GitHub/quartz
1
0
Fork 2
mirror of https://github.com/jackyzha0/quartz.git synced 2025-12-27 14:54:05 -06:00
Code Issues Actions Packages Projects Releases Wiki Activity
bfc45a0257
quartz/content/notes/17-app-layer.md
Jet Hughes bfc45a0257 vault backup: 2022-10-17 11:58:03
2022-10-17 11:58:03 +13:00

2.1 KiB
Raw Blame History

title aliases tags
17-app-layer
cosc203
lecture

Client-server vs peer to peer

  • social network
  • email
  • multi player games
  • video streaming
  • P2P file sharing
  • voice over IP e.g., skype
  • remote ogin

Principles

  • run of different end systems
  • communicate over network
  • no need to run application specific software on netwrk-core devices

client-server

sercer

  • provide services to clients
  • always on
  • often in data centers, for scaling
  • needs to powerful
    • multiple client requesting info at the same time
    • have specialzed software

client

  • request services by contacting and communicating with server
  • may be intermittently connected
  • do not communicate directly with each other

peer 2 peer

  • no alwasy on server
  • decentralize resource on a network
  • end systems are both client and servers
  • end systems communcatae directly
  • take advantage of distrivuted shared resources (bandwidth, CPU storage)
  • operate in dynamic environment with frequent join and leave
  • e.g., bitTorrent, blockchain

communication

  • process: network application running with a host
    • client proces and server process
    • processes in different hosts communicate by exhanging messages
  • process must have identifiers
    • ip address to differentiate processes in different hosts
      • IPv4: 10.96.35.21 • IPv6: fe80::44b:184c:7ebb:6524
    • port number to differentiate processes in same host
      • HTTP server (80), mail server (25)

functions of application protocols

protocols define:

  • types of messages
    • e.e.g, request, response
  • message syntax
    • what fields in messages and how field are delineated
  • semantics
    • meaning on information in fields
  • communcation rules
    • when and how proceses send and response to messages

WEB http

  • client server model
    • browser requests, recieves and displays web objects
    • server sends objects in response to requests
  • HTTP
    • communcation betwen browsers and servers
  • https
    • extensioin of http that uses transport layer security for security

methods

  • get, head, post, put (request to store a webpage), delete, link (connect two existing resources), unlink

exampl

Email

DNS

Socket programming