Stream

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Stream

Using a gRPC client creates a stream. The client should be connected to the server (client.connect called) before creating a stream.

Class/MethodDescription
Stream(client, url, [,params])Using a connected gRPC client and the method’s URL creates a stream. Optionally, you can pass params for additional configuration options like tags, metadata, etc.
Stream.write(message)Writes a message to the stream.
Stream.on(event, handler)Sets up handler functions for various events on the gRPC stream.
Stream.end()Signals to the server that the client has finished sending.
EventHandlerThe handler function for various events on the gRPC stream.
MetadataThe metadata of a gRPC stream’s message.

Examples

A k6 script that sends several randomly chosen points from the pre-generated feature database with a variable delay in between. Prints the statistics when they are sent from the server.

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

const COORD_FACTOR = 1e7;

const GRPC_ADDR = __ENV.GRPC_ADDR || '127.0.0.1:10000';
const GRPC_PROTO_PATH = __ENV.GRPC_PROTO_PATH || '../../grpc_server/route_guide.proto';

const client = new Client();
client.load([], GRPC_PROTO_PATH);

// a sample DB of points
const DB = [
  {
    location: { latitude: 407838351, longitude: -746143763 },
    name: 'Patriots Path, Mendham, NJ 07945, USA',
  },
  {
    location: { latitude: 408122808, longitude: -743999179 },
    name: '101 New Jersey 10, Whippany, NJ 07981, USA',
  },
  {
    location: { latitude: 413628156, longitude: -749015468 },
    name: 'U.S. 6, Shohola, PA 18458, USA',
  },
  {
    location: { latitude: 419999544, longitude: -740371136 },
    name: '5 Conners Road, Kingston, NY 12401, USA',
  },
  {
    location: { latitude: 414008389, longitude: -743951297 },
    name: 'Mid Hudson Psychiatric Center, New Hampton, NY 10958, USA',
  },
  {
    location: { latitude: 419611318, longitude: -746524769 },
    name: '287 Flugertown Road, Livingston Manor, NY 12758, USA',
  },
  {
    location: { latitude: 406109563, longitude: -742186778 },
    name: '4001 Tremley Point Road, Linden, NJ 07036, USA',
  },
  {
    location: { latitude: 416802456, longitude: -742370183 },
    name: '352 South Mountain Road, Wallkill, NY 12589, USA',
  },
  {
    location: { latitude: 412950425, longitude: -741077389 },
    name: 'Bailey Turn Road, Harriman, NY 10926, USA',
  },
  {
    location: { latitude: 412144655, longitude: -743949739 },
    name: '193-199 Wawayanda Road, Hewitt, NJ 07421, USA',
  },
];

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

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

  stream.on('data', (stats) => {
    console.log('Finished trip with', stats.pointCount, 'points');
    console.log('Passed', stats.featureCount, 'features');
    console.log('Travelled', stats.distance, 'meters');
    console.log('It took', stats.elapsedTime, 'seconds');
  });

  stream.on('error', (err) => {
    console.log('Stream Error: ' + JSON.stringify(err));
  });

  stream.on('end', () => {
    client.close();
    console.log('All done');
  });

  // send 5 random items
  for (let i = 0; i < 5; i++) {
    const point = DB[Math.floor(Math.random() * DB.length)];
    pointSender(stream, point);
  }

  // close the client stream
  stream.end();

  sleep(1);
};

const pointSender = (stream, point) => {
  console.log(
    'Visiting point ' +
      point.name +
      ' ' +
      point.location.latitude / COORD_FACTOR +
      ', ' +
      point.location.longitude / COORD_FACTOR
  );

  // send the location to the server
  stream.write(point.location);

  sleep(0.5);
};

A k6 script that sends a rectangle message and results (features) are streamed back to the client.

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

const COORD_FACTOR = 1e7;

const GRPC_ADDR = __ENV.GRPC_ADDR || '127.0.0.1:10000';
const GRPC_PROTO_PATH = __ENV.GRPC_PROTO_PATH || '../../grpc_server/route_guide.proto';

const client = new Client();

client.load([], GRPC_PROTO_PATH);

export default () => {
  client.connect(GRPC_ADDR, { plaintext: true });

  const stream = new Stream(client, 'main.FeatureExplorer/ListFeatures', null);

  stream.on('data', function (feature) {
    console.log(
      'Found feature called "' +
        feature.name +
        '" at ' +
        feature.location.latitude / COORD_FACTOR +
        ', ' +
        feature.location.longitude / COORD_FACTOR
    );
  });

  stream.on('end', function () {
    // The server has finished sending
    client.close();
    console.log('All done');
  });

  stream.on('error', function (e) {
    // An error has occurred and the stream has been closed.
    console.log('Error: ' + JSON.stringify(e));
  });

  // send a message to the server
  stream.write({
    lo: {
      latitude: 400000000,
      longitude: -750000000,
    },
    hi: {
      latitude: 420000000,
      longitude: -730000000,
    },
  });

  sleep(0.5);
};

The preceding examples use a demo server, which you can run with the following command (Golang should be installed) in k6 repository’s root:

bash 
go run -mod=mod examples/grpc_server/*.go