Why batch operations reduce round trips in Rest API - See It in Action

Why Batch Operations Reduce Round Trips

📖 Scenario: Imagine you have a list of tasks to send to a server. Sending each task one by one takes a lot of time because each task needs a separate trip to the server. Batch operations let you send many tasks in one trip, saving time and effort.

🎯 Goal: You will create a simple program that shows how sending tasks one by one takes more trips, and how sending them in a batch reduces the number of trips to the server.

📋 What You'll Learn

Create a list of tasks with exact names

Create a batch size variable

Write code to split tasks into batches

Print the number of batches sent

💡 Why This Matters

🌍 Real World

Batch operations are used in apps and websites to send or receive many items at once, like uploading photos or sending messages.

💼 Career

Understanding batch operations helps in building efficient APIs and services that save time and reduce server load.

1

Create a list of tasks

Create a list called tasks with these exact strings: 'task1', 'task2', 'task3', 'task4', 'task5', 'task6'.

Rest API

# Create the list of tasks
# Your code here

Hint

Use square brackets [] to create a list and separate items with commas.

2

Set the batch size

Create a variable called batch_size and set it to 3.

Rest API

tasks = ['task1', 'task2', 'task3', 'task4', 'task5', 'task6']
# Set the batch size to 3
# Your code here

Hint

Just assign the number 3 to the variable batch_size.

3

Split tasks into batches

Create a list called batches that contains sublists of tasks each with length batch_size. Use a for loop with variable i and list slicing tasks[i:i+batch_size].

Rest API

tasks = ['task1', 'task2', 'task3', 'task4', 'task5', 'task6']
batch_size = 3
# Create batches by slicing tasks in steps of batch_size
# Your code here

Hint

Use a list comprehension with range stepping by batch_size and slice the list.

4

Print the number of batches sent

Print the text "Number of batches sent:" followed by the length of batches using print().

Rest API

tasks = ['task1', 'task2', 'task3', 'task4', 'task5', 'task6']
batch_size = 3
batches = [tasks[i:i+batch_size] for i in range(0, len(tasks), batch_size)]
# Print the number of batches
# Your code here

Hint

Use print("Number of batches sent:", len(batches)) to show the result.

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