问如何在feathersjs websocket api中响应纯文本？

EN

class Monitor {

  find(_) {
    const metrics = prom.register.metrics();
    log.info(metrics);
    return new Promise((resolve) => {
      resolve({text: metrics});
    });
  }
}

function restFormatter(req, res) {
  res.format({
    'text/plain': function() {
      log('xxxx:', res);
      res.end(`The Message is: "${res.data}"`);
    }
  });
}

module.exports = function () {
  const app = this;

  // Initialize our service with any options it requires
  const service = new Monitor();
  app.configure(rest(restFormatter)).use('/metrics', service);

  // Get our initialize service to that we can bind hooks
  const monitorService = app.service('/metrics');

  // Set up our before hooks
  monitorService.before(hooks.before);

  // Set up our after hooks
  monitorService.after(hooks.after);
  return service;
};

module.exports.Monitor = Monitor;

"# HELP nodejs_gc_runs_total Count of total garbage collections.\n# TYPE nodejs_gc_runs_total counter\n\n# HELP nodejs_gc_pause_seconds_total Time spent in GC Pause in seconds.\n# TYPE nodejs_gc_pause_seconds_total counter\n\n# HELP nodejs_gc_reclaimed_bytes_total Total number of bytes reclaimed by GC.\n# TYPE nodejs_gc_reclaimed_bytes_total counter\n"

# HELP nodejs_gc_runs_total Count of total garbage collections.
# TYPE nodejs_gc_runs_total counter

# HELP nodejs_gc_pause_seconds_total Time spent in GC Pause in seconds.
# TYPE nodejs_gc_pause_seconds_total counter

# HELP nodejs_gc_reclaimed_bytes_total Total number of bytes reclaimed by GC.
# TYPE nodejs_gc_reclaimed_bytes_total counter

# HELP newConnection The number of requests served
# TYPE newConnection counter

app
  .use(compress())
  .options('*', cors())
  .use(cors())
  .use('/', serveStatic(app.get('public')))
  .use(bodyParser.json())
  .use(bodyParser.urlencoded({extended: true}))
  .configure(hooks())
  .configure(rest())
  .configure(
    swagger({
      docsPath: '/docs',
      uiIndex: path.join(__dirname, '../public/docs.html'),
      info: {
        title: process.env.npm_package_fullName,
        description: process.env.npm_package_description
      }
    })
  )
  .configure(
    primus(
      {
        transformer: 'websockets',
        timeout: false
      },
      (primus) => {
        primus.library();
        primus.save(path.join(__dirname, '../public/dist/primus.js'));
      }
    )
  )
  .configure(services)
  .configure(middleware);