Microservice communication basics in Express - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a basic Express server that listens on port 3000.

Express

const express = require('express');
const app = express();

app.get('/', (req, res) => {
  res.send('Hello from service!');
});

app.listen([1], () => {
  console.log('Server is running');
});

Drag options to blanks, or click blank then click option'

A5000

B8080

C3000

D80

Attempts:

3 left

💡 Hint

Common Mistakes

Using port 80 without admin rights

Using a port already in use

The standard port for local Express servers is often 3000. This code starts the server on port 3000.

2fill in blank

medium

Complete the code to send a GET request from one microservice to another using the 'fetch' API.

Express

const fetch = require('node-fetch');

async function getData() {
  const response = await fetch('[1]');
  const data = await response.json();
  return data;
}

Drag options to blanks, or click blank then click option'

A'http://localhost:3000/api/data'

B'file://localhost:3000/api/data'

C'ftp://localhost:3000/api/data'

D'localhost:3000/api/data'

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting the protocol

Using wrong protocols like ftp or file

The fetch URL must start with http:// or https:// for HTTP requests. 'http://localhost:3000/api/data' is correct.

3fill in blank

hard

Fix the error in the Express route to correctly parse JSON request bodies.

Express

const express = require('express');
const app = express();

app.use([1]);

app.post('/data', (req, res) => {
  res.json({ received: req.body });
});

Drag options to blanks, or click blank then click option'

Aexpress.text()

Bexpress.urlencoded()

Cexpress.raw()

Dexpress.json()

Attempts:

3 left

💡 Hint

Common Mistakes

Using express.urlencoded() for JSON

Not using any body parser

To parse JSON bodies in Express, you must use express.json() middleware.

4fill in blank

hard

Fill both blanks to create an Express route that calls another microservice and returns its data.

Express

const fetch = require('node-fetch');
const express = require('express');
const app = express();

app.get('/proxy', async (req, res) => {
  const response = await fetch([1]);
  const data = await response.[2]();
  res.json(data);
});

Drag options to blanks, or click blank then click option'

A'http://localhost:4000/data'

B'http://localhost:4000/info'

Cjson

Dtext

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong URL

Using response.text() when expecting JSON

The fetch URL should point to the other service's endpoint. The response should be parsed as JSON using response.json().

5fill in blank

hard

Fill all three blanks to implement a retry mechanism when calling another microservice.

Express

const fetch = require('node-fetch');

async function fetchWithRetry(url, retries = [1]) {
  for (let i = 0; i < retries; i++) {
    try {
      const response = await fetch(url);
      if (response.ok) {
        return await response.[2]();
      }
    } catch (error) {
      if (i === retries - 1) throw error;
    }
  }
}

const maxRetries = [3];

Drag options to blanks, or click blank then click option'

A3

Bjson

C5

Dtext

Attempts:

3 left

💡 Hint

Common Mistakes

Parsing response as text

Setting retries too low or too high without reason

Retries are set to 3 by default. The response is parsed as JSON. The maxRetries constant is set to 5 for flexibility.