How the Web Works
relies on a number of system, protocols and technologies working together in unison
protocol: a set of rules that partners use when they communicate
TCP / IP - layered architecture
applications layer
transport layer
internet layer
link layer
physical transmission of data
establishing logical links
MAC addresses
routes packets between partners
uses IP addresses
IPv4 and IPv6
ensures transmissions arrive in order and without error
broken into packets according to TCP
0.5 - 1k
header
ACK - acknowledges its successful arrival
process-to-process communication
HTTP
SSH
FTP
POP / IMAP / SMTP
DNS
DNS
hosts file
name levels
registration
address resolution
URL
protocol
TCP/IP stack
domain
ftp://example.com/abc.txt
http://example.com/abc.txt
port
identifies the server
path
a software connection point
folder on the server
query string
HTTP
TCP connection on port 80
headers
request headers
host
user agent
accept
accept-encoding
connection
cache-control
response headers
server
last-modified
content-length
content-type
content-encoding
request methods
GET
POST
PUT
DELETE
TRACE
OPTIONS
response codes
200: OK
300: Moved Permanently
304: Not Modified
307: Temporary redirect
400: Bad request
404: Not Found
401: Unauthorized
414: Request URI too long
500: Internal server error
browser
many HTTP requests and responses
rendering
caching
Web Servers
a computer that responds to HTTP requests
application stack
os, web server software, database, scripting language
LAMP, WISA, MEAN
apache / IIS
MySQL, DB2, Oracle
PHP, Python, ASP.NET