Message delivery guarantees in HLD - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select the message delivery guarantee that ensures a message is delivered at least once.

HLD

delivery_guarantee = "[1]"

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

Aat-most-once

Bexactly-once

Cat-least-once

Dbest-effort

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'at-most-once' which may lose messages.

Confusing 'exactly-once' with 'at-least-once'.

The at-least-once guarantee ensures that messages are delivered one or more times, preventing loss but possibly causing duplicates.

2fill in blank

medium

Complete the code to select the message delivery guarantee that ensures a message is delivered no more than once.

HLD

delivery_guarantee = "[1]"

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

Abest-effort

Bat-least-once

Cexactly-once

Dat-most-once

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'at-least-once' which allows duplicates.

Confusing 'exactly-once' with 'at-most-once'.

The at-most-once guarantee ensures messages are delivered zero or one time, which may result in message loss but no duplicates.

3fill in blank

hard

Fix the error in the code to select the message delivery guarantee that ensures a message is delivered exactly once.

HLD

delivery_guarantee = "[1]"

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

Aexactly-once

Bbest-effort

Cat-most-once

Dat-least-once

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'at-least-once' which may cause duplicates.

Choosing 'at-most-once' which may lose messages.

The exactly-once guarantee ensures that each message is delivered one and only one time, avoiding duplicates and loss.

4fill in blank

hard

Fill both blanks to complete the message delivery flow that ensures exactly-once delivery using acknowledgments and deduplication.

HLD

if message_received and not [1]:
    process_message()
    send_[2]()

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

Amessage_processed

Bmessage_ack

Cmessage_duplicate

Dmessage_retry

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'message_duplicate' instead of 'message_processed' for the check.

Sending 'message_retry' instead of acknowledgment.

To ensure exactly-once delivery, the system checks if the message was already processed (message_processed) to avoid duplicates, then sends an acknowledgment (message_ack) after processing.

5fill in blank

hard

Fill all three blanks to complete the code snippet that implements at-least-once delivery with retries and acknowledgment.

HLD

while not [1]:
    send_message()
    [2] = wait_for_[3]()

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

Aack_received

Cack

Dmessage

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing 'message' with 'ack' in the wait function.

Using inconsistent variable names for acknowledgment.

The loop continues until an acknowledgment (ack_received) is true. The system waits for an ack message after sending.