W3D1: Web servers 101
HTTP Review
- HTTP runs on top of TCP
- HTTPS is conceptually the same, except that the content is encrypted by TLS
- It's transparent at the HTTP level
- Anatomy of an HTTP Request:
GET /maps HTTP/1.1
User-Agent: Chrome 67
Cookie: abcde
- Anatomy of an HTTP Response:
HTTP/1.1 200 OK
X-Powered-By: Express
Content-Type: text/html; charset=utf-8
Content-Length: 14
Date: Mon, 20 Jan 2020 17:07:16 GMT
Connection: keep-alive
<html><body><!-- Some HTML content... --></body></html>
Intro to Web Servers (Express-less demo)
- One callback function handles everything
- Rarely used in practice
- See basic.js
Intro to Express
Example route:
app.get('/hello', (req, res) => {
res.send('Hello world!');
});
What is "middleware?"
It's similar to a route, but it can choose to not answer the request and just continue to the next matching route or middleware in the list.
Example:
app.use((req, res, next) => {
if(req.header('user-agent') === 'Me') {
res.send('Please use a browser');
} else {
next();
}
});
Intro to Server-side view templates with EJS
Templates are used to avoid stringing a bunch of HTML strings together when sending a response. Call res.render(template, variables) to use a template. variables in this case would be an object containing all the variables you want to access in your template code.