ASP.NET Core API Design - MSDN Documentation

Designing Effective APIs with ASP.NET Core

This guide provides best practices and patterns for designing robust, scalable, and user-friendly APIs using ASP.NET Core. Effective API design is crucial for enabling seamless integration between different applications and services.

Core Principles of API Design

When designing an API, consider the following fundamental principles:

Clarity and Consistency: APIs should be intuitive and predictable. Use consistent naming conventions and patterns.
Resource-Oriented Design: Model your API around resources (e.g., users, products, orders) and expose them through URIs.
HTTP Methods: Leverage standard HTTP methods (GET, POST, PUT, DELETE, PATCH) appropriately to represent actions on resources.
Status Codes: Use standard HTTP status codes to communicate the outcome of requests (e.g., 200 OK, 201 Created, 400 Bad Request, 404 Not Found, 500 Internal Server Error).
Data Formats: Support common data formats like JSON and XML for request and response bodies. JSON is generally preferred for its efficiency.
Versioning: Plan for API evolution by implementing a versioning strategy to avoid breaking changes for existing clients.

RESTful API Design with ASP.NET Core

ASP.NET Core Web API is a powerful framework for building RESTful services. Here are key considerations:

Resource Naming and URIs

Use nouns for resource names and pluralize them. Avoid verbs in URIs.

Good: /api/products, /api/customers/123
Bad: /api/getProducts, /api/deleteCustomer

HTTP Methods and Actions

Map HTTP methods to CRUD operations:

HTTP Method	Action	Common Use Case
GET	Retrieve	Fetch a collection of resources or a single resource.
POST	Create	Create a new resource.
PUT	Update/Replace	Update an existing resource entirely.
PATCH	Update/Modify	Partially update an existing resource.
DELETE	Delete	Remove a resource.

Request and Response Bodies

Use JSON for sending and receiving data. ASP.NET Core handles serialization/deserialization automatically.

// Example of a POST request body
{
  "name": "New Gadget",
  "price": 99.99,
  "inStock": true
}

Error Handling

Provide meaningful error responses. Use IActionResult and its derived types for control over the response.

[HttpPost]
public IActionResult CreateProduct([FromBody] Product product)
{
    if (!ModelState.IsValid)
    {
        return BadRequest(ModelState);
    }
    // ... save product ...
    return CreatedAtAction(nameof(GetProduct), new { id = product.Id }, product);
}

Advanced API Design Topics

Authentication and Authorization: Secure your API using JWT, OAuth 2.0, or ASP.NET Core Identity.
Rate Limiting: Protect your API from abuse by implementing rate limiting.
Caching: Improve performance by caching responses.
HATEOAS (Hypermedia as the Engine of Application State): Include links in responses to guide clients to related resources and actions.

"The best API is one that requires no documentation." - Robert C. Martin (Uncle Bob)