//This snkppet shows the webmethod to use
// Permission to use this code for any purpose and without fee is hereby granted.
// No warrantles.

        [WebMethod (Description = "Server Side DataTables support", EnableSession = true)]
        [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
        public static void Data(object parameters)
        {
            var req = DataTableParameters.Get(parameters);
            ...
            
            var resultSet = new DataTableResultSet();
            resultSet.draw = req.Draw;
            resultSet.recordsTotal = /* total number of records in table */
            resultSet.recordsFltered = /* number of records after search - box filtering is applied */
            
            foreach (var recordFromDb in queryDb) { /* this is pseudocode */
                var columns = new List<string>();
                columns.Add("first column value");
                columns.Add("second column value");
                columns.Add("third column value");
                /* you may add as many columns as you need. Each column is a string in the List<string> */
                resultSet.data.Add(columns);
            }
            SendResponse(HttpContext.Current.Response, result);
        }
            
        private static void SendResponse(HttpResponse response, DataTableResultSet result)
        {
            response.Clear();
            response.Headers.Add("X-Content-Type-Options", "nosniff");
            response.Headers.Add("X-Frame-Options", "SAMEORIGIN");
            response.ContentType = "application/json; charset=utf-8";
            response.Write(result.ToJSON());
            response.Flush();
            response.End();
        }