WebRequestクラスを使ってStringをPostするコード

使用するEncodingはUTF-8を仮定しています。

public static void PostData(string host, int port, string data)
{
    try
    {
        Uri requestUri = new Uri(string.Format("http://{0}:{1}/", host, port));
        WebRequest request = WebRequest.Create(requestUri);
        request.Proxy = new WebProxy();
        request.Method = "POST";
        byte[] postDataBytes = Encoding.UTF8.GetBytes(data);
        request.ContentLength = postDataBytes.Length;

        using (Stream stream = request.GetRequestStream())
        {
            stream.Write(postDataBytes, 0, postDataBytes.Length);
            WebResponse response = request.GetResponse();
            using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8))
            {
                string strResp = reader.ReadToEnd();
                // Do something...
            }
        }
    }
    catch (Exception ex)
    {
        log.ErrorFormat("Error in {0} method\n{1}", MethodBase.GetCurrentMethod().Name, ex.ToString());
    }

}