ASP.NET - blob excel

function from_file_funcion(dir in varchar2, file in varchar2) return blob is

    ret blob;

  begin

    dbms_lob.createTemporary(ret, true);

     from_file(dir, file, ret);

    return ret;

  end from_file_funcion;

  procedure from_file(dir in varchar2, file in varchar2, b in out blob) is

    input_file    utl_file.file_type;

    chunk_size    constant pls_integer := 4096;

    buf           raw                    (4096); -- Must be equal to chunk_size

    read_sofar    pls_integer := 0;              --(avoid PLS-00491: numeric literal required)

    bytes_to_read pls_integer;

  begin

    input_file := utl_file.fopen(dir, file, 'RB');

    begin loop

      utl_file.get_raw(input_file, buf, chunk_size);

      bytes_to_read := length(buf) / 2; -- strange and unexplanable!

      dbms_lob.write(b, bytes_to_read, read_sofar+1, buf);

      read_sofar := read_sofar + bytes_to_read;

    -- utl_file raises no_data_found when unable to read

    end loop; exception when no_data_found then null; end;

    utl_file.fclose(input_file);

  end from_file;

  procedure devuelve_funcion(dir in varchar2, file in varchar2, b in out blob)

  is

  begin

      b:= blob_wrapper.from_file_funcion('CSV_DIR','deve.csv');  

  end;

OracleConnection conn = new OracleConnection("Data Source=bd; User Id=usr;Password=dir;");

                OracleCommand cmd = new OracleCommand();

                cmd.Connection = conn;

                cmd.CommandText = "blob_wrapper.devuelve_funcion";

                cmd.CommandType = CommandType.StoredProcedure;

                OracleParameter directorio = new OracleParameter("dir", OracleType.VarChar, 500);

                directorio.Direction = ParameterDirection.Input;

                directorio.Value = "CSV_DIR";

                cmd.Parameters.Add(directorio);

                OracleParameter file = new OracleParameter("file", OracleType.VarChar, 500);

                file.Direction = ParameterDirection.Input;

                file.Value = "dev.csv";

                cmd.Parameters.Add(file);

                OracleParameter inval = new OracleParameter("b", OracleType.Blob);

                inval.Direction = ParameterDirection.Input;

                inval.Value = null;

                cmd.Parameters.Add(inval);

                OracleParameter outval = new OracleParameter("b", OracleType.Blob);

                outval.Direction = ParameterDirection.Output;

                cmd.Parameters.Add(outval);

                conn.Open();

                cmd.ExecuteNonQuery();

                conn.Close();