuery = "<?xml version=\"1.0\"?>" +
            "<g:propertyupdate " + strXMLNSInfo +
            "<g:set>" +
            "<g:prop>" +
            "<g:contentclass>urn:content-classes:appointment</g:contentclass>" +
            "<e:outlookmessageclass>IPM.Appointment</e:outlookmessageclass>" +
            "<mail:subject>Appointment Subject</mail:subject>" +
            "<cal:location>Appointment Location</cal:location>" +
            "<cal:dtstart dt:dt=\"dateTime.tz\">2001-12-27T22:00:00.000Z</cal:dtstart>" +
            "<cal:dtend dt:dt=\"dateTime.tz\">2001-12-27T22:30:00.000Z</cal:dtend>" +
            "<cal:instancetype dt:dt=\"int\">0</cal:instancetype>" +
            "<cal:busystatus>BUSY</cal:busystatus>" +
            "<cal:meetingstatus>TENTATIVE</cal:meetingstatus>" +
            "<cal:alldayevent dt:dt=\"boolean\">0</cal:alldayevent>" +
            "</g:prop>" +
            "</g:set>" +
            "</g:propertyupdate>";

            // Set credentials.
            // TODO: Replace with appropriate user credential
            NetworkCredential myCred = new NetworkCredential(@"DomainName\UserName", "UserPassword");
            CredentialCache myCredentialCache = new CredentialCache();
            myCredentialCache.Add(myUri, "Basic", myCred);
            HttpWRequest.Credentials = myCredentialCache;

            // Set headers.
            HttpWRequest.KeepAlive = false;
            HttpWRequest.Headers.Set("Pragma", "no-cache");
            HttpWRequest.Headers.Set("Translate", "f");
            HttpWRequest.ContentType =  "text/xml";
            HttpWRequest.ContentLength = sQuery.Length;

            //Set the request timeout to 5 minutes.
            HttpWRequest.Timeout = 300000;
            // set the request method
            HttpWRequest.Method = "PROPPATCH";
            
            // Store the data in a byte array.
            byte[] ByteQuery = System.Text.Encoding.ASCII.GetBytes(sQuery);
            HttpWRequest.ContentLength = ByteQuery.Length;
            Stream QueryStream = HttpWRequest.GetRequestStream();
            // Write the data to be posted to the request stream.
            QueryStream.Write(ByteQuery,0,ByteQuery.Length);
            QueryStream.Close();

            // Send the request and get the response.
            HttpWebResponse HttpWResponse = (HttpWebResponse)HttpWRequest.GetResponse();

            // Get the Status code.
            int iStatCode =  (int)HttpWResponse.StatusCode;
            string sStatus = iStatCode.ToString();
            Console.WriteLine("Status Code: {0}", sStatus);
            // Get the request headers
            string sReqHeaders = HttpWRequest.Headers.ToString();
            Console.WriteLine(sReqHeaders);

            // Read the response stream.
            Stream strm = HttpWResponse.GetResponseStream();
            StreamReader sr = new StreamReader(strm);
            string sText = sr.ReadToEnd();
            Console.WriteLine("Response: {0}", sText);

            // Close the stream.
            strm.Close();

            // Clean up
            myCred = null;
            myCredentialCache = null;
            HttpWRequest = null;
            HttpWResponse = null;
            QueryStream = null;
            strm = null;
            sr = null;
       
        }
        catch (Exception e)
        {
            Console.WriteLine("{0} Exception caught.", e);
        }
        }
    }

}