REST API – 20 Basic Consepts

1. Stateless

Explanation: In REST, each API call is independent and contains all the information needed for its execution.

C# Example:

HttpClient client = new HttpClient();
var response = await client.GetAsync("https://api.example.com/users/1");

2. Client-Server Architecture

Explanation: REST APIs operate on a client-server model, separating the client logic from the server logic.

C# Example:
Creating a Web API server and consuming it using HttpClient.

3. Uniform Interface

Explanation: RESTful APIs follow a uniform interface, making it easier to understand and interact with them.

C# Example:
GET, POST, PUT, DELETE HTTP methods.

4. Resource-Based

Explanation: In REST, everything is considered a resource and is accessed via its resource URL.

C# Example:

[HttpGet("api/users/{id}")]
public ActionResult GetUser(int id) { /* ... */ }

5. Layered System

Explanation: REST allows you to have multiple layers (e.g., load balancing, security) between client and server.

C# Example:
Using middleware in ASP.NET Core for caching, authentication, etc.

6. Cacheability

Explanation: RESTful APIs explicitly indicate whether the client can cache the resource.

C# Example:
Using HTTP headers like Cache-Control.

7. Media Types

Explanation: RESTful APIs can return different media types like JSON, XML, etc.

C# Example:

[Produces("application/json")]
public class UsersController : Controller { /* ... */ }

8. Versioning

Explanation: APIs often have multiple versions to support backward compatibility.

C# Example:
Using URL paths like /v1/users and /v2/users.

9. Error Handling

Explanation: REST APIs return standardized HTTP status codes to indicate errors.

C# Example:

return NotFound("User not found");

10. Pagination

Explanation: Paginating large sets of resources is a common practice in RESTful APIs.

C# Example:
Adding query parameters like ?page=1&limit=10.

11. Filtering and Sorting

Explanation: REST APIs often allow clients to filter and sort data using query parameters.

C# Example:

public ActionResult GetUsers([FromQuery] string sort) { /* ... */ }

12. HATEOAS

Explanation: Hypermedia as the engine of application state; navigating APIs through hypermedia links.

C# Example:
Returning URLs for related resources in API responses.

13. Idempotence

Explanation: Certain operations (GET, PUT, DELETE) produce the same result, even if repeated multiple times.

C# Example:
A DELETE request that deletes a resource once and then has no effect.

14. Rate Limiting

Explanation: Limiting the number of requests a client can make in a given time period.

C# Example:
Using middleware to enforce rate limits.

15. Authentication & Authorization

Explanation: Ensuring that only authorized clients can access resources.

C# Example:
JWT, OAuth2.

16. Logging and Monitoring

Explanation: Tracking API usage and errors for debugging and analytics.

C# Example:
Using logging frameworks like Serilog.

17. ETags

Explanation: ETags are used for conditional requests, reducing unnecessary data transfer.

C# Example:
Using If-None-Match header.

18. Asynchronous Processing

Explanation: Some tasks can be processed asynchronously and their state can be polled later.

C# Example:
Returning a 202 Accepted status and a URL to check the processing status.

19. Request and Response Headers

Explanation: Headers are used to convey metadata for both request and response.

C# Example:
Custom headers for tracking or authentication.

20. URI Design

Explanation: The design of URIs should be intuitive and convey the resource hierarchy.

C# Example:
/users/1/orders/2

Pros and Cons of REST Architecture

Pros

• Simplicity: REST is straightforward to understand and implement.
• Scalability: Stateless servers enable excellent scalability.
• Flexibility: It supports multiple types of data formats.

Cons

• Overhead: Stateless interactions can involve more data transfer.
• Limited Functionality: REST is less suitable for operations that can’t be easily mapped to HTTP verbs.
• Learning Curve: While REST is simple, it requires a deep understanding to use effectively.

I hope you find this deep dive into RESTful API architecture useful!