The document discusses server architecture and different types of servers. It describes common server roles like web servers, application servers, and proxy servers. It provides examples of simple web servers written in Node.js and Ruby. Popular web servers mentioned include Nginx and Apache. Different hosting options for servers are also covered, such as virtual dedicated servers (VDS), virtual private servers (VPS), and cloud servers hosted on platforms like Amazon AWS, Google Cloud, and Microsoft Azure.

1. Server Architecture
MA2018
Bogdan Sergiienko

2. What is server?
Hardware or software that provides functionality for other
programs/devices like:
● Web server
● Application Server
● Mail server
● File server
● Proxy server
● etc

3. Server roles and design
For web application development context main servers roles
are:
● Web server - serve static HTML and resources
● Application server - serves logical part of a web
application
● Proxy/gateway/load balancing server - simplifies access
to the application servers and balance load between
nodes

4. The most simple web server in
Node.js
const http = require('http')
const port = 3000
const requestHandler = (request, response) => {
console.log(request.url)
response.end('Hello Node.js Server!')
}
const server = http.createServer(requestHandler)
server.listen(port, (err) => {
if (err) {
return console.log('something bad happened', err)
}
console.log(`server is listening on ${port}`)
})

5. The most simple web server in
Ruby
require 'socket'
server = TCPServer.new 5678
while session = server.accept
request = session.gets
puts request
session.print "HTTP/1.1 200rn" # 1
session.print "Content-Type: text/htmlrn" # 2
session.print "rn" # 3
session.print "Hello world! The time is #{Time.now}" #4
session.close
end

6. The most simple HTTP client
k8test@k8test:~$ telnet google.com 80
Trying 216.58.215.110...
Connected to google.com.
Escape character is '^]'.
GET /
HTTP/1.0 200 OK

7. Server response headers
Date: Wed, 24 Oct 2018 10:25:44 GMT
Expires: -1
Cache-Control: private, max-age=0
Content-Type: text/html; charset=ISO-8859-1
P3P: CP="This is not a P3P policy! See g.co/p3phelp for more info."
Server: gws
X-XSS-Protection: 1; mode=block
X-Frame-Options: SAMEORIGIN
Set-Cookie: 1P_JAR=2018-10-24-10; expires=Fri, 23-Nov-2018 10:25:44 GMT; path=/;
domain=.google.com
Set-Cookie: 123456; expires=Thu, 25-Apr-2019 10:25:44 GMT; path=/; domain=.google.com;
HttpOnly
Accept-Ranges: none
Vary: Accept-Encoding

8. Web server + Application server
Web server Application server
GET /
Browser
GET /style.css
GET /logo.png

9. Web server/Load balancer
Web server
+
Load balancer
Application server
GET /
Browser
GET /style.css
GET /logo.png
Application server
Application server

10. Popular web servers

11. VDS/VDS/Cloud Server
comparison
Type Pros: Cons:
VDS ● Best performance
● Full control over hardware
● Full responsibility for
backups, health check,
etc
● Long setup process
VPS ● Moderate initialization
time
● Some additional services
like backup and services
are available
● Hardware resources are
shared
Cloud server ● Cloud infrastructure saves
efforts
● Zero control over
hardware and server
location is fluid

12. Cloud platforms
● Digital Ocean ● Amazon AWS
● Google Cloud Platform
● Microsoft Azure