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Stream.on()

Set up handler functions for various events on the gRPC stream.

ParameterTypeDescription
eventstringThe event name to define a handler for.
handlerEventHandlerThe function to call when the event happens.

Possible events:

Event nameDescription
dataEmitted when the server sends data.
errorEmitted when an error occurs. In case of the error, an Error object sends to the handler function.
endEmitted when the server closes the incoming stream.

Note

When you enable the experimental async-metric-context feature flag, each Stream.on() handler captures the tags and metadata active when you register it. Metrics emitted by the handler use a copy of that context, and k6 restores the interrupted context after the handler returns or throws. Promise reactions and await continuations created by the handler keep its context.

Example

JavaScript 
import { Client, Stream } from 'k6/net/grpc';
import { sleep } from 'k6';

const client = new Client();
client.load([], '../../grpc_server/route_guide.proto');

export default () => {
  if (__ITER == 0) {
    client.connect('127.0.0.1:10000', { plaintext: true });
  }

  const stream = new Stream(client, 'main.RouteGuide/RecordRoute');

  // sets up a handler for the data (server sends data) event
  stream.on('data', (stats) => {
    console.log('Finished trip with', stats.pointCount, 'points');
    console.log('Passed', stats.featureCount, 'features');
    console.log('Traveled', stats.distance, 'meters');
    console.log('It took', stats.elapsedTime, 'seconds');
  });

  // sets up a handler for the end event (stream closes)
  stream.on('end', function () {
    // The server has finished sending
    client.close();
    console.log('All done');
  });

  // sets up a handler for the error event (an error occurs)
  stream.on('error', function (e) {
    // An error has occurred and the stream has been closed.
    console.log('Error: ' + JSON.stringify(e));
  });

  sleep(1);
};