Statelessness requirement in Rest API - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a stateless header to the HTTP response.

Rest API

response.headers['[1]'] = 'no-store'

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

AAuthorization

BUser-Agent

CContent-Type

DCache-Control

Attempts:

3 left

💡 Hint

Common Mistakes

Using Authorization header instead of Cache-Control

Forgetting to set any header for statelessness

The Cache-Control header with value no-store ensures responses are not cached, supporting statelessness.

2fill in blank

medium

Complete the code to extract the client state from the request in a stateless API.

Rest API

client_state = request.headers.get('[1]')

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

ACookie

BHost

CAuthorization

DContent-Length

Attempts:

3 left

💡 Hint

Common Mistakes

Using Cookie header which implies server-side session

Using Content-Length which is unrelated to client state

In stateless APIs, client state is often passed in the Authorization header, such as tokens.

3fill in blank

hard

Fix the error in the code to ensure the API remains stateless by avoiding server-side session storage.

Rest API

session['user'] = [1]

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

Arequest.headers.get('Authorization')

Brequest.cookies.get('session_id')

Cdatabase.query_user()

Dcache.get('user')

Attempts:

3 left

💡 Hint

Common Mistakes

Storing user info in session or cache breaks statelessness

Using cookies implies server-side session

Using the Authorization header avoids server-side session storage, keeping the API stateless.

4fill in blank

hard

Fill both blanks to create a stateless API endpoint that reads client token and returns a response without server session.

Rest API

def get_data(request):
    token = request.headers.get('[1]')
    data = fetch_data(token)
    return [2](data)

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

AAuthorization

Bjsonify

Crender_template

DCookie

Attempts:

3 left

💡 Hint

Common Mistakes

Using Cookie header which implies server session

Using render_template which may rely on server state

The Authorization header carries the client token, and jsonify returns JSON without server session.

5fill in blank

hard

Fill all three blanks to implement a stateless POST endpoint that validates a token, processes data, and returns JSON response.

Rest API

def post_data(request):
    token = request.headers.get('[1]')
    if not validate_[2](token):
        return [3]({'error': 'Unauthorized'}, 401)
    result = process(request.json)
    return jsonify(result)

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

AAuthorization

Btoken

Cmake_response

DCookie

Attempts:

3 left

💡 Hint

Common Mistakes

Using Cookie header breaks statelessness

Returning raw dict without response wrapper may cause issues

The Authorization header carries the token, validate_token checks it, and make_response creates the HTTP response without server session.

Practice

1. What does the statelessness requirement in REST APIs mean?

easy

A. Each request from client to server must contain all information needed to understand and process it.

B. The server must remember all previous requests from the client.

C. The server stores user session data between requests.

D. The client does not need to send any authentication information after the first request.

Solution

1. Step 1: Understand statelessness in REST

   Statelessness means the server does not keep any client context between requests.

2. Step 2: Identify what each request must contain

   Each request must have all data needed to process it, including authentication and parameters.

3. Final Answer:

   Each request from client to server must contain all information needed to understand and process it. -> Option A

4. Quick Check:

   Statelessness = All info in each request [OK]

Hint: Remember: server forgets past requests, all info sent every time [OK]

Common Mistakes:

• Thinking server stores session data
• Assuming client sends partial info only once
• Confusing statelessness with authentication persistence

2. Which of the following HTTP request examples follows the statelessness principle?

easy

A. POST /login HTTP/1.1\nHost: example.com\nCookie: sessionid=abc123

B. GET /profile HTTP/1.1\nHost: example.com

C. GET /profile HTTP/1.1\nHost: example.com\nReferer: /home

D. GET /profile HTTP/1.1\nHost: example.com\nAuthorization: Bearer token123

Solution

1. Step 1: Check if request contains all needed info

   GET /profile HTTP/1.1\nHost: example.com\nAuthorization: Bearer token123 includes Authorization header, so server can authenticate without stored session.

2. Step 2: Compare with other options

   POST /login HTTP/1.1\nHost: example.com\nCookie: sessionid=abc123 relies on cookies, which imply server state. Options B and D lack explicit authentication info.

3. Final Answer:

   GET request with Authorization header carrying token -> Option D

4. Quick Check:

   Auth info in request = stateless [OK]

Hint: Look for Authorization header in request to confirm statelessness [OK]

Common Mistakes:

• Assuming cookies mean statelessness
• Ignoring missing auth info in requests
• Confusing Referer header with authentication

3. Consider this REST API server behavior: It does not store any client session data. A client sends two requests:
1. GET /data?user=123&token=abc
2. GET /data?user=123
What will happen on the second request?

medium

A. The server rejects the request due to missing authentication token.

B. The server processes the request successfully using stored session data.

C. The server processes the request ignoring authentication.

D. The server crashes because of missing parameters.

Solution

1. Step 1: Analyze statelessness and authentication

   Since server is stateless, it does not remember previous tokens; each request must include token.

2. Step 2: Check second request parameters

   Second request lacks token parameter, so server cannot authenticate and must reject it.

3. Final Answer:

   Server rejects request due to missing authentication token. -> Option A

4. Quick Check:

   Missing token means reject request [OK]

Hint: Every request needs auth info; missing it causes rejection [OK]

Common Mistakes:

• Assuming server remembers token from first request
• Thinking server ignores missing token
• Believing server crashes on missing params

4. A developer wrote this REST API code snippet to handle user requests:

def handle_request(request):
    if 'session_id' in server_memory:
        user = server_memory['session_id']
        return f"Hello, {user}!"
    else:
        return "Unauthorized"

What is the main problem related to statelessness here?

medium

A. The code does not check for authentication token in the request.

B. The code correctly implements statelessness by using server memory.

C. The code stores session data on the server, violating statelessness.

D. The code uses request parameters properly for authentication.

Solution

1. Step 1: Identify server memory usage

   The code checks 'session_id' in server_memory, meaning it stores client state on server.

2. Step 2: Compare with statelessness principle

   Statelessness forbids server from storing client session data between requests.

3. Final Answer:

   Code stores session data on server, violating statelessness. -> Option C

4. Quick Check:

   Server storing session = stateful, not stateless [OK]

Hint: Stateless means no server memory of client sessions [OK]

Common Mistakes:

• Thinking server memory use is allowed
• Ignoring missing token checks
• Assuming code is stateless because it returns a string

5. You are designing a REST API for a shopping cart. To keep it stateless, which approach is best to track the user's cart items across requests?

hard

A. Store the cart items in a server-side session linked to the user ID.

B. Require the client to send the full cart data with each request.

C. Save the cart data in a database and keep session ID on server memory.

D. Use cookies to store cart items and rely on server to read them.

Solution

1. Step 1: Understand statelessness in API design

   Statelessness means server does not keep client state; all info must come with each request.

2. Step 2: Evaluate options for cart tracking

   Require the client to send the full cart data with each request. requires the client to send the full cart data with each request, fitting statelessness. Options A, B, and C rely on server or cookies storing state.

3. Final Answer:

   Require client to send full cart data with each request. -> Option B

4. Quick Check:

   Client sends all data = stateless API [OK]

Hint: Keep server stateless by sending all data from client every time [OK]

Common Mistakes:

• Using server sessions to store cart
• Assuming cookies make API stateless
• Relying on server memory for user data