event store sample

index.js

const Buffer = require('buffer').Buffer;
const uuid = require('uuid/v4');
const eventstore = require('eventstore-node');

const eventstoreUrl = process.env.EVENTSTORE_URL || 'tcp://localhost:1113';
const connSettings = {};
const esConnection = eventstore.createConnection(connSettings, eventstoreUrl);
esConnection.connect();
esConnection.once('connected', endpoint => {
  console.log(`Connected to eventstore at ${endpoint.host}:${endpoint.port}`);
});

function stream(streamName) {
  return async function sendMessage(message, type) {
    const id = uuid();
    const event = eventstore.createJsonEventData(id, message, null, type);
    process.stdout.write('.');
    try {
      const result = await esConnection.appendToStream(streamName, eventstore.expectedVersion.any, event);
      process.stdout.write(':');
    } catch (exception) {
      console.error(`Error sending ${id}: ${exception}`);
    }
  };
}

const send = stream('hello-world');
const writing = process.env.WRITING === 'true';
if (writing) {
  setInterval(() => {
    send({
      message: 'hello world!',
      value: uuid(),
      created: (new Date()).toISOString(),
    }, 'pulse');
  }, 10);
} else {
  setImmediate(async function resume() {
    try {
      const start = new Date();
      const result = await esConnection
            .readStreamEventsForward('hello-world', 0, 4096);
      const events = result.events.map(e => ({
        id: e.event.eventId,
        number: e.event.eventNumber,
        type: e.event.eventType,
        created: e.created,
        event: JSON.parse(Buffer.from(e.event.data).toString('utf8')),
      }));
      let c = 0;
      events.forEach(() => c++);
      const finish = new Date();
      console.log(`done loading ${c} events in ${finish - start}ms`);
    } catch (exception) {
      console.error(`Error resuming: ${exception}`);
    }
  });
}

console.log('started...');