API gateway concept in Express - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a basic API gateway route in Express.

Express

app.[1]('/api/service', (req, res) => { res.send('Service response'); });

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

Aget

Blisten

Cuse

Dconnect

Attempts:

3 left

💡 Hint

Common Mistakes

Using app.listen instead of app.get

Using app.use which is for middleware, not route handling

The get method defines a route for HTTP GET requests, which is typical for API gateway endpoints.

2fill in blank

medium

Complete the code to forward the client request to the backend service URL.

Express

const response = await fetch('[1]' + req.url);

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Ahttps://api.example.com

Bhttp://localhost:3000

Cftp://backend.service

Dfile://local/path

Attempts:

3 left

💡 Hint

Common Mistakes

Using FTP or file protocol instead of HTTP/HTTPS

Using localhost which is not scalable for production

The API gateway forwards requests to the backend service URL, which is typically an HTTP(S) endpoint like https://api.example.com.

3fill in blank

hard

Fix the error in the code to correctly proxy the request headers.

Express

const backendResponse = await fetch(backendUrl, { headers: req.[1] });

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Abody

Bparams

Cheaders

Dquery

Attempts:

3 left

💡 Hint

Common Mistakes

Using body instead of headers

Using params or query which are for URL parameters

The headers property contains the HTTP headers from the client request, which should be forwarded to the backend.

4fill in blank

hard

Fill both blanks to correctly send the backend response status and body to the client.

Express

res.status(backendResponse.[1]).[2](await backendResponse.text());

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Astatus

Bsend

Cjson

Dbody

Attempts:

3 left

💡 Hint

Common Mistakes

Using json() when the response is plain text

Using body property instead of status for status code

The status method sets the HTTP status code, and send sends the response body as text.

5fill in blank

hard

Fill all three blanks to implement a simple API gateway middleware that logs requests, forwards them, and sends back the response.

Express

app.use(async (req, res) => {
  console.log('Request to:', [1]);
  const backendResponse = await fetch([2] + req.url, { headers: req.[3] });
  res.status(backendResponse.status).send(await backendResponse.text());
});

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

Areq.url

Bhttps://backend.service

Cheaders

Dreq.body

Attempts:

3 left

💡 Hint

Common Mistakes

Logging req.body instead of req.url

Using incorrect backend URL format

Forwarding body instead of headers

The middleware logs the request URL (req.url), forwards the request to the backend service URL (https://backend.service), and forwards the request headers (headers).