code: function prepareData(items, with_timestamps, with_ns) {
      var data = {
          request: 'sender data',
          data: items
      };
  
      if (with_timestamps) {
          var ts = Date.now() / 1000;
          data.clock = ts | 0;
  
          if (with_ns) {
              data.ns = (ts % 1) * 1000 * 1000000 | 0;
          }
      }
  
      var payload = new Buffer(JSON.stringify(data), 'utf8'),
          header  = new Buffer(5 + 4); // ZBXD\1 + packed payload.length
  
      header.write('ZBXD\x01');
      header.writeInt32LE(payload.length, 5);
      return Buffer.concat([header, new Buffer('\x00\x00\x00\x00'), payload]);
  }
docs: takes items array and prepares payload for sending