Node

const tracing = require('@opencensus/nodejs');
const zpages = require('@opencensus/exporter-zpages');

const options = {
  port: 8080,   // default
  startServer: true,  // default
  spanNames: ['predefined/span1', 'predefined/span2']
};

const exporter = new zpages.ZpagesExporter(options);
const tracer = tracing.registerExporter(exporter).start().tracer;

const tracing = require('@opencensus/nodejs');
const zpages = require('@opencensus/exporter-zpages');
const stdin = process.openStdin();

const options = {
  port: 8080,   // default
  startServer: true,  // default
  spanNames: ['predefined/span1', 'predefined/span2']
};

const defaultConfig = {
  name: 'readEvaulateProcessLine',
  samplingRate: 1.0  // always sample
};

function delay() {
  for (let i = 0; i < 1000000; i++) {}
}

const exporter = new zpages.ZpagesExporter(options);
const tracer = tracing.registerExporter(exporter).start().tracer;

function readEvaluateProcessLine(input) {
  tracer.startRootSpan(defaultConfig, rootSpan => {
    const text = readLine(input);
    const upperCase = processLine(text);

    process.stdout.write('< ' + upperCase + '\n> ');

    rootSpan.end();
  });
}

function readLine(input) {
  const span = tracer.startChildSpan('readLine');
  span.start();

  const text = input.toString().trim();
  span.addAttribute('length', text.length);
  span.addAttribute('text', text);

  delay();

  span.end();
  return text;
}

function processLine(text) {
  const span = tracer.startChildSpan('processLine');
  span.start();

  const upperCaseText = text.toUpperCase();

  delay();

  span.end();
  return upperCaseText;
}

/*
 * In a REPL:
 * 1. Read input
 * 2. process input
 */
stdin.addListener("data", readEvaluateProcessLine);
process.stdout.write('> ');