Introduction to REST

Terminology

Request Endpoint (URL path): The part of a URL, minus the domain. The "location" or path of a resource on the server. This is an actual location in the case of static files but is a virtual location when requesting JSON data.
HTTP Method: An action that represents what the client would like the server to do with a resource. In this course, we will cover GET (Read), POST (Create), PUT (Update) and DELETE (Delete, duh).
Route: The combination of both a Request Path and an HTTP Method tells the server how to route a request to the proper location in our code.

RESTful APIs define how a client requests information from a server over HTTP. It is based largely on HTTP Methods and URL path of a request. Much of our code in Express will be organized using these two pieces of information.

CRUD operations

CRUD represents the four ways we can use or affect information which map directly to HTTP Methods:

Create a resource: POST Request
Read a resource: GET Request
Update a resource: PUT Request
Delete a resource: DELETE Request

Routes: a key concept

The Request URL and HTTP Method are very important to Express. They are used to route a request to the proper section of our application. In the case of REST APIs, we document our routes like so:

GET /users
GET /users/:id
POST /users
PUT /users/:id
DELETE /users/:id

In Express, routes are represented as event listeners similar to click or submit handlers in a browser:

// Send a resource back to the browser
app.get([url path], [function])

// Create a resource in the database
app.post([url path], [function])

// Update a resource in the database
app.put([url path], [function])

// Delete a resource from the database
app.delete([url path], [function])

Much of the code we write for the rest of the course will be organized in the functions attached to routes.

Key Takeaways

Think of server.js as a configuration file for our HTTP server. It runs once when the server starts and leaves behind event listeners for particular path/method combinations.
Unlike our simple Node and browser examples, most of our code will be inside methods (functions attached to objects).
Most Express methods will be asynchronous: our code will only run when a request with a particular path and method are received.
For every request, Express will create request and response objects that are passed from method to method until the response is sent.