RESTful API Design Principles and HTTP Methods
💡 Concept Name
RESTful API Design and HTTP Methods provide the foundation for building APIs that are scalable, maintainable, and predictable, enabling seamless communication between clients and servers.
📘 Quick Intro
REST, or Representational State Transfer, is a popular architectural style for APIs. HTTP methods such as GET, POST, PUT, and DELETE specify how resources are accessed and manipulated in a standardized way.
🧠 Analogy / Short Story
Think of a RESTful API like a restaurant menu: the URL represents the dish, and the HTTP method is the action—GET orders a dish, POST adds a new dish, PUT modifies your order, and DELETE removes it.
🔧 Technical Explanation
- 🌐 Statelessness: Each request is independent and contains all necessary information; the server does not store client context.
- 🔗 Uniform Interface: Resources are accessed via standard URIs and HTTP methods.
- 🧠 Client-Server Separation: Clear separation between frontend and backend responsibilities.
- 📄 Resource Representation: Data is typically formatted as JSON or XML for communication.
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📤 HTTP Methods Explained:
- GET – Retrieve resource(s), e.g.,
/users - POST – Create a new resource
- PUT – Replace an existing resource
- PATCH – Apply partial updates to a resource
- DELETE – Remove a resource
- OPTIONS / HEAD – Retrieve meta information
- GET – Retrieve resource(s), e.g.,
🎯 Purpose & Use Case
- ✅ Create clear, consistent interfaces for interacting with resources.
- ✅ Support scalability and reusability in distributed systems.
- ✅ Commonly used in web applications, microservices, and mobile backends.
💻 Real Code Example
// Using HttpClient in C# to consume a REST API
HttpClient client = new HttpClient();
var response = await client.GetAsync("https://api.example.com/users/1");
string content = await response.Content.ReadAsStringAsync();
Console.WriteLine(content);
❓ Interview Q&A
Q1: What is REST?
A: REST is an architectural style that uses stateless communication, resource-based URLs, and standard HTTP methods.
Q2: How does REST differ from SOAP?
A: REST uses simple HTTP and lightweight formats like JSON, while SOAP relies on XML and strict protocols.
Q3: Which HTTP methods are idempotent?
A: GET, PUT, DELETE, and HEAD are idempotent, meaning multiple identical calls have the same effect.
Q4: When do you use PATCH instead of PUT?
A: PATCH is for partial updates, while PUT replaces the entire resource.
Q5: What is the role of the OPTIONS method?
A: It provides information about allowed communication options, often used in CORS preflight requests.
📝 MCQs
Q1. Which HTTP method is used to retrieve data?
- GET
- POST
- PUT
- DELETE
Q2. Which HTTP method removes a resource?
- PATCH
- GET
- DELETE
- HEAD
Q3. Which method partially updates a resource?
- POST
- PATCH
- PUT
- OPTIONS
Q4. Which method requests only headers?
- GET
- HEAD
- OPTIONS
- POST
Q5. What defines a RESTful API?
- Uses SOAP
- Encrypted only
- Stateless and resource-based communication
- Only GET method
Q6. Which HTTP method is safe and idempotent?
- PUT
- PATCH
- GET
- POST
Q7. What does PUT do?
- Deletes it
- Reads it
- Replaces a resource
- Compresses it
Q8. Which method is used in CORS preflight?
- GET
- OPTIONS
- PATCH
- DELETE
Q9. What data format is common in REST APIs?
- XML
- HTML
- JSON
- CSV
Q10. Why are stateless APIs preferred?
- Encryption
- Scalability
- Speed
- Complexity
💡 Bonus Insight
RESTful APIs are easier to scale, cache, and maintain. Using correct HTTP methods ensures developers have predictable and readable interfaces.
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