WebApiClient.cs

    public class WebApiClient
    {
        private HttpWebRequest httpWebRequest;

        public WebApiClient(Uri uri, int timeOut)
        {
            httpWebRequest = CreateHttpWebRequest(uri, timeOut);
        }

        public string Post(string conteudo)
        {
            byte[] bytes = Encoding.UTF8.GetBytes(conteudo);
            httpWebRequest.ContentLength = bytes.Length;
            httpWebRequest.Method = "POST";
            RunRequest(bytes);
            return GetAnswer();
        }

        private HttpWebRequest CreateHttpWebRequest(Uri uri, int timeOut)
        {
            httpWebRequest = (HttpWebRequest)WebRequest.Create(uri);

            httpWebRequest.ContentType = "text/plain; charset=UTF-8";
            httpWebRequest.KeepAlive = false;
            httpWebRequest.Timeout = timeOut * 1000;
            httpWebRequest.ServicePoint.Expect100Continue = false;
            return httpWebRequest;
        }


        private void RunRequest(byte[] content)
        {
            using (var stream = httpWebRequest.GetRequestStream())
            {
                stream.Write(content, 0, content.Length);
            }
        }

        private string GetAnswer()
        {
            using (var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse())
            {
                using (var responseStream = httpResponse.GetResponseStream())
                {
                    if (responseStream == null)
                        throw new NullReferenceException("responseStream");

                    using (var streamReader = new StreamReader(responseStream))
                    {
                        return streamReader.ReadToEnd();
                    }
                }
            }
        }
    }