Retry and failure handling in Rest API - Step-by-Step Execution

Concept Flow - Retry and failure handling

Start API Request

↓

Send Request

↓

Response Received?

No→Retry Count < Max?

↓

Process Response

v +---> Back to Send Request↓

Success: End

↩v +---> Back to Send Request

This flow shows how an API request is sent, checked for success, retried if it fails, and stops after max retries.

Execution Sample

Rest API

max_retries = 3
retry_count = 0
while retry_count < max_retries:
    response = send_api_request()
    if response == 'success':
        break
    retry_count += 1

This code tries to send an API request up to 3 times until it succeeds.

Execution Table

Attempt	retry_count	send_api_request() result	Condition (success?)	Action
1	0	'fail'	No	retry_count = 1, retry again
2	1	'fail'	No	retry_count = 2, retry again
3	2	'success'	Yes	break loop, success

💡 Loop ends because response was 'success' on attempt 3

Variable Tracker

Variable	Start	After 1	After 2	After 3	Final
retry_count	0	1	2	2	2
response	N/A	'fail'	'fail'	'success'	'success'

Key Moments - 3 Insights

Why does retry_count increase even when the response is 'fail'?

Because each failed attempt increments retry_count to track how many tries have been made, as shown in rows 1 and 2 of the execution_table.

What stops the retry loop from running forever?

The loop stops when retry_count reaches max_retries or when a 'success' response is received, as shown by the break on attempt 3 in the execution_table.

Why do we break the loop when response is 'success'?

Because the goal is to stop retrying once the API call succeeds, which is shown in row 3 where the condition is 'Yes' and the loop breaks.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of retry_count after the second attempt?

A 2

B 1

C 0

D 3

💡 Hint

Check the 'retry_count' column in the execution_table row for Attempt 2.

At which attempt does the API request succeed according to the execution_table?

A Attempt 1

B Attempt 3

C Attempt 2

D Attempt 4

💡 Hint

Look at the 'send_api_request() result' and 'Condition (success?)' columns.

If the API never returns 'success', what will happen to retry_count?

A It will decrease

B It will stay at 0

C It will increase until max_retries

D It will become negative

💡 Hint

Refer to the variable_tracker and the loop condition in the code sample.

Concept Snapshot

Retry and failure handling:
- Send API request
- Check if response is success
- If fail, increase retry count
- Retry until max retries or success
- Stop retrying on success or max attempts

Full Transcript

This visual execution shows how retry and failure handling works in API calls. The program sends a request and checks if it succeeded. If it fails, it increases a retry counter and tries again. This repeats until the request succeeds or the maximum number of retries is reached. The execution table tracks each attempt, the retry count, the response, and the action taken. Key moments clarify why retry_count increases on failure, what stops the loop, and why the loop breaks on success. The quiz tests understanding of retry counts, success attempt, and behavior when success never happens.