Why delivery guarantees affect correctness in Kafka - See It in Action

Why Delivery Guarantees Affect Correctness in Kafka

📖 Scenario: You are building a simple message processing system using Kafka. Messages represent orders that must be processed exactly once to avoid errors like double billing or lost orders.

🎯 Goal: Learn how different Kafka delivery guarantees (at-most-once, at-least-once, exactly-once) affect the correctness of message processing.

📋 What You'll Learn

Create a Kafka producer with a list of order messages

Set a delivery guarantee configuration variable

Simulate message sending with the chosen delivery guarantee

Print the final processed orders to observe correctness

💡 Why This Matters

🌍 Real World

Kafka is used in real systems to send messages like orders, logs, or events. Delivery guarantees help ensure these messages are processed correctly without loss or duplication.

💼 Career

Understanding delivery guarantees is important for software engineers working with distributed systems, data pipelines, and event-driven architectures to build reliable applications.

1

Create a list of order messages

Create a list called orders with these exact string values: 'order1', 'order2', 'order3'

Kafka

# Create the list of orders
# Your code here

Need a hint?

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

2

Set the delivery guarantee configuration

Create a variable called delivery_guarantee and set it to the string 'at-least-once'

Kafka

orders = ['order1', 'order2', 'order3']
# Set the delivery guarantee to 'at-least-once'
# Your code here

Need a hint?

Assign the string 'at-least-once' to the variable delivery_guarantee.

3

Simulate sending orders with delivery guarantee

Create an empty list called processed_orders. Use a for loop with variable order to iterate over orders. Inside the loop, append order to processed_orders. If delivery_guarantee is 'at-least-once', append order a second time to simulate possible duplicates.

Kafka

orders = ['order1', 'order2', 'order3']
delivery_guarantee = 'at-least-once'
# Simulate sending orders with delivery guarantee
# Your code here

Need a hint?

Use a for loop to add each order to processed_orders. Add it twice if delivery_guarantee is 'at-least-once'.

4

Print the processed orders

Write a print statement to display the processed_orders list.

Kafka

orders = ['order1', 'order2', 'order3']
delivery_guarantee = 'at-least-once'
processed_orders = []
for order in orders:
    processed_orders.append(order)
    if delivery_guarantee == 'at-least-once':
        processed_orders.append(order)
# Print the processed orders
# Your code here

Need a hint?

Use print(processed_orders) to show the list.