module.exports = (app) => {
    app.once('server', (server) => {
      // websocket
    });
    app.on('error', (err, ctx) => {
        // report error
    });
    app.on('request', (ctx) => {
        // log receive request
    });
    app.on('response', (ctx) => {
      // ctx.starttime is set by framework
        // log total cost
    });
  };