WCF REST Service to receive gzip(.gz) file

[OperationContract]
       [WebInvoke(Method = "POST", UriTemplate = "processfile",
           RequestFormat = WebMessageFormat.Json,
              ResponseFormat = WebMessageFormat.Xml,
              BodyStyle = WebMessageBodyStyle.Bare)]

       string processfile(Stream input);

public string processfile(Stream input)
        {

            string saveToLog1 = @"E:\TestFiles\LogFilett.txt";
           
            compress(input);

            byte[] input1 = ReadFully(input);
            string output1 = Encoding.UTF8.GetString(input1, 0, input1.Length);
            File.WriteAllText(saveToLog1, output1);
            string saveToLog = @"E:\TestFiles\LogFile.txt";
                      File.AppendAllText(saveToLog, "File received at: " + System.DateTime.Now.ToString().Replace(":", "_").Replace("/", "-").Replace(" ", "_"));
             string saveTo = @"E:\TestFiles\Testtest.gz";
            File.WriteAllText(saveTo, output1, UTF8Encoding.UTF8);

            return string.Format("The input string is: {0}", DateTime.Now.ToString());

        }

public static byte[] ReadFully(Stream input)
       {
           byte[] buffer = new byte[16 * 1024];
           using (MemoryStream ms = new MemoryStream())
           {
               int read;
               while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
               {
                   ms.Write(buffer, 0, read);
               }
               return ms.ToArray();
           }
       }