T17: API Endpoints

An API (Application Programming Interface) is a set of endpoints your server exposes for clients to interact with data. REST is a design convention where URLs represent resources and HTTP methods represent actions. Think of it as a menu at a restaurant - the menu lists what you can order and how.

REST Conventions

RESTful APIs follow a pattern: resources are nouns in the URL, actions are HTTP methods.

// GET    /api/users      - List all users
// GET    /api/users/1    - Get user with id 1
// POST   /api/users      - Create a new user
// PUT    /api/users/1    - Update user 1
// DELETE /api/users/1    - Delete user 1

Building Endpoints

const server = http.createServer((req, res) => {
    const url = req.url;
    const method = req.method;

    res.setHeader("Content-Type", "application/json");

    if (url === "/api/users" && method === "GET") {
        res.end(JSON.stringify(users));
    } else if (url === "/api/users" && method === "POST") {
        let body = "";
        req.on("data", chunk => body += chunk);
        req.on("end", () => {
            const user = JSON.parse(body);
            users.push(user);
            res.writeHead(201);
            res.end(JSON.stringify(user));
        });
    } else {
        res.writeHead(404);
        res.end(JSON.stringify({ error: "Not Found" }));
    }
});

flowchart TD A[Client Request] --> B{Route Match} B -->|GET /api/users| C[Return user list] B -->|POST /api/users| D[Create new user] B -->|GET /api/users/:id| E[Return single user] B -->|PUT /api/users/:id| F[Update user] B -->|DELETE /api/users/:id| G[Remove user] B -->|No match| H[404 Not Found]

Key Takeaways

REST uses URLs as resource identifiers and HTTP methods as actions
GET reads, POST creates, PUT updates, DELETE removes
API responses should be JSON with appropriate status codes
Always handle unknown routes with a 404 response