Why batch operations reduce round trips in Rest API - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to send a batch request using the fetch API.

Rest API

fetch('/api/batch', { method: '[1]' })

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

APOST

BGET

CPUT

DDELETE

Attempts:

3 left

💡 Hint

Common Mistakes

Using GET instead of POST for batch requests.

Batch operations usually use POST to send multiple requests in one call.

2fill in blank

medium

Complete the code to create a batch payload with multiple requests.

Rest API

const batchPayload = { requests: [[1]] };

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

A[{ method: 'GET', path: '/users' }]

Bmethod: 'GET', path: '/users'

C{ method: 'GET', path: '/users' }

D'{ method: GET, path: /users }'

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to wrap the request in an object or array.

The requests array contains objects describing each request.

3fill in blank

hard

Fix the error in the code to send batch requests correctly.

Rest API

fetch('/api/batch', { method: 'POST', body: JSON.stringify([1]) })

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

AbatchPayload

Bbatchpayload

CbatchPayload.toString()

DbatchPayload.json()

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong case for variable names.

The variable name is case sensitive and must be exactly 'batchPayload'.

4fill in blank

hard

Fill both blanks to handle the batch response and extract results.

Rest API

fetch('/api/batch', { method: 'POST', body: JSON.stringify(batchPayload) })
  .then(response => response.[1]())
  .then(data => data.[2]);

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

Ajson

Bresults

Ctext

Dbody

Attempts:

3 left

💡 Hint

Common Mistakes

Using response.text() instead of response.json().

Accessing wrong property name.

Use response.json() to parse JSON, then access the 'results' array from the data.

5fill in blank

hard

Fill all three blanks to create a batch request, send it, and log each response status.

Rest API

const batchPayload = { requests: [
  { method: '[1]', path: '/users' },
  { method: '[2]', path: '/posts' }
] };

fetch('/api/batch', { method: 'POST', body: JSON.stringify(batchPayload) })
  .then(res => res.[3]())
  .then(data => {
    data.results.forEach(r => console.log(r.status));
  });

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

AGET

BPOST

Cjson

DPUT

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing HTTP methods incorrectly.

Not parsing response as JSON.

The first request uses GET, the second POST, and the response is parsed as JSON.

Practice

1. Why do batch operations reduce the number of round trips in REST APIs?

easy

A. Because they send requests one by one quickly

B. Because they use a faster internet connection

C. Because they skip server authentication

D. Because they combine multiple requests into a single network call

Solution

1. Step 1: Understand what a round trip means in REST APIs

   A round trip is when your app sends a request to the server and waits for a response.

2. Step 2: Explain how batch operations affect round trips

   Batch operations group many requests into one, so only one round trip is needed instead of many.

3. Final Answer:

   Because they combine multiple requests into a single network call -> Option D

4. Quick Check:

   Batch requests reduce round trips = Because they combine multiple requests into a single network call [OK]

Hint: Batch means group requests to send once [OK]

Common Mistakes:

• Thinking batch speeds internet connection
• Believing batch skips authentication
• Assuming batch sends requests separately

2. Which of the following is the correct way to send a batch request in JSON format?

easy

A. {"requests": [{"method": "GET", "url": "/users"}]}

B. [{"method": "GET", "url": "/users"}]

C. {"request": {"method": "GET", "url": "/users"}}

D. {"methods": ["GET"], "urls": ["/users"]}

Solution

1. Step 1: Identify the standard batch request format

   Batch requests usually wrap multiple requests inside a "requests" array in a JSON object.

2. Step 2: Match the correct JSON structure

   {"requests": [{"method": "GET", "url": "/users"}]} correctly uses {"requests": [...]}, while others miss this structure or use wrong keys.

3. Final Answer:

   {"requests": [{"method": "GET", "url": "/users"}]} -> Option A

4. Quick Check:

   Batch JSON uses "requests" array = {"requests": [{"method": "GET", "url": "/users"}]} [OK]

Hint: Batch JSON wraps requests in a "requests" array [OK]

Common Mistakes:

• Using array without key "requests"
• Using singular "request" instead of plural
• Separating methods and URLs into different arrays

3. Consider this pseudo-code for sending batch requests:

batch = [
  {"method": "GET", "url": "/items/1"},
  {"method": "GET", "url": "/items/2"}
]
response = send_batch(batch)
print(len(response))

What will be the output?

medium

A. 1

B. 2

C. 0

D. Error

Solution

1. Step 1: Understand the batch request content

   The batch contains two GET requests for two different items.

2. Step 2: Analyze the response length

   Each request in the batch returns one response, so the response list length is 2.

3. Final Answer:

   2 -> Option B

4. Quick Check:

   Batch of 2 requests returns 2 responses = 2 [OK]

Hint: Batch response count matches request count [OK]

Common Mistakes:

• Assuming batch returns single combined response
• Expecting zero because of batch
• Thinking batch causes error without reason

4. You wrote this batch request code but it fails:

batch = {
  "requests": {
    "method": "GET",
    "url": "/data"
  }
}
response = send_batch(batch)

What is the main error?

medium

A. The URL should be a full URL, not a path

B. The method should be lowercase "get"

C. The "requests" key should hold a list, not a single object

D. Batch requests cannot use GET method

Solution

1. Step 1: Check the "requests" value type

   Batch requests expect "requests" to be a list of request objects, not a single object.

2. Step 2: Identify the error cause

   Using an object instead of a list causes the batch to fail because it expects multiple requests.

3. Final Answer:

   The "requests" key should hold a list, not a single object -> Option C

4. Quick Check:

   Batch "requests" must be a list = The "requests" key should hold a list, not a single object [OK]

Hint: "requests" must be a list even for one request [OK]

Common Mistakes:

• Using single object instead of list for "requests"
• Changing HTTP method case unnecessarily
• Thinking full URL is always required
• Believing GET is disallowed in batch

5. You want to update 100 user records via a REST API. Which approach best reduces round trips and improves efficiency?

hard

A. Send a single batch request containing all 100 updates

B. Send 100 separate PUT requests, one per user

C. Send one PUT request with only the first user update

D. Send 10 batch requests each with 5 updates

Solution

1. Step 1: Compare sending many requests vs batch

   Sending 100 separate requests causes 100 round trips, which is slow and inefficient.

2. Step 2: Evaluate batch request benefits

   A single batch request with all 100 updates reduces round trips to 1, saving time and network use.

3. Final Answer:

   Send a single batch request containing all 100 updates -> Option A

4. Quick Check:

   One batch request for many updates = Send a single batch request containing all 100 updates [OK]

Hint: One batch request beats many single requests [OK]

Common Mistakes:

• Sending many separate requests wastes round trips
• Sending partial updates misses data
• Splitting into many small batches adds overhead