Deprecation communication in Rest API - Step-by-Step Execution

Concept Flow - Deprecation communication

Start API Request

↓

Check API Version

↓

Is Version Deprecated?

No→Process Request Normally

Yes↓

Add Deprecation Warning Header

↓

Process Request with Warning

↓

Send Response with Deprecation Info

When an API request is received, the server checks if the API version is deprecated. If yes, it adds a warning header before sending the response.

Execution Sample

Rest API

GET /api/v1/resource HTTP/1.1
Host: example.com

Response:
HTTP/1.1 200 OK
Warning: 299 - "Deprecated API version v1, please upgrade to v2"

This example shows a client requesting a deprecated API version and the server responding with a deprecation warning header.

Execution Table

Step	Action	API Version Checked	Is Deprecated?	Response Header Added	Response Sent
1	Receive API request	v1	Yes	No	No
2	Check version against deprecated list	v1	Yes	No	No
3	Add deprecation warning header	v1	Yes	Yes	No
4	Process request with warning	v1	Yes	Yes	No
5	Send response with warning header	v1	Yes	Yes	Yes
6	End	-	-	-	-

💡 Response sent with deprecation warning because API version v1 is deprecated.

Variable Tracker

Variable	Start	After Step 1	After Step 3	After Step 5	Final
api_version	undefined	v1	v1	v1	v1
deprecated_flag	false	true	true	true	true
warning_header	absent	absent	present	present	present
response_sent	false	false	false	true	true

Key Moments - 2 Insights

Why do we add a warning header instead of blocking the request?

The warning header informs clients about deprecation while still allowing the request to succeed, as shown in steps 3 and 5 of the execution_table.

What happens if the API version is not deprecated?

If the version is not deprecated, the server processes the request normally without adding a warning header, as indicated by the 'No' branch in the concept_flow.

Visual Quiz - 3 Questions

Look at the execution_table, at which step is the deprecation warning header added?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Check the 'Response Header Added' column in the execution_table.

According to variable_tracker, what is the value of 'deprecated_flag' after Step 1?

A true

B false

C undefined

D null

💡 Hint

Look at the 'deprecated_flag' row and the 'After Step 1' column.

If the API version was not deprecated, how would the 'warning_header' variable change in variable_tracker?

A It would be 'present' after Step 3

B It would be 'present' only after Step 5

C It would remain 'absent' throughout

D It would be 'undefined' at start

💡 Hint

Refer to the explanation in key_moments about non-deprecated versions.

Concept Snapshot

Deprecation communication in REST APIs:
- Check API version on each request
- If deprecated, add a Warning header
- Allow request to succeed with warning
- Encourage clients to upgrade
- Helps smooth transition without breaking clients

Full Transcript

When a REST API receives a request, it first checks the API version used. If the version is deprecated, the server adds a warning header to the response to inform the client. The request is still processed normally, but the client is notified to upgrade. This approach avoids breaking existing clients while encouraging migration to newer versions. The execution flow starts with receiving the request, checking the version, adding the warning if needed, processing the request, and finally sending the response with the deprecation information.