REST API best practices in HLD - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

HTTP Methods Usage in REST APIs

Which HTTP method is the most appropriate to update a resource partially in a REST API?

A GET

B PATCH

C PUT

D DELETE

💡 Hint

Think about the method that allows partial updates without replacing the entire resource.

PATCH is used for partial updates to a resource, while PUT replaces the entire resource.

❓ Architecture

intermediate

Statelessness in REST APIs

What is the main advantage of designing a REST API to be stateless?

A It enables the server to handle each request independently without client context.

B It allows the server to store client session data for faster responses.

C It requires the client to maintain a persistent connection to the server.

D It forces the server to keep track of user authentication state.

💡 Hint

Consider how statelessness affects scalability and server load.

Statelessness means each request contains all information needed, allowing servers to handle requests independently and scale easily.

❓ scaling

advanced

Handling High Traffic in REST APIs

Which strategy best helps a REST API handle sudden spikes in traffic without degrading performance?

A Use synchronous processing for all requests to maintain order.

B Store all client sessions on the server to reduce repeated authentication.

C Implement rate limiting and caching mechanisms.

D Disable load balancers to reduce network overhead.

💡 Hint

Think about controlling request volume and reducing repeated work.

Rate limiting prevents overload by limiting requests per client, and caching reduces repeated processing, improving performance during spikes.

❓ tradeoff

advanced

Choosing Between JSON and XML for REST APIs

What is a key tradeoff when choosing JSON over XML as the data format for a REST API?

A XML supports namespaces and schema validation, JSON does not.

B JSON is more verbose but easier to parse than XML.

C JSON requires more bandwidth due to its structure.

D XML is less human-readable compared to JSON.

💡 Hint

Consider features related to data validation and complexity.

XML supports namespaces and schema validation, which JSON lacks, but JSON is simpler and lighter for most REST APIs.

❓ estimation

expert

Estimating API Server Capacity

You expect 10,000 requests per minute to your REST API. Each request takes 100ms of server processing time. How many concurrent server threads are needed to handle the load without queuing?

A Approximately 10 threads

B Approximately 100 threads

C Approximately 1,000 threads

D Approximately 17 threads

💡 Hint

Calculate how many requests happen per second and how many can be processed simultaneously.

10,000 requests/min = ~167 requests/sec. Each takes 0.1s, so concurrent threads = 167 * 0.1 = ~17.

Practice

1. Which HTTP method is typically used to update an existing resource in a REST API?

easy

A. PUT

B. GET

C. POST

D. DELETE

Solution

1. Step 1: Understand HTTP methods for REST

   GET retrieves data, POST creates new resources, PUT updates existing resources, DELETE removes resources.

2. Step 2: Identify method for updating

   PUT is the standard method to update or replace an existing resource in REST APIs.

3. Final Answer:

   PUT -> Option A

4. Quick Check:

   Update = PUT [OK]

Hint: Update resource? Think PUT method [OK]

Common Mistakes:

• Confusing POST with update instead of create
• Using GET for updates
• Using DELETE to update

2. Which of the following is the correct way to version a REST API in the URL?

easy

A. /v1/api/resource

B. /api/resource/v1

C. /api/v1/resource

D. /api/resource?version=1

Solution

1. Step 1: Understand common versioning patterns

   Versioning is often done in the URL path to clearly separate API versions.

2. Step 2: Identify correct version placement

   Placing version immediately after the base API path, like /api/v1/resource, is standard practice.

3. Final Answer:

   /api/v1/resource -> Option C

4. Quick Check:

   Version in path = /api/v1/ [OK]

Hint: Version goes right after /api/ in URL path [OK]

Common Mistakes:

• Putting version after resource name
• Using query parameters for versioning
• Placing version before /api/

3. Given the following API response status codes, which one indicates a successful resource creation?

{
  "status": 201,
  "message": "Created"
}

medium

A. 200 OK

B. 201 Created

C. 400 Bad Request

D. 404 Not Found

Solution

1. Step 1: Review HTTP status codes for success

   200 means success for general requests, 201 means resource created successfully.

2. Step 2: Match status code to creation

   201 Created is the correct code to indicate a new resource was successfully created.

3. Final Answer:

   201 Created -> Option B

4. Quick Check:

   Creation success = 201 [OK]

Hint: 201 means resource created successfully [OK]

Common Mistakes:

• Confusing 200 with creation success
• Using 400 or 404 for success
• Ignoring status code meaning

4. A developer designed a REST API endpoint as POST /users/delete to delete a user. What is the best fix to follow REST API best practices?

medium

A. Change to GET /users/delete

B. Keep POST /users/delete but add a query param

C. Use PUT /users/delete

D. Change to DELETE /users/{id}

Solution

1. Step 1: Identify correct HTTP method for deletion

   DELETE method is the standard for removing resources in REST APIs.

2. Step 2: Correct endpoint structure

   Use resource identifier in URL path like /users/{id} with DELETE method for clarity and REST compliance.

3. Final Answer:

   Change to DELETE /users/{id} -> Option D

4. Quick Check:

   Delete resource = DELETE /resource/{id} [OK]

Hint: Use DELETE method with resource ID in URL [OK]

Common Mistakes:

• Using POST for delete actions
• Using GET to delete resources
• Adding delete action in URL path

5. You want to design a REST API that returns a list of products with optional filtering by category and price range. Which approach follows REST API best practices?

hard

A. GET /products?category=electronics&min_price=100&max_price=500

B. POST /products/filter with JSON body containing filters

C. GET /products/filter/category/electronics/price/100-500

D. PUT /products with filter parameters in the body

Solution

1. Step 1: Understand filtering in REST APIs

   Filtering is best done using query parameters in GET requests to keep APIs simple and cacheable.

2. Step 2: Evaluate options for filtering

   GET /products?category=electronics&min_price=100&max_price=500 uses GET with query parameters, which is standard and clear. Other options misuse POST or PUT or complex URL paths.

3. Final Answer:

   GET /products?category=electronics&min_price=100&max_price=500 -> Option A

4. Quick Check:

   Filter with GET query params [OK]

Hint: Use GET with query parameters for filtering [OK]

Common Mistakes:

• Using POST or PUT for filtering
• Embedding filters in URL path segments
• Sending filters in request body for GET